TOMOYO Linux Cross Reference
Linux/kernel/bpf/verifier.c

   // SPDX-License-Identifier: GPL-2.0-only
   /* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
    * Copyright (c) 2016 Facebook
    * Copyright (c) 2018 Covalent IO, Inc. http://covalent.io
    */
   #include <uapi/linux/btf.h>
   #include <linux/bpf-cgroup.h>
   #include <linux/kernel.h>
   #include <linux/types.h>
  #include <linux/slab.h>
  #include <linux/bpf.h>
  #include <linux/btf.h>
  #include <linux/bpf_verifier.h>
  #include <linux/filter.h>
  #include <net/netlink.h>
  #include <linux/file.h>
  #include <linux/vmalloc.h>
  #include <linux/stringify.h>
  #include <linux/bsearch.h>
  #include <linux/sort.h>
  #include <linux/perf_event.h>
  #include <linux/ctype.h>
  #include <linux/error-injection.h>
  #include <linux/bpf_lsm.h>
  #include <linux/btf_ids.h>
  #include <linux/poison.h>
  #include <linux/module.h>
  #include <linux/cpumask.h>
  #include <linux/bpf_mem_alloc.h>
  #include <net/xdp.h>
  
  #include "disasm.h"
  
  static const struct bpf_verifier_ops * const bpf_verifier_ops[] = {
  #define BPF_PROG_TYPE(_id, _name, prog_ctx_type, kern_ctx_type) \
          [_id] = & _name ## _verifier_ops,
  #define BPF_MAP_TYPE(_id, _ops)
  #define BPF_LINK_TYPE(_id, _name)
  #include <linux/bpf_types.h>
  #undef BPF_PROG_TYPE
  #undef BPF_MAP_TYPE
  #undef BPF_LINK_TYPE
  };
  
  struct bpf_mem_alloc bpf_global_percpu_ma;
  static bool bpf_global_percpu_ma_set;
  
  /* bpf_check() is a static code analyzer that walks eBPF program
   * instruction by instruction and updates register/stack state.
   * All paths of conditional branches are analyzed until 'bpf_exit' insn.
   *
   * The first pass is depth-first-search to check that the program is a DAG.
   * It rejects the following programs:
   * - larger than BPF_MAXINSNS insns
   * - if loop is present (detected via back-edge)
   * - unreachable insns exist (shouldn't be a forest. program = one function)
   * - out of bounds or malformed jumps
   * The second pass is all possible path descent from the 1st insn.
   * Since it's analyzing all paths through the program, the length of the
   * analysis is limited to 64k insn, which may be hit even if total number of
   * insn is less then 4K, but there are too many branches that change stack/regs.
   * Number of 'branches to be analyzed' is limited to 1k
   *
   * On entry to each instruction, each register has a type, and the instruction
   * changes the types of the registers depending on instruction semantics.
   * If instruction is BPF_MOV64_REG(BPF_REG_1, BPF_REG_5), then type of R5 is
   * copied to R1.
   *
   * All registers are 64-bit.
   * R0 - return register
   * R1-R5 argument passing registers
   * R6-R9 callee saved registers
   * R10 - frame pointer read-only
   *
   * At the start of BPF program the register R1 contains a pointer to bpf_context
   * and has type PTR_TO_CTX.
   *
   * Verifier tracks arithmetic operations on pointers in case:
   *    BPF_MOV64_REG(BPF_REG_1, BPF_REG_10),
   *    BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, -20),
   * 1st insn copies R10 (which has FRAME_PTR) type into R1
   * and 2nd arithmetic instruction is pattern matched to recognize
   * that it wants to construct a pointer to some element within stack.
   * So after 2nd insn, the register R1 has type PTR_TO_STACK
   * (and -20 constant is saved for further stack bounds checking).
   * Meaning that this reg is a pointer to stack plus known immediate constant.
   *
   * Most of the time the registers have SCALAR_VALUE type, which
   * means the register has some value, but it's not a valid pointer.
   * (like pointer plus pointer becomes SCALAR_VALUE type)
   *
   * When verifier sees load or store instructions the type of base register
   * can be: PTR_TO_MAP_VALUE, PTR_TO_CTX, PTR_TO_STACK, PTR_TO_SOCKET. These are
   * four pointer types recognized by check_mem_access() function.
   *
   * PTR_TO_MAP_VALUE means that this register is pointing to 'map element value'
   * and the range of [ptr, ptr + map's value_size) is accessible.
   *
   * registers used to pass values to function calls are checked against
  * function argument constraints.
  *
  * ARG_PTR_TO_MAP_KEY is one of such argument constraints.
  * It means that the register type passed to this function must be
  * PTR_TO_STACK and it will be used inside the function as
  * 'pointer to map element key'
  *
  * For example the argument constraints for bpf_map_lookup_elem():
  *   .ret_type = RET_PTR_TO_MAP_VALUE_OR_NULL,
  *   .arg1_type = ARG_CONST_MAP_PTR,
  *   .arg2_type = ARG_PTR_TO_MAP_KEY,
  *
  * ret_type says that this function returns 'pointer to map elem value or null'
  * function expects 1st argument to be a const pointer to 'struct bpf_map' and
  * 2nd argument should be a pointer to stack, which will be used inside
  * the helper function as a pointer to map element key.
  *
  * On the kernel side the helper function looks like:
  * u64 bpf_map_lookup_elem(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
  * {
  *    struct bpf_map *map = (struct bpf_map *) (unsigned long) r1;
  *    void *key = (void *) (unsigned long) r2;
  *    void *value;
  *
  *    here kernel can access 'key' and 'map' pointers safely, knowing that
  *    [key, key + map->key_size) bytes are valid and were initialized on
  *    the stack of eBPF program.
  * }
  *
  * Corresponding eBPF program may look like:
  *    BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),  // after this insn R2 type is FRAME_PTR
  *    BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -4), // after this insn R2 type is PTR_TO_STACK
  *    BPF_LD_MAP_FD(BPF_REG_1, map_fd),      // after this insn R1 type is CONST_PTR_TO_MAP
  *    BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem),
  * here verifier looks at prototype of map_lookup_elem() and sees:
  * .arg1_type == ARG_CONST_MAP_PTR and R1->type == CONST_PTR_TO_MAP, which is ok,
  * Now verifier knows that this map has key of R1->map_ptr->key_size bytes
  *
  * Then .arg2_type == ARG_PTR_TO_MAP_KEY and R2->type == PTR_TO_STACK, ok so far,
  * Now verifier checks that [R2, R2 + map's key_size) are within stack limits
  * and were initialized prior to this call.
  * If it's ok, then verifier allows this BPF_CALL insn and looks at
  * .ret_type which is RET_PTR_TO_MAP_VALUE_OR_NULL, so it sets
  * R0->type = PTR_TO_MAP_VALUE_OR_NULL which means bpf_map_lookup_elem() function
  * returns either pointer to map value or NULL.
  *
  * When type PTR_TO_MAP_VALUE_OR_NULL passes through 'if (reg != 0) goto +off'
  * insn, the register holding that pointer in the true branch changes state to
  * PTR_TO_MAP_VALUE and the same register changes state to CONST_IMM in the false
  * branch. See check_cond_jmp_op().
  *
  * After the call R0 is set to return type of the function and registers R1-R5
  * are set to NOT_INIT to indicate that they are no longer readable.
  *
  * The following reference types represent a potential reference to a kernel
  * resource which, after first being allocated, must be checked and freed by
  * the BPF program:
  * - PTR_TO_SOCKET_OR_NULL, PTR_TO_SOCKET
  *
  * When the verifier sees a helper call return a reference type, it allocates a
  * pointer id for the reference and stores it in the current function state.
  * Similar to the way that PTR_TO_MAP_VALUE_OR_NULL is converted into
  * PTR_TO_MAP_VALUE, PTR_TO_SOCKET_OR_NULL becomes PTR_TO_SOCKET when the type
  * passes through a NULL-check conditional. For the branch wherein the state is
  * changed to CONST_IMM, the verifier releases the reference.
  *
  * For each helper function that allocates a reference, such as
  * bpf_sk_lookup_tcp(), there is a corresponding release function, such as
  * bpf_sk_release(). When a reference type passes into the release function,
  * the verifier also releases the reference. If any unchecked or unreleased
  * reference remains at the end of the program, the verifier rejects it.
  */
 
 /* verifier_state + insn_idx are pushed to stack when branch is encountered */
 struct bpf_verifier_stack_elem {
         /* verifier state is 'st'
          * before processing instruction 'insn_idx'
          * and after processing instruction 'prev_insn_idx'
          */
         struct bpf_verifier_state st;
         int insn_idx;
         int prev_insn_idx;
         struct bpf_verifier_stack_elem *next;
         /* length of verifier log at the time this state was pushed on stack */
         u32 log_pos;
 };
 
 #define BPF_COMPLEXITY_LIMIT_JMP_SEQ    8192
 #define BPF_COMPLEXITY_LIMIT_STATES     64
 
 #define BPF_MAP_KEY_POISON      (1ULL << 63)
 #define BPF_MAP_KEY_SEEN        (1ULL << 62)
 
 #define BPF_GLOBAL_PERCPU_MA_MAX_SIZE  512
 
 static int acquire_reference_state(struct bpf_verifier_env *env, int insn_idx);
 static int release_reference(struct bpf_verifier_env *env, int ref_obj_id);
 static void invalidate_non_owning_refs(struct bpf_verifier_env *env);
 static bool in_rbtree_lock_required_cb(struct bpf_verifier_env *env);
 static int ref_set_non_owning(struct bpf_verifier_env *env,
                               struct bpf_reg_state *reg);
 static void specialize_kfunc(struct bpf_verifier_env *env,
                              u32 func_id, u16 offset, unsigned long *addr);
 static bool is_trusted_reg(const struct bpf_reg_state *reg);
 
 static bool bpf_map_ptr_poisoned(const struct bpf_insn_aux_data *aux)
 {
         return aux->map_ptr_state.poison;
 }
 
 static bool bpf_map_ptr_unpriv(const struct bpf_insn_aux_data *aux)
 {
         return aux->map_ptr_state.unpriv;
 }
 
 static void bpf_map_ptr_store(struct bpf_insn_aux_data *aux,
                               struct bpf_map *map,
                               bool unpriv, bool poison)
 {
         unpriv |= bpf_map_ptr_unpriv(aux);
         aux->map_ptr_state.unpriv = unpriv;
         aux->map_ptr_state.poison = poison;
         aux->map_ptr_state.map_ptr = map;
 }
 
 static bool bpf_map_key_poisoned(const struct bpf_insn_aux_data *aux)
 {
         return aux->map_key_state & BPF_MAP_KEY_POISON;
 }
 
 static bool bpf_map_key_unseen(const struct bpf_insn_aux_data *aux)
 {
         return !(aux->map_key_state & BPF_MAP_KEY_SEEN);
 }
 
 static u64 bpf_map_key_immediate(const struct bpf_insn_aux_data *aux)
 {
         return aux->map_key_state & ~(BPF_MAP_KEY_SEEN | BPF_MAP_KEY_POISON);
 }
 
 static void bpf_map_key_store(struct bpf_insn_aux_data *aux, u64 state)
 {
         bool poisoned = bpf_map_key_poisoned(aux);
 
         aux->map_key_state = state | BPF_MAP_KEY_SEEN |
                              (poisoned ? BPF_MAP_KEY_POISON : 0ULL);
 }
 
 static bool bpf_helper_call(const struct bpf_insn *insn)
 {
         return insn->code == (BPF_JMP | BPF_CALL) &&
                insn->src_reg == 0;
 }
 
 static bool bpf_pseudo_call(const struct bpf_insn *insn)
 {
         return insn->code == (BPF_JMP | BPF_CALL) &&
                insn->src_reg == BPF_PSEUDO_CALL;
 }
 
 static bool bpf_pseudo_kfunc_call(const struct bpf_insn *insn)
 {
         return insn->code == (BPF_JMP | BPF_CALL) &&
                insn->src_reg == BPF_PSEUDO_KFUNC_CALL;
 }
 
 struct bpf_call_arg_meta {
         struct bpf_map *map_ptr;
         bool raw_mode;
         bool pkt_access;
         u8 release_regno;
         int regno;
         int access_size;
         int mem_size;
         u64 msize_max_value;
         int ref_obj_id;
         int dynptr_id;
         int map_uid;
         int func_id;
         struct btf *btf;
         u32 btf_id;
         struct btf *ret_btf;
         u32 ret_btf_id;
         u32 subprogno;
         struct btf_field *kptr_field;
 };
 
 struct bpf_kfunc_call_arg_meta {
         /* In parameters */
         struct btf *btf;
         u32 func_id;
         u32 kfunc_flags;
         const struct btf_type *func_proto;
         const char *func_name;
         /* Out parameters */
         u32 ref_obj_id;
         u8 release_regno;
         bool r0_rdonly;
         u32 ret_btf_id;
         u64 r0_size;
         u32 subprogno;
         struct {
                 u64 value;
                 bool found;
         } arg_constant;
 
         /* arg_{btf,btf_id,owning_ref} are used by kfunc-specific handling,
          * generally to pass info about user-defined local kptr types to later
          * verification logic
          *   bpf_obj_drop/bpf_percpu_obj_drop
          *     Record the local kptr type to be drop'd
          *   bpf_refcount_acquire (via KF_ARG_PTR_TO_REFCOUNTED_KPTR arg type)
          *     Record the local kptr type to be refcount_incr'd and use
          *     arg_owning_ref to determine whether refcount_acquire should be
          *     fallible
          */
         struct btf *arg_btf;
         u32 arg_btf_id;
         bool arg_owning_ref;
 
         struct {
                 struct btf_field *field;
         } arg_list_head;
         struct {
                 struct btf_field *field;
         } arg_rbtree_root;
         struct {
                 enum bpf_dynptr_type type;
                 u32 id;
                 u32 ref_obj_id;
         } initialized_dynptr;
         struct {
                 u8 spi;
                 u8 frameno;
         } iter;
         struct {
                 struct bpf_map *ptr;
                 int uid;
         } map;
         u64 mem_size;
 };
 
 struct btf *btf_vmlinux;
 
 static const char *btf_type_name(const struct btf *btf, u32 id)
 {
         return btf_name_by_offset(btf, btf_type_by_id(btf, id)->name_off);
 }
 
 static DEFINE_MUTEX(bpf_verifier_lock);
 static DEFINE_MUTEX(bpf_percpu_ma_lock);
 
 __printf(2, 3) static void verbose(void *private_data, const char *fmt, ...)
 {
         struct bpf_verifier_env *env = private_data;
         va_list args;
 
         if (!bpf_verifier_log_needed(&env->log))
                 return;
 
         va_start(args, fmt);
         bpf_verifier_vlog(&env->log, fmt, args);
         va_end(args);
 }
 
 static void verbose_invalid_scalar(struct bpf_verifier_env *env,
                                    struct bpf_reg_state *reg,
                                    struct bpf_retval_range range, const char *ctx,
                                    const char *reg_name)
 {
         bool unknown = true;
 
         verbose(env, "%s the register %s has", ctx, reg_name);
         if (reg->smin_value > S64_MIN) {
                 verbose(env, " smin=%lld", reg->smin_value);
                 unknown = false;
         }
         if (reg->smax_value < S64_MAX) {
                 verbose(env, " smax=%lld", reg->smax_value);
                 unknown = false;
         }
         if (unknown)
                 verbose(env, " unknown scalar value");
         verbose(env, " should have been in [%d, %d]\n", range.minval, range.maxval);
 }
 
 static bool type_may_be_null(u32 type)
 {
         return type & PTR_MAYBE_NULL;
 }
 
 static bool reg_not_null(const struct bpf_reg_state *reg)
 {
         enum bpf_reg_type type;
 
         type = reg->type;
         if (type_may_be_null(type))
                 return false;
 
         type = base_type(type);
         return type == PTR_TO_SOCKET ||
                 type == PTR_TO_TCP_SOCK ||
                 type == PTR_TO_MAP_VALUE ||
                 type == PTR_TO_MAP_KEY ||
                 type == PTR_TO_SOCK_COMMON ||
                 (type == PTR_TO_BTF_ID && is_trusted_reg(reg)) ||
                 type == PTR_TO_MEM;
 }
 
 static struct btf_record *reg_btf_record(const struct bpf_reg_state *reg)
 {
         struct btf_record *rec = NULL;
         struct btf_struct_meta *meta;
 
         if (reg->type == PTR_TO_MAP_VALUE) {
                 rec = reg->map_ptr->record;
         } else if (type_is_ptr_alloc_obj(reg->type)) {
                 meta = btf_find_struct_meta(reg->btf, reg->btf_id);
                 if (meta)
                         rec = meta->record;
         }
         return rec;
 }
 
 static bool subprog_is_global(const struct bpf_verifier_env *env, int subprog)
 {
         struct bpf_func_info_aux *aux = env->prog->aux->func_info_aux;
 
         return aux && aux[subprog].linkage == BTF_FUNC_GLOBAL;
 }
 
 static const char *subprog_name(const struct bpf_verifier_env *env, int subprog)
 {
         struct bpf_func_info *info;
 
         if (!env->prog->aux->func_info)
                 return "";
 
         info = &env->prog->aux->func_info[subprog];
         return btf_type_name(env->prog->aux->btf, info->type_id);
 }
 
 static void mark_subprog_exc_cb(struct bpf_verifier_env *env, int subprog)
 {
         struct bpf_subprog_info *info = subprog_info(env, subprog);
 
         info->is_cb = true;
         info->is_async_cb = true;
         info->is_exception_cb = true;
 }
 
 static bool subprog_is_exc_cb(struct bpf_verifier_env *env, int subprog)
 {
         return subprog_info(env, subprog)->is_exception_cb;
 }
 
 static bool reg_may_point_to_spin_lock(const struct bpf_reg_state *reg)
 {
         return btf_record_has_field(reg_btf_record(reg), BPF_SPIN_LOCK);
 }
 
 static bool type_is_rdonly_mem(u32 type)
 {
         return type & MEM_RDONLY;
 }
 
 static bool is_acquire_function(enum bpf_func_id func_id,
                                 const struct bpf_map *map)
 {
         enum bpf_map_type map_type = map ? map->map_type : BPF_MAP_TYPE_UNSPEC;
 
         if (func_id == BPF_FUNC_sk_lookup_tcp ||
             func_id == BPF_FUNC_sk_lookup_udp ||
             func_id == BPF_FUNC_skc_lookup_tcp ||
             func_id == BPF_FUNC_ringbuf_reserve ||
             func_id == BPF_FUNC_kptr_xchg)
                 return true;
 
         if (func_id == BPF_FUNC_map_lookup_elem &&
             (map_type == BPF_MAP_TYPE_SOCKMAP ||
              map_type == BPF_MAP_TYPE_SOCKHASH))
                 return true;
 
         return false;
 }
 
 static bool is_ptr_cast_function(enum bpf_func_id func_id)
 {
         return func_id == BPF_FUNC_tcp_sock ||
                 func_id == BPF_FUNC_sk_fullsock ||
                 func_id == BPF_FUNC_skc_to_tcp_sock ||
                 func_id == BPF_FUNC_skc_to_tcp6_sock ||
                 func_id == BPF_FUNC_skc_to_udp6_sock ||
                 func_id == BPF_FUNC_skc_to_mptcp_sock ||
                 func_id == BPF_FUNC_skc_to_tcp_timewait_sock ||
                 func_id == BPF_FUNC_skc_to_tcp_request_sock;
 }
 
 static bool is_dynptr_ref_function(enum bpf_func_id func_id)
 {
         return func_id == BPF_FUNC_dynptr_data;
 }
 
 static bool is_sync_callback_calling_kfunc(u32 btf_id);
 static bool is_async_callback_calling_kfunc(u32 btf_id);
 static bool is_callback_calling_kfunc(u32 btf_id);
 static bool is_bpf_throw_kfunc(struct bpf_insn *insn);
 
 static bool is_bpf_wq_set_callback_impl_kfunc(u32 btf_id);
 
 static bool is_sync_callback_calling_function(enum bpf_func_id func_id)
 {
         return func_id == BPF_FUNC_for_each_map_elem ||
                func_id == BPF_FUNC_find_vma ||
                func_id == BPF_FUNC_loop ||
                func_id == BPF_FUNC_user_ringbuf_drain;
 }
 
 static bool is_async_callback_calling_function(enum bpf_func_id func_id)
 {
         return func_id == BPF_FUNC_timer_set_callback;
 }
 
 static bool is_callback_calling_function(enum bpf_func_id func_id)
 {
         return is_sync_callback_calling_function(func_id) ||
                is_async_callback_calling_function(func_id);
 }
 
 static bool is_sync_callback_calling_insn(struct bpf_insn *insn)
 {
         return (bpf_helper_call(insn) && is_sync_callback_calling_function(insn->imm)) ||
                (bpf_pseudo_kfunc_call(insn) && is_sync_callback_calling_kfunc(insn->imm));
 }
 
 static bool is_async_callback_calling_insn(struct bpf_insn *insn)
 {
         return (bpf_helper_call(insn) && is_async_callback_calling_function(insn->imm)) ||
                (bpf_pseudo_kfunc_call(insn) && is_async_callback_calling_kfunc(insn->imm));
 }
 
 static bool is_may_goto_insn(struct bpf_insn *insn)
 {
         return insn->code == (BPF_JMP | BPF_JCOND) && insn->src_reg == BPF_MAY_GOTO;
 }
 
 static bool is_may_goto_insn_at(struct bpf_verifier_env *env, int insn_idx)
 {
         return is_may_goto_insn(&env->prog->insnsi[insn_idx]);
 }
 
 static bool is_storage_get_function(enum bpf_func_id func_id)
 {
         return func_id == BPF_FUNC_sk_storage_get ||
                func_id == BPF_FUNC_inode_storage_get ||
                func_id == BPF_FUNC_task_storage_get ||
                func_id == BPF_FUNC_cgrp_storage_get;
 }
 
 static bool helper_multiple_ref_obj_use(enum bpf_func_id func_id,
                                         const struct bpf_map *map)
 {
         int ref_obj_uses = 0;
 
         if (is_ptr_cast_function(func_id))
                 ref_obj_uses++;
         if (is_acquire_function(func_id, map))
                 ref_obj_uses++;
         if (is_dynptr_ref_function(func_id))
                 ref_obj_uses++;
 
         return ref_obj_uses > 1;
 }
 
 static bool is_cmpxchg_insn(const struct bpf_insn *insn)
 {
         return BPF_CLASS(insn->code) == BPF_STX &&
                BPF_MODE(insn->code) == BPF_ATOMIC &&
                insn->imm == BPF_CMPXCHG;
 }
 
 static int __get_spi(s32 off)
 {
         return (-off - 1) / BPF_REG_SIZE;
 }
 
 static struct bpf_func_state *func(struct bpf_verifier_env *env,
                                    const struct bpf_reg_state *reg)
 {
         struct bpf_verifier_state *cur = env->cur_state;
 
         return cur->frame[reg->frameno];
 }
 
 static bool is_spi_bounds_valid(struct bpf_func_state *state, int spi, int nr_slots)
 {
        int allocated_slots = state->allocated_stack / BPF_REG_SIZE;
 
        /* We need to check that slots between [spi - nr_slots + 1, spi] are
         * within [0, allocated_stack).
         *
         * Please note that the spi grows downwards. For example, a dynptr
         * takes the size of two stack slots; the first slot will be at
         * spi and the second slot will be at spi - 1.
         */
        return spi - nr_slots + 1 >= 0 && spi < allocated_slots;
 }
 
 static int stack_slot_obj_get_spi(struct bpf_verifier_env *env, struct bpf_reg_state *reg,
                                   const char *obj_kind, int nr_slots)
 {
         int off, spi;
 
         if (!tnum_is_const(reg->var_off)) {
                 verbose(env, "%s has to be at a constant offset\n", obj_kind);
                 return -EINVAL;
         }
 
         off = reg->off + reg->var_off.value;
         if (off % BPF_REG_SIZE) {
                 verbose(env, "cannot pass in %s at an offset=%d\n", obj_kind, off);
                 return -EINVAL;
         }
 
         spi = __get_spi(off);
         if (spi + 1 < nr_slots) {
                 verbose(env, "cannot pass in %s at an offset=%d\n", obj_kind, off);
                 return -EINVAL;
         }
 
         if (!is_spi_bounds_valid(func(env, reg), spi, nr_slots))
                 return -ERANGE;
         return spi;
 }
 
 static int dynptr_get_spi(struct bpf_verifier_env *env, struct bpf_reg_state *reg)
 {
         return stack_slot_obj_get_spi(env, reg, "dynptr", BPF_DYNPTR_NR_SLOTS);
 }
 
 static int iter_get_spi(struct bpf_verifier_env *env, struct bpf_reg_state *reg, int nr_slots)
 {
         return stack_slot_obj_get_spi(env, reg, "iter", nr_slots);
 }
 
 static enum bpf_dynptr_type arg_to_dynptr_type(enum bpf_arg_type arg_type)
 {
         switch (arg_type & DYNPTR_TYPE_FLAG_MASK) {
         case DYNPTR_TYPE_LOCAL:
                 return BPF_DYNPTR_TYPE_LOCAL;
         case DYNPTR_TYPE_RINGBUF:
                 return BPF_DYNPTR_TYPE_RINGBUF;
         case DYNPTR_TYPE_SKB:
                 return BPF_DYNPTR_TYPE_SKB;
         case DYNPTR_TYPE_XDP:
                 return BPF_DYNPTR_TYPE_XDP;
         default:
                 return BPF_DYNPTR_TYPE_INVALID;
         }
 }
 
 static enum bpf_type_flag get_dynptr_type_flag(enum bpf_dynptr_type type)
 {
         switch (type) {
         case BPF_DYNPTR_TYPE_LOCAL:
                 return DYNPTR_TYPE_LOCAL;
         case BPF_DYNPTR_TYPE_RINGBUF:
                 return DYNPTR_TYPE_RINGBUF;
         case BPF_DYNPTR_TYPE_SKB:
                 return DYNPTR_TYPE_SKB;
         case BPF_DYNPTR_TYPE_XDP:
                 return DYNPTR_TYPE_XDP;
         default:
                 return 0;
         }
 }
 
 static bool dynptr_type_refcounted(enum bpf_dynptr_type type)
 {
         return type == BPF_DYNPTR_TYPE_RINGBUF;
 }
 
 static void __mark_dynptr_reg(struct bpf_reg_state *reg,
                               enum bpf_dynptr_type type,
                               bool first_slot, int dynptr_id);
 
 static void __mark_reg_not_init(const struct bpf_verifier_env *env,
                                 struct bpf_reg_state *reg);
 
 static void mark_dynptr_stack_regs(struct bpf_verifier_env *env,
                                    struct bpf_reg_state *sreg1,
                                    struct bpf_reg_state *sreg2,
                                    enum bpf_dynptr_type type)
 {
         int id = ++env->id_gen;
 
         __mark_dynptr_reg(sreg1, type, true, id);
         __mark_dynptr_reg(sreg2, type, false, id);
 }
 
 static void mark_dynptr_cb_reg(struct bpf_verifier_env *env,
                                struct bpf_reg_state *reg,
                                enum bpf_dynptr_type type)
 {
         __mark_dynptr_reg(reg, type, true, ++env->id_gen);
 }
 
 static int destroy_if_dynptr_stack_slot(struct bpf_verifier_env *env,
                                         struct bpf_func_state *state, int spi);
 
 static int mark_stack_slots_dynptr(struct bpf_verifier_env *env, struct bpf_reg_state *reg,
                                    enum bpf_arg_type arg_type, int insn_idx, int clone_ref_obj_id)
 {
         struct bpf_func_state *state = func(env, reg);
         enum bpf_dynptr_type type;
         int spi, i, err;
 
         spi = dynptr_get_spi(env, reg);
         if (spi < 0)
                 return spi;
 
         /* We cannot assume both spi and spi - 1 belong to the same dynptr,
          * hence we need to call destroy_if_dynptr_stack_slot twice for both,
          * to ensure that for the following example:
          *      [d1][d1][d2][d2]
          * spi    3   2   1   0
          * So marking spi = 2 should lead to destruction of both d1 and d2. In
          * case they do belong to same dynptr, second call won't see slot_type
          * as STACK_DYNPTR and will simply skip destruction.
          */
         err = destroy_if_dynptr_stack_slot(env, state, spi);
         if (err)
                 return err;
         err = destroy_if_dynptr_stack_slot(env, state, spi - 1);
         if (err)
                 return err;
 
         for (i = 0; i < BPF_REG_SIZE; i++) {
                 state->stack[spi].slot_type[i] = STACK_DYNPTR;
                 state->stack[spi - 1].slot_type[i] = STACK_DYNPTR;
         }
 
         type = arg_to_dynptr_type(arg_type);
         if (type == BPF_DYNPTR_TYPE_INVALID)
                 return -EINVAL;
 
         mark_dynptr_stack_regs(env, &state->stack[spi].spilled_ptr,
                                &state->stack[spi - 1].spilled_ptr, type);
 
         if (dynptr_type_refcounted(type)) {
                 /* The id is used to track proper releasing */
                 int id;
 
                 if (clone_ref_obj_id)
                         id = clone_ref_obj_id;
                 else
                         id = acquire_reference_state(env, insn_idx);
 
                 if (id < 0)
                         return id;
 
                 state->stack[spi].spilled_ptr.ref_obj_id = id;
                 state->stack[spi - 1].spilled_ptr.ref_obj_id = id;
         }
 
         state->stack[spi].spilled_ptr.live |= REG_LIVE_WRITTEN;
         state->stack[spi - 1].spilled_ptr.live |= REG_LIVE_WRITTEN;
 
         return 0;
 }
 
 static void invalidate_dynptr(struct bpf_verifier_env *env, struct bpf_func_state *state, int spi)
 {
         int i;
 
         for (i = 0; i < BPF_REG_SIZE; i++) {
                 state->stack[spi].slot_type[i] = STACK_INVALID;
                 state->stack[spi - 1].slot_type[i] = STACK_INVALID;
         }
 
         __mark_reg_not_init(env, &state->stack[spi].spilled_ptr);
         __mark_reg_not_init(env, &state->stack[spi - 1].spilled_ptr);
 
         /* Why do we need to set REG_LIVE_WRITTEN for STACK_INVALID slot?
          *
          * While we don't allow reading STACK_INVALID, it is still possible to
          * do <8 byte writes marking some but not all slots as STACK_MISC. Then,
          * helpers or insns can do partial read of that part without failing,
          * but check_stack_range_initialized, check_stack_read_var_off, and
          * check_stack_read_fixed_off will do mark_reg_read for all 8-bytes of
          * the slot conservatively. Hence we need to prevent those liveness
          * marking walks.
          *
          * This was not a problem before because STACK_INVALID is only set by
          * default (where the default reg state has its reg->parent as NULL), or
          * in clean_live_states after REG_LIVE_DONE (at which point
          * mark_reg_read won't walk reg->parent chain), but not randomly during
          * verifier state exploration (like we did above). Hence, for our case
          * parentage chain will still be live (i.e. reg->parent may be
          * non-NULL), while earlier reg->parent was NULL, so we need
          * REG_LIVE_WRITTEN to screen off read marker propagation when it is
          * done later on reads or by mark_dynptr_read as well to unnecessary
          * mark registers in verifier state.
          */
         state->stack[spi].spilled_ptr.live |= REG_LIVE_WRITTEN;
         state->stack[spi - 1].spilled_ptr.live |= REG_LIVE_WRITTEN;
 }
 
 static int unmark_stack_slots_dynptr(struct bpf_verifier_env *env, struct bpf_reg_state *reg)
 {
         struct bpf_func_state *state = func(env, reg);
         int spi, ref_obj_id, i;
 
         spi = dynptr_get_spi(env, reg);
         if (spi < 0)
                 return spi;
 
         if (!dynptr_type_refcounted(state->stack[spi].spilled_ptr.dynptr.type)) {
                 invalidate_dynptr(env, state, spi);
                 return 0;
         }
 
         ref_obj_id = state->stack[spi].spilled_ptr.ref_obj_id;
 
         /* If the dynptr has a ref_obj_id, then we need to invalidate
          * two things:
          *
          * 1) Any dynptrs with a matching ref_obj_id (clones)
          * 2) Any slices derived from this dynptr.
          */
 
         /* Invalidate any slices associated with this dynptr */
         WARN_ON_ONCE(release_reference(env, ref_obj_id));
 
         /* Invalidate any dynptr clones */
         for (i = 1; i < state->allocated_stack / BPF_REG_SIZE; i++) {
                 if (state->stack[i].spilled_ptr.ref_obj_id != ref_obj_id)
                         continue;
 
                 /* it should always be the case that if the ref obj id
                  * matches then the stack slot also belongs to a
                  * dynptr
                  */
                 if (state->stack[i].slot_type[0] != STACK_DYNPTR) {
                         verbose(env, "verifier internal error: misconfigured ref_obj_id\n");
                         return -EFAULT;
                 }
                 if (state->stack[i].spilled_ptr.dynptr.first_slot)
                         invalidate_dynptr(env, state, i);
         }
 
         return 0;
 }
 
 static void __mark_reg_unknown(const struct bpf_verifier_env *env,
                                struct bpf_reg_state *reg);
 
 static void mark_reg_invalid(const struct bpf_verifier_env *env, struct bpf_reg_state *reg)
 {
         if (!env->allow_ptr_leaks)
                 __mark_reg_not_init(env, reg);
         else
                 __mark_reg_unknown(env, reg);
 }
 
 static int destroy_if_dynptr_stack_slot(struct bpf_verifier_env *env,
                                         struct bpf_func_state *state, int spi)
 {
         struct bpf_func_state *fstate;
         struct bpf_reg_state *dreg;
         int i, dynptr_id;
 
         /* We always ensure that STACK_DYNPTR is never set partially,
          * hence just checking for slot_type[0] is enough. This is
          * different for STACK_SPILL, where it may be only set for
          * 1 byte, so code has to use is_spilled_reg.
          */
         if (state->stack[spi].slot_type[0] != STACK_DYNPTR)
                 return 0;
 
         /* Reposition spi to first slot */
         if (!state->stack[spi].spilled_ptr.dynptr.first_slot)
                 spi = spi + 1;
 
         if (dynptr_type_refcounted(state->stack[spi].spilled_ptr.dynptr.type)) {
                 verbose(env, "cannot overwrite referenced dynptr\n");
                 return -EINVAL;
         }
 
         mark_stack_slot_scratched(env, spi);
         mark_stack_slot_scratched(env, spi - 1);
 
         /* Writing partially to one dynptr stack slot destroys both. */
         for (i = 0; i < BPF_REG_SIZE; i++) {
                 state->stack[spi].slot_type[i] = STACK_INVALID;
                 state->stack[spi - 1].slot_type[i] = STACK_INVALID;
         }
 
         dynptr_id = state->stack[spi].spilled_ptr.id;
         /* Invalidate any slices associated with this dynptr */
         bpf_for_each_reg_in_vstate(env->cur_state, fstate, dreg, ({
                 /* Dynptr slices are only PTR_TO_MEM_OR_NULL and PTR_TO_MEM */
                 if (dreg->type != (PTR_TO_MEM | PTR_MAYBE_NULL) && dreg->type != PTR_TO_MEM)
                         continue;
                 if (dreg->dynptr_id == dynptr_id)
                         mark_reg_invalid(env, dreg);
         }));
 
         /* Do not release reference state, we are destroying dynptr on stack,
          * not using some helper to release it. Just reset register.
          */
         __mark_reg_not_init(env, &state->stack[spi].spilled_ptr);
         __mark_reg_not_init(env, &state->stack[spi - 1].spilled_ptr);
 
         /* Same reason as unmark_stack_slots_dynptr above */
         state->stack[spi].spilled_ptr.live |= REG_LIVE_WRITTEN;
         state->stack[spi - 1].spilled_ptr.live |= REG_LIVE_WRITTEN;
 
         return 0;
 }
 
 static bool is_dynptr_reg_valid_uninit(struct bpf_verifier_env *env, struct bpf_reg_state *reg)
 {
         int spi;
 
         if (reg->type == CONST_PTR_TO_DYNPTR)
                 return false;
 
         spi = dynptr_get_spi(env, reg);
 
         /* -ERANGE (i.e. spi not falling into allocated stack slots) isn't an
          * error because this just means the stack state hasn't been updated yet.
          * We will do check_mem_access to check and update stack bounds later.
          */
         if (spi < 0 && spi != -ERANGE)
                 return false;
 
         /* We don't need to check if the stack slots are marked by previous
          * dynptr initializations because we allow overwriting existing unreferenced
          * STACK_DYNPTR slots, see mark_stack_slots_dynptr which calls
          * destroy_if_dynptr_stack_slot to ensure dynptr objects at the slots we are
          * touching are completely destructed before we reinitialize them for a new
          * one. For referenced ones, destroy_if_dynptr_stack_slot returns an error early
          * instead of delaying it until the end where the user will get "Unreleased
          * reference" error.
          */
         return true;
 }
 
 static bool is_dynptr_reg_valid_init(struct bpf_verifier_env *env, struct bpf_reg_state *reg)
 {
         struct bpf_func_state *state = func(env, reg);
         int i, spi;
 
         /* This already represents first slot of initialized bpf_dynptr.
          *
          * CONST_PTR_TO_DYNPTR already has fixed and var_off as 0 due to
          * check_func_arg_reg_off's logic, so we don't need to check its
          * offset and alignment.
          */
         if (reg->type == CONST_PTR_TO_DYNPTR)
                 return true;
 
         spi = dynptr_get_spi(env, reg);
         if (spi < 0)
                 return false;
         if (!state->stack[spi].spilled_ptr.dynptr.first_slot)
                 return false;
 
         for (i = 0; i < BPF_REG_SIZE; i++) {
                 if (state->stack[spi].slot_type[i] != STACK_DYNPTR ||
                     state->stack[spi - 1].slot_type[i] != STACK_DYNPTR)
                         return false;
         }
 
         return true;
 }
 
 static bool is_dynptr_type_expected(struct bpf_verifier_env *env, struct bpf_reg_state *reg,
                                     enum bpf_arg_type arg_type)
 {
         struct bpf_func_state *state = func(env, reg);
         enum bpf_dynptr_type dynptr_type;
         int spi;
 
         /* ARG_PTR_TO_DYNPTR takes any type of dynptr */
         if (arg_type == ARG_PTR_TO_DYNPTR)
                 return true;
 
         dynptr_type = arg_to_dynptr_type(arg_type);
         if (reg->type == CONST_PTR_TO_DYNPTR) {
                 return reg->dynptr.type == dynptr_type;
         } else {
                 spi = dynptr_get_spi(env, reg);
                 if (spi < 0)
                         return false;
                 return state->stack[spi].spilled_ptr.dynptr.type == dynptr_type;
         }
 }
 
 static void __mark_reg_known_zero(struct bpf_reg_state *reg);
 
 static bool in_rcu_cs(struct bpf_verifier_env *env);
 
 static bool is_kfunc_rcu_protected(struct bpf_kfunc_call_arg_meta *meta);
 
 static int mark_stack_slots_iter(struct bpf_verifier_env *env,
                                  struct bpf_kfunc_call_arg_meta *meta,
                                  struct bpf_reg_state *reg, int insn_idx,
                                  struct btf *btf, u32 btf_id, int nr_slots)
 {
         struct bpf_func_state *state = func(env, reg);
         int spi, i, j, id;
 
         spi = iter_get_spi(env, reg, nr_slots);
         if (spi < 0)
                 return spi;
 
         id = acquire_reference_state(env, insn_idx);
         if (id < 0)
                 return id;
 
         for (i = 0; i < nr_slots; i++) {
                 struct bpf_stack_state *slot = &state->stack[spi - i];
                 struct bpf_reg_state *st = &slot->spilled_ptr;
 
                 __mark_reg_known_zero(st);
                 st->type = PTR_TO_STACK; /* we don't have dedicated reg type */
                 if (is_kfunc_rcu_protected(meta)) {
                         if (in_rcu_cs(env))
                                 st->type |= MEM_RCU;
                         else
                                 st->type |= PTR_UNTRUSTED;
                 }
                 st->live |= REG_LIVE_WRITTEN;
                 st->ref_obj_id = i == 0 ? id : 0;
                 st->iter.btf = btf;
                 st->iter.btf_id = btf_id;
                 st->iter.state = BPF_ITER_STATE_ACTIVE;
                 st->iter.depth = 0;
 
                 for (j = 0; j < BPF_REG_SIZE; j++)
                         slot->slot_type[j] = STACK_ITER;
 
                 mark_stack_slot_scratched(env, spi - i);
         }
 
         return 0;
 }
 
 static int unmark_stack_slots_iter(struct bpf_verifier_env *env,
                                    struct bpf_reg_state *reg, int nr_slots)
 {
         struct bpf_func_state *state = func(env, reg);
         int spi, i, j;
 
         spi = iter_get_spi(env, reg, nr_slots);
         if (spi < 0)
                 return spi;
 
         for (i = 0; i < nr_slots; i++) {
                 struct bpf_stack_state *slot = &state->stack[spi - i];
                 struct bpf_reg_state *st = &slot->spilled_ptr;
 
                 if (i == 0)
                         WARN_ON_ONCE(release_reference(env, st->ref_obj_id));
 
                 __mark_reg_not_init(env, st);
 
                 /* see unmark_stack_slots_dynptr() for why we need to set REG_LIVE_WRITTEN */
                 st->live |= REG_LIVE_WRITTEN;
 
                 for (j = 0; j < BPF_REG_SIZE; j++)
                         slot->slot_type[j] = STACK_INVALID;
 
                 mark_stack_slot_scratched(env, spi - i);
         }
 
         return 0;
 }
 
 static bool is_iter_reg_valid_uninit(struct bpf_verifier_env *env,
                                      struct bpf_reg_state *reg, int nr_slots)
 {
         struct bpf_func_state *state = func(env, reg);
         int spi, i, j;
 
         /* For -ERANGE (i.e. spi not falling into allocated stack slots), we
          * will do check_mem_access to check and update stack bounds later, so
          * return true for that case.
          */
         spi = iter_get_spi(env, reg, nr_slots);
         if (spi == -ERANGE)
                 return true;
         if (spi < 0)
                 return false;
 
         for (i = 0; i < nr_slots; i++) {
                 struct bpf_stack_state *slot = &state->stack[spi - i];
 
                 for (j = 0; j < BPF_REG_SIZE; j++)
                         if (slot->slot_type[j] == STACK_ITER)
                                 return false;
         }
 
         return true;
 }
 
 static int is_iter_reg_valid_init(struct bpf_verifier_env *env, struct bpf_reg_state *reg,
                                    struct btf *btf, u32 btf_id, int nr_slots)
 {
         struct bpf_func_state *state = func(env, reg);
         int spi, i, j;
 
         spi = iter_get_spi(env, reg, nr_slots);
         if (spi < 0)
                 return -EINVAL;
 
         for (i = 0; i < nr_slots; i++) {
                 struct bpf_stack_state *slot = &state->stack[spi - i];
                 struct bpf_reg_state *st = &slot->spilled_ptr;
 
                 if (st->type & PTR_UNTRUSTED)
                         return -EPROTO;
                 /* only main (first) slot has ref_obj_id set */
                 if (i == 0 && !st->ref_obj_id)
                         return -EINVAL;
                 if (i != 0 && st->ref_obj_id)
                         return -EINVAL;
                 if (st->iter.btf != btf || st->iter.btf_id != btf_id)
                         return -EINVAL;
 
                 for (j = 0; j < BPF_REG_SIZE; j++)
                         if (slot->slot_type[j] != STACK_ITER)
                                 return -EINVAL;
         }
 
         return 0;
 }
 
 /* Check if given stack slot is "special":
  *   - spilled register state (STACK_SPILL);
  *   - dynptr state (STACK_DYNPTR);
  *   - iter state (STACK_ITER).
  */
 static bool is_stack_slot_special(const struct bpf_stack_state *stack)
 {
         enum bpf_stack_slot_type type = stack->slot_type[BPF_REG_SIZE - 1];
 
         switch (type) {
         case STACK_SPILL:
         case STACK_DYNPTR:
         case STACK_ITER:
                 return true;
         case STACK_INVALID:
         case STACK_MISC:
         case STACK_ZERO:
                 return false;
         default:
                 WARN_ONCE(1, "unknown stack slot type %d\n", type);
                 return true;
         }
 }
 
 /* The reg state of a pointer or a bounded scalar was saved when
  * it was spilled to the stack.
  */
 static bool is_spilled_reg(const struct bpf_stack_state *stack)
 {
         return stack->slot_type[BPF_REG_SIZE - 1] == STACK_SPILL;
 }
 
 static bool is_spilled_scalar_reg(const struct bpf_stack_state *stack)
 {
         return stack->slot_type[BPF_REG_SIZE - 1] == STACK_SPILL &&
                stack->spilled_ptr.type == SCALAR_VALUE;
 }
 
 static bool is_spilled_scalar_reg64(const struct bpf_stack_state *stack)
 {
         return stack->slot_type[0] == STACK_SPILL &&
                stack->spilled_ptr.type == SCALAR_VALUE;
 }
 
 /* Mark stack slot as STACK_MISC, unless it is already STACK_INVALID, in which
  * case they are equivalent, or it's STACK_ZERO, in which case we preserve
  * more precise STACK_ZERO.
  * Note, in uprivileged mode leaving STACK_INVALID is wrong, so we take
  * env->allow_ptr_leaks into account and force STACK_MISC, if necessary.
  */
 static void mark_stack_slot_misc(struct bpf_verifier_env *env, u8 *stype)
 {
         if (*stype == STACK_ZERO)
                 return;
         if (env->allow_ptr_leaks && *stype == STACK_INVALID)
                 return;
         *stype = STACK_MISC;
 }
 
 static void scrub_spilled_slot(u8 *stype)
 {
         if (*stype != STACK_INVALID)
                 *stype = STACK_MISC;
 }
 
 /* copy array src of length n * size bytes to dst. dst is reallocated if it's too
  * small to hold src. This is different from krealloc since we don't want to preserve
  * the contents of dst.
  *
  * Leaves dst untouched if src is NULL or length is zero. Returns NULL if memory could
  * not be allocated.
  */
 static void *copy_array(void *dst, const void *src, size_t n, size_t size, gfp_t flags)
 {
         size_t alloc_bytes;
         void *orig = dst;
         size_t bytes;
 
         if (ZERO_OR_NULL_PTR(src))
                 goto out;
 
         if (unlikely(check_mul_overflow(n, size, &bytes)))
                 return NULL;
 
         alloc_bytes = max(ksize(orig), kmalloc_size_roundup(bytes));
         dst = krealloc(orig, alloc_bytes, flags);
         if (!dst) {
                 kfree(orig);
                 return NULL;
         }
 
         memcpy(dst, src, bytes);
 out:
         return dst ? dst : ZERO_SIZE_PTR;
 }
 
 /* resize an array from old_n items to new_n items. the array is reallocated if it's too
  * small to hold new_n items. new items are zeroed out if the array grows.
  *
  * Contrary to krealloc_array, does not free arr if new_n is zero.
  */
 static void *realloc_array(void *arr, size_t old_n, size_t new_n, size_t size)
 {
         size_t alloc_size;
         void *new_arr;
 
         if (!new_n || old_n == new_n)
                 goto out;
 
         alloc_size = kmalloc_size_roundup(size_mul(new_n, size));
         new_arr = krealloc(arr, alloc_size, GFP_KERNEL);
         if (!new_arr) {
                 kfree(arr);
                 return NULL;
         }
         arr = new_arr;
 
         if (new_n > old_n)
                 memset(arr + old_n * size, 0, (new_n - old_n) * size);
 
 out:
         return arr ? arr : ZERO_SIZE_PTR;
 }
 
 static int copy_reference_state(struct bpf_func_state *dst, const struct bpf_func_state *src)
 {
         dst->refs = copy_array(dst->refs, src->refs, src->acquired_refs,
                                sizeof(struct bpf_reference_state), GFP_KERNEL);
         if (!dst->refs)
                 return -ENOMEM;
 
         dst->acquired_refs = src->acquired_refs;
         return 0;
 }
 
 static int copy_stack_state(struct bpf_func_state *dst, const struct bpf_func_state *src)
 {
         size_t n = src->allocated_stack / BPF_REG_SIZE;
 
         dst->stack = copy_array(dst->stack, src->stack, n, sizeof(struct bpf_stack_state),
                                 GFP_KERNEL);
         if (!dst->stack)
                 return -ENOMEM;
 
         dst->allocated_stack = src->allocated_stack;
         return 0;
 }
 
 static int resize_reference_state(struct bpf_func_state *state, size_t n)
 {
         state->refs = realloc_array(state->refs, state->acquired_refs, n,
                                     sizeof(struct bpf_reference_state));
         if (!state->refs)
                 return -ENOMEM;
 
         state->acquired_refs = n;
         return 0;
 }
 
 /* Possibly update state->allocated_stack to be at least size bytes. Also
  * possibly update the function's high-water mark in its bpf_subprog_info.
  */
 static int grow_stack_state(struct bpf_verifier_env *env, struct bpf_func_state *state, int size)
 {
         size_t old_n = state->allocated_stack / BPF_REG_SIZE, n;
 
         /* The stack size is always a multiple of BPF_REG_SIZE. */
         size = round_up(size, BPF_REG_SIZE);
         n = size / BPF_REG_SIZE;
 
         if (old_n >= n)
                 return 0;
 
         state->stack = realloc_array(state->stack, old_n, n, sizeof(struct bpf_stack_state));
         if (!state->stack)
                 return -ENOMEM;
 
         state->allocated_stack = size;
 
         /* update known max for given subprogram */
         if (env->subprog_info[state->subprogno].stack_depth < size)
                 env->subprog_info[state->subprogno].stack_depth = size;
 
         return 0;
 }
 
 /* Acquire a pointer id from the env and update the state->refs to include
  * this new pointer reference.
  * On success, returns a valid pointer id to associate with the register
  * On failure, returns a negative errno.
  */
 static int acquire_reference_state(struct bpf_verifier_env *env, int insn_idx)
 {
         struct bpf_func_state *state = cur_func(env);
         int new_ofs = state->acquired_refs;
         int id, err;
 
         err = resize_reference_state(state, state->acquired_refs + 1);
         if (err)
                 return err;
         id = ++env->id_gen;
         state->refs[new_ofs].id = id;
         state->refs[new_ofs].insn_idx = insn_idx;
         state->refs[new_ofs].callback_ref = state->in_callback_fn ? state->frameno : 0;
 
         return id;
 }
 
 /* release function corresponding to acquire_reference_state(). Idempotent. */
 static int release_reference_state(struct bpf_func_state *state, int ptr_id)
 {
         int i, last_idx;
 
         last_idx = state->acquired_refs - 1;
         for (i = 0; i < state->acquired_refs; i++) {
                 if (state->refs[i].id == ptr_id) {
                         /* Cannot release caller references in callbacks */
                         if (state->in_callback_fn && state->refs[i].callback_ref != state->frameno)
                                 return -EINVAL;
                         if (last_idx && i != last_idx)
                                 memcpy(&state->refs[i], &state->refs[last_idx],
                                        sizeof(*state->refs));
                         memset(&state->refs[last_idx], 0, sizeof(*state->refs));
                         state->acquired_refs--;
                         return 0;
                 }
         }
         return -EINVAL;
 }
 
 static void free_func_state(struct bpf_func_state *state)
 {
         if (!state)
                 return;
         kfree(state->refs);
         kfree(state->stack);
         kfree(state);
 }
 
 static void clear_jmp_history(struct bpf_verifier_state *state)
 {
         kfree(state->jmp_history);
         state->jmp_history = NULL;
         state->jmp_history_cnt = 0;
 }
 
 static void free_verifier_state(struct bpf_verifier_state *state,
                                 bool free_self)
 {
         int i;
 
         for (i = 0; i <= state->curframe; i++) {
                 free_func_state(state->frame[i]);
                 state->frame[i] = NULL;
         }
         clear_jmp_history(state);
         if (free_self)
                 kfree(state);
 }
 
 /* copy verifier state from src to dst growing dst stack space
  * when necessary to accommodate larger src stack
  */
 static int copy_func_state(struct bpf_func_state *dst,
                            const struct bpf_func_state *src)
 {
         int err;
 
         memcpy(dst, src, offsetof(struct bpf_func_state, acquired_refs));
         err = copy_reference_state(dst, src);
         if (err)
                 return err;
         return copy_stack_state(dst, src);
 }
 
 static int copy_verifier_state(struct bpf_verifier_state *dst_state,
                                const struct bpf_verifier_state *src)
 {
         struct bpf_func_state *dst;
         int i, err;
 
         dst_state->jmp_history = copy_array(dst_state->jmp_history, src->jmp_history,
                                           src->jmp_history_cnt, sizeof(*dst_state->jmp_history),
                                           GFP_USER);
         if (!dst_state->jmp_history)
                 return -ENOMEM;
         dst_state->jmp_history_cnt = src->jmp_history_cnt;
 
         /* if dst has more stack frames then src frame, free them, this is also
          * necessary in case of exceptional exits using bpf_throw.
          */
         for (i = src->curframe + 1; i <= dst_state->curframe; i++) {
                 free_func_state(dst_state->frame[i]);
                 dst_state->frame[i] = NULL;
         }
         dst_state->speculative = src->speculative;
         dst_state->active_rcu_lock = src->active_rcu_lock;
         dst_state->active_preempt_lock = src->active_preempt_lock;
         dst_state->in_sleepable = src->in_sleepable;
         dst_state->curframe = src->curframe;
         dst_state->active_lock.ptr = src->active_lock.ptr;
         dst_state->active_lock.id = src->active_lock.id;
         dst_state->branches = src->branches;
         dst_state->parent = src->parent;
         dst_state->first_insn_idx = src->first_insn_idx;
         dst_state->last_insn_idx = src->last_insn_idx;
         dst_state->dfs_depth = src->dfs_depth;
         dst_state->callback_unroll_depth = src->callback_unroll_depth;
         dst_state->used_as_loop_entry = src->used_as_loop_entry;
         dst_state->may_goto_depth = src->may_goto_depth;
         for (i = 0; i <= src->curframe; i++) {
                 dst = dst_state->frame[i];
                 if (!dst) {
                         dst = kzalloc(sizeof(*dst), GFP_KERNEL);
                         if (!dst)
                                 return -ENOMEM;
                         dst_state->frame[i] = dst;
                 }
                 err = copy_func_state(dst, src->frame[i]);
                 if (err)
                         return err;
         }
         return 0;
 }
 
 static u32 state_htab_size(struct bpf_verifier_env *env)
 {
         return env->prog->len;
 }
 
 static struct bpf_verifier_state_list **explored_state(struct bpf_verifier_env *env, int idx)
 {
         struct bpf_verifier_state *cur = env->cur_state;
         struct bpf_func_state *state = cur->frame[cur->curframe];
 
         return &env->explored_states[(idx ^ state->callsite) % state_htab_size(env)];
 }
 
 static bool same_callsites(struct bpf_verifier_state *a, struct bpf_verifier_state *b)
 {
         int fr;
 
         if (a->curframe != b->curframe)
                 return false;
 
         for (fr = a->curframe; fr >= 0; fr--)
                 if (a->frame[fr]->callsite != b->frame[fr]->callsite)
                         return false;
 
         return true;
 }
 
 /* Open coded iterators allow back-edges in the state graph in order to
  * check unbounded loops that iterators.
  *
  * In is_state_visited() it is necessary to know if explored states are
  * part of some loops in order to decide whether non-exact states
  * comparison could be used:
  * - non-exact states comparison establishes sub-state relation and uses
  *   read and precision marks to do so, these marks are propagated from
  *   children states and thus are not guaranteed to be final in a loop;
  * - exact states comparison just checks if current and explored states
  *   are identical (and thus form a back-edge).
  *
  * Paper "A New Algorithm for Identifying Loops in Decompilation"
  * by Tao Wei, Jian Mao, Wei Zou and Yu Chen [1] presents a convenient
  * algorithm for loop structure detection and gives an overview of
  * relevant terminology. It also has helpful illustrations.
  *
  * [1] https://api.semanticscholar.org/CorpusID:15784067
  *
  * We use a similar algorithm but because loop nested structure is
  * irrelevant for verifier ours is significantly simpler and resembles
  * strongly connected components algorithm from Sedgewick's textbook.
  *
  * Define topmost loop entry as a first node of the loop traversed in a
  * depth first search starting from initial state. The goal of the loop
  * tracking algorithm is to associate topmost loop entries with states
  * derived from these entries.
  *
  * For each step in the DFS states traversal algorithm needs to identify
  * the following situations:
  *
  *          initial                     initial                   initial
  *            |                           |                         |
  *            V                           V                         V
  *           ...                         ...           .---------> hdr
  *            |                           |            |            |
  *            V                           V            |            V
  *           cur                     .-> succ          |    .------...
  *            |                      |    |            |    |       |
  *            V                      |    V            |    V       V
  *           succ                    '-- cur           |   ...     ...
  *                                                     |    |       |
  *                                                     |    V       V
  *                                                     |   succ <- cur
  *                                                     |    |
  *                                                     |    V
  *                                                     |   ...
  *                                                     |    |
  *                                                     '----'
  *
  *  (A) successor state of cur   (B) successor state of cur or it's entry
  *      not yet traversed            are in current DFS path, thus cur and succ
  *                                   are members of the same outermost loop
  *
  *                      initial                  initial
  *                        |                        |
  *                        V                        V
  *                       ...                      ...
  *                        |                        |
  *                        V                        V
  *                .------...               .------...
  *                |       |                |       |
  *                V       V                V       V
  *           .-> hdr     ...              ...     ...
  *           |    |       |                |       |
  *           |    V       V                V       V
  *           |   succ <- cur              succ <- cur
  *           |    |                        |
  *           |    V                        V
  *           |   ...                      ...
  *           |    |                        |
  *           '----'                       exit
  *
  * (C) successor state of cur is a part of some loop but this loop
  *     does not include cur or successor state is not in a loop at all.
  *
  * Algorithm could be described as the following python code:
  *
  *     traversed = set()   # Set of traversed nodes
  *     entries = {}        # Mapping from node to loop entry
  *     depths = {}         # Depth level assigned to graph node
  *     path = set()        # Current DFS path
  *
  *     # Find outermost loop entry known for n
  *     def get_loop_entry(n):
  *         h = entries.get(n, None)
  *         while h in entries and entries[h] != h:
  *             h = entries[h]
  *         return h
  *
  *     # Update n's loop entry if h's outermost entry comes
  *     # before n's outermost entry in current DFS path.
  *     def update_loop_entry(n, h):
  *         n1 = get_loop_entry(n) or n
  *         h1 = get_loop_entry(h) or h
  *         if h1 in path and depths[h1] <= depths[n1]:
  *             entries[n] = h1
  *
  *     def dfs(n, depth):
  *         traversed.add(n)
  *         path.add(n)
  *         depths[n] = depth
  *         for succ in G.successors(n):
  *             if succ not in traversed:
  *                 # Case A: explore succ and update cur's loop entry
  *                 #         only if succ's entry is in current DFS path.
  *                 dfs(succ, depth + 1)
  *                 h = get_loop_entry(succ)
  *                 update_loop_entry(n, h)
  *             else:
  *                 # Case B or C depending on `h1 in path` check in update_loop_entry().
  *                 update_loop_entry(n, succ)
  *         path.remove(n)
  *
  * To adapt this algorithm for use with verifier:
  * - use st->branch == 0 as a signal that DFS of succ had been finished
  *   and cur's loop entry has to be updated (case A), handle this in
  *   update_branch_counts();
  * - use st->branch > 0 as a signal that st is in the current DFS path;
  * - handle cases B and C in is_state_visited();
  * - update topmost loop entry for intermediate states in get_loop_entry().
  */
 static struct bpf_verifier_state *get_loop_entry(struct bpf_verifier_state *st)
 {
         struct bpf_verifier_state *topmost = st->loop_entry, *old;
 
         while (topmost && topmost->loop_entry && topmost != topmost->loop_entry)
                 topmost = topmost->loop_entry;
         /* Update loop entries for intermediate states to avoid this
          * traversal in future get_loop_entry() calls.
          */
         while (st && st->loop_entry != topmost) {
                 old = st->loop_entry;
                 st->loop_entry = topmost;
                 st = old;
         }
         return topmost;
 }
 
 static void update_loop_entry(struct bpf_verifier_state *cur, struct bpf_verifier_state *hdr)
 {
         struct bpf_verifier_state *cur1, *hdr1;
 
         cur1 = get_loop_entry(cur) ?: cur;
         hdr1 = get_loop_entry(hdr) ?: hdr;
         /* The head1->branches check decides between cases B and C in
          * comment for get_loop_entry(). If hdr1->branches == 0 then
          * head's topmost loop entry is not in current DFS path,
          * hence 'cur' and 'hdr' are not in the same loop and there is
          * no need to update cur->loop_entry.
          */
         if (hdr1->branches && hdr1->dfs_depth <= cur1->dfs_depth) {
                 cur->loop_entry = hdr;
                 hdr->used_as_loop_entry = true;
         }
 }
 
 static void update_branch_counts(struct bpf_verifier_env *env, struct bpf_verifier_state *st)
 {
         while (st) {
                 u32 br = --st->branches;
 
                 /* br == 0 signals that DFS exploration for 'st' is finished,
                  * thus it is necessary to update parent's loop entry if it
                  * turned out that st is a part of some loop.
                  * This is a part of 'case A' in get_loop_entry() comment.
                  */
                 if (br == 0 && st->parent && st->loop_entry)
                         update_loop_entry(st->parent, st->loop_entry);
 
                 /* WARN_ON(br > 1) technically makes sense here,
                  * but see comment in push_stack(), hence:
                  */
                 WARN_ONCE((int)br < 0,
                           "BUG update_branch_counts:branches_to_explore=%d\n",
                           br);
                 if (br)
                         break;
                 st = st->parent;
         }
 }
 
 static int pop_stack(struct bpf_verifier_env *env, int *prev_insn_idx,
                      int *insn_idx, bool pop_log)
 {
         struct bpf_verifier_state *cur = env->cur_state;
         struct bpf_verifier_stack_elem *elem, *head = env->head;
         int err;
 
         if (env->head == NULL)
                 return -ENOENT;
 
         if (cur) {
                 err = copy_verifier_state(cur, &head->st);
                 if (err)
                         return err;
         }
         if (pop_log)
                 bpf_vlog_reset(&env->log, head->log_pos);
         if (insn_idx)
                 *insn_idx = head->insn_idx;
         if (prev_insn_idx)
                 *prev_insn_idx = head->prev_insn_idx;
         elem = head->next;
         free_verifier_state(&head->st, false);
         kfree(head);
         env->head = elem;
         env->stack_size--;
         return 0;
 }
 
 static struct bpf_verifier_state *push_stack(struct bpf_verifier_env *env,
                                              int insn_idx, int prev_insn_idx,
                                              bool speculative)
 {
         struct bpf_verifier_state *cur = env->cur_state;
         struct bpf_verifier_stack_elem *elem;
         int err;
 
         elem = kzalloc(sizeof(struct bpf_verifier_stack_elem), GFP_KERNEL);
         if (!elem)
                 goto err;
 
         elem->insn_idx = insn_idx;
         elem->prev_insn_idx = prev_insn_idx;
         elem->next = env->head;
         elem->log_pos = env->log.end_pos;
         env->head = elem;
         env->stack_size++;
         err = copy_verifier_state(&elem->st, cur);
         if (err)
                 goto err;
         elem->st.speculative |= speculative;
         if (env->stack_size > BPF_COMPLEXITY_LIMIT_JMP_SEQ) {
                 verbose(env, "The sequence of %d jumps is too complex.\n",
                         env->stack_size);
                 goto err;
         }
         if (elem->st.parent) {
                 ++elem->st.parent->branches;
                 /* WARN_ON(branches > 2) technically makes sense here,
                  * but
                  * 1. speculative states will bump 'branches' for non-branch
                  * instructions
                  * 2. is_state_visited() heuristics may decide not to create
                  * a new state for a sequence of branches and all such current
                  * and cloned states will be pointing to a single parent state
                  * which might have large 'branches' count.
                  */
         }
         return &elem->st;
 err:
         free_verifier_state(env->cur_state, true);
         env->cur_state = NULL;
         /* pop all elements and return */
         while (!pop_stack(env, NULL, NULL, false));
         return NULL;
 }
 
 #define CALLER_SAVED_REGS 6
 static const int caller_saved[CALLER_SAVED_REGS] = {
         BPF_REG_0, BPF_REG_1, BPF_REG_2, BPF_REG_3, BPF_REG_4, BPF_REG_5
 };
 
 /* This helper doesn't clear reg->id */
 static void ___mark_reg_known(struct bpf_reg_state *reg, u64 imm)
 {
         reg->var_off = tnum_const(imm);
         reg->smin_value = (s64)imm;
         reg->smax_value = (s64)imm;
         reg->umin_value = imm;
         reg->umax_value = imm;
 
         reg->s32_min_value = (s32)imm;
         reg->s32_max_value = (s32)imm;
         reg->u32_min_value = (u32)imm;
         reg->u32_max_value = (u32)imm;
 }
 
 /* Mark the unknown part of a register (variable offset or scalar value) as
  * known to have the value @imm.
  */
 static void __mark_reg_known(struct bpf_reg_state *reg, u64 imm)
 {
         /* Clear off and union(map_ptr, range) */
         memset(((u8 *)reg) + sizeof(reg->type), 0,
                offsetof(struct bpf_reg_state, var_off) - sizeof(reg->type));
         reg->id = 0;
         reg->ref_obj_id = 0;
         ___mark_reg_known(reg, imm);
 }
 
 static void __mark_reg32_known(struct bpf_reg_state *reg, u64 imm)
 {
         reg->var_off = tnum_const_subreg(reg->var_off, imm);
         reg->s32_min_value = (s32)imm;
         reg->s32_max_value = (s32)imm;
         reg->u32_min_value = (u32)imm;
         reg->u32_max_value = (u32)imm;
 }
 
 /* Mark the 'variable offset' part of a register as zero.  This should be
  * used only on registers holding a pointer type.
  */
 static void __mark_reg_known_zero(struct bpf_reg_state *reg)
 {
         __mark_reg_known(reg, 0);
 }
 
 static void __mark_reg_const_zero(const struct bpf_verifier_env *env, struct bpf_reg_state *reg)
 {
         __mark_reg_known(reg, 0);
         reg->type = SCALAR_VALUE;
         /* all scalars are assumed imprecise initially (unless unprivileged,
          * in which case everything is forced to be precise)
          */
         reg->precise = !env->bpf_capable;
 }
 
 static void mark_reg_known_zero(struct bpf_verifier_env *env,
                                 struct bpf_reg_state *regs, u32 regno)
 {
         if (WARN_ON(regno >= MAX_BPF_REG)) {
                 verbose(env, "mark_reg_known_zero(regs, %u)\n", regno);
                 /* Something bad happened, let's kill all regs */
                 for (regno = 0; regno < MAX_BPF_REG; regno++)
                         __mark_reg_not_init(env, regs + regno);
                 return;
         }
         __mark_reg_known_zero(regs + regno);
 }
 
 static void __mark_dynptr_reg(struct bpf_reg_state *reg, enum bpf_dynptr_type type,
                               bool first_slot, int dynptr_id)
 {
         /* reg->type has no meaning for STACK_DYNPTR, but when we set reg for
          * callback arguments, it does need to be CONST_PTR_TO_DYNPTR, so simply
          * set it unconditionally as it is ignored for STACK_DYNPTR anyway.
          */
         __mark_reg_known_zero(reg);
         reg->type = CONST_PTR_TO_DYNPTR;
         /* Give each dynptr a unique id to uniquely associate slices to it. */
         reg->id = dynptr_id;
         reg->dynptr.type = type;
         reg->dynptr.first_slot = first_slot;
 }
 
 static void mark_ptr_not_null_reg(struct bpf_reg_state *reg)
 {
         if (base_type(reg->type) == PTR_TO_MAP_VALUE) {
                 const struct bpf_map *map = reg->map_ptr;
 
                 if (map->inner_map_meta) {
                         reg->type = CONST_PTR_TO_MAP;
                         reg->map_ptr = map->inner_map_meta;
                         /* transfer reg's id which is unique for every map_lookup_elem
                          * as UID of the inner map.
                          */
                         if (btf_record_has_field(map->inner_map_meta->record, BPF_TIMER))
                                 reg->map_uid = reg->id;
                         if (btf_record_has_field(map->inner_map_meta->record, BPF_WORKQUEUE))
                                 reg->map_uid = reg->id;
                 } else if (map->map_type == BPF_MAP_TYPE_XSKMAP) {
                         reg->type = PTR_TO_XDP_SOCK;
                 } else if (map->map_type == BPF_MAP_TYPE_SOCKMAP ||
                            map->map_type == BPF_MAP_TYPE_SOCKHASH) {
                         reg->type = PTR_TO_SOCKET;
                 } else {
                         reg->type = PTR_TO_MAP_VALUE;
                 }
                 return;
         }
 
         reg->type &= ~PTR_MAYBE_NULL;
 }
 
 static void mark_reg_graph_node(struct bpf_reg_state *regs, u32 regno,
                                 struct btf_field_graph_root *ds_head)
 {
         __mark_reg_known_zero(&regs[regno]);
         regs[regno].type = PTR_TO_BTF_ID | MEM_ALLOC;
         regs[regno].btf = ds_head->btf;
         regs[regno].btf_id = ds_head->value_btf_id;
         regs[regno].off = ds_head->node_offset;
 }
 
 static bool reg_is_pkt_pointer(const struct bpf_reg_state *reg)
 {
         return type_is_pkt_pointer(reg->type);
 }
 
 static bool reg_is_pkt_pointer_any(const struct bpf_reg_state *reg)
 {
         return reg_is_pkt_pointer(reg) ||
                reg->type == PTR_TO_PACKET_END;
 }
 
 static bool reg_is_dynptr_slice_pkt(const struct bpf_reg_state *reg)
 {
         return base_type(reg->type) == PTR_TO_MEM &&
                 (reg->type & DYNPTR_TYPE_SKB || reg->type & DYNPTR_TYPE_XDP);
 }
 
 /* Unmodified PTR_TO_PACKET[_META,_END] register from ctx access. */
 static bool reg_is_init_pkt_pointer(const struct bpf_reg_state *reg,
                                     enum bpf_reg_type which)
 {
         /* The register can already have a range from prior markings.
          * This is fine as long as it hasn't been advanced from its
          * origin.
          */
         return reg->type == which &&
                reg->id == 0 &&
                reg->off == 0 &&
                tnum_equals_const(reg->var_off, 0);
 }
 
 /* Reset the min/max bounds of a register */
 static void __mark_reg_unbounded(struct bpf_reg_state *reg)
 {
         reg->smin_value = S64_MIN;
         reg->smax_value = S64_MAX;
         reg->umin_value = 0;
         reg->umax_value = U64_MAX;
 
         reg->s32_min_value = S32_MIN;
         reg->s32_max_value = S32_MAX;
         reg->u32_min_value = 0;
         reg->u32_max_value = U32_MAX;
 }
 
 static void __mark_reg64_unbounded(struct bpf_reg_state *reg)
 {
         reg->smin_value = S64_MIN;
         reg->smax_value = S64_MAX;
         reg->umin_value = 0;
         reg->umax_value = U64_MAX;
 }
 
 static void __mark_reg32_unbounded(struct bpf_reg_state *reg)
 {
         reg->s32_min_value = S32_MIN;
         reg->s32_max_value = S32_MAX;
         reg->u32_min_value = 0;
         reg->u32_max_value = U32_MAX;
 }
 
 static void __update_reg32_bounds(struct bpf_reg_state *reg)
 {
         struct tnum var32_off = tnum_subreg(reg->var_off);
 
         /* min signed is max(sign bit) | min(other bits) */
         reg->s32_min_value = max_t(s32, reg->s32_min_value,
                         var32_off.value | (var32_off.mask & S32_MIN));
         /* max signed is min(sign bit) | max(other bits) */
         reg->s32_max_value = min_t(s32, reg->s32_max_value,
                         var32_off.value | (var32_off.mask & S32_MAX));
         reg->u32_min_value = max_t(u32, reg->u32_min_value, (u32)var32_off.value);
         reg->u32_max_value = min(reg->u32_max_value,
                                  (u32)(var32_off.value | var32_off.mask));
 }
 
 static void __update_reg64_bounds(struct bpf_reg_state *reg)
 {
         /* min signed is max(sign bit) | min(other bits) */
         reg->smin_value = max_t(s64, reg->smin_value,
                                 reg->var_off.value | (reg->var_off.mask & S64_MIN));
         /* max signed is min(sign bit) | max(other bits) */
         reg->smax_value = min_t(s64, reg->smax_value,
                                 reg->var_off.value | (reg->var_off.mask & S64_MAX));
         reg->umin_value = max(reg->umin_value, reg->var_off.value);
         reg->umax_value = min(reg->umax_value,
                               reg->var_off.value | reg->var_off.mask);
 }
 
 static void __update_reg_bounds(struct bpf_reg_state *reg)
 {
         __update_reg32_bounds(reg);
         __update_reg64_bounds(reg);
 }
 
 /* Uses signed min/max values to inform unsigned, and vice-versa */
 static void __reg32_deduce_bounds(struct bpf_reg_state *reg)
 {
         /* If upper 32 bits of u64/s64 range don't change, we can use lower 32
          * bits to improve our u32/s32 boundaries.
          *
          * E.g., the case where we have upper 32 bits as zero ([10, 20] in
          * u64) is pretty trivial, it's obvious that in u32 we'll also have
          * [10, 20] range. But this property holds for any 64-bit range as
          * long as upper 32 bits in that entire range of values stay the same.
          *
          * E.g., u64 range [0x10000000A, 0x10000000F] ([4294967306, 4294967311]
          * in decimal) has the same upper 32 bits throughout all the values in
          * that range. As such, lower 32 bits form a valid [0xA, 0xF] ([10, 15])
          * range.
          *
          * Note also, that [0xA, 0xF] is a valid range both in u32 and in s32,
          * following the rules outlined below about u64/s64 correspondence
          * (which equally applies to u32 vs s32 correspondence). In general it
          * depends on actual hexadecimal values of 32-bit range. They can form
          * only valid u32, or only valid s32 ranges in some cases.
          *
          * So we use all these insights to derive bounds for subregisters here.
          */
         if ((reg->umin_value >> 32) == (reg->umax_value >> 32)) {
                 /* u64 to u32 casting preserves validity of low 32 bits as
                  * a range, if upper 32 bits are the same
                  */
                 reg->u32_min_value = max_t(u32, reg->u32_min_value, (u32)reg->umin_value);
                 reg->u32_max_value = min_t(u32, reg->u32_max_value, (u32)reg->umax_value);
 
                 if ((s32)reg->umin_value <= (s32)reg->umax_value) {
                         reg->s32_min_value = max_t(s32, reg->s32_min_value, (s32)reg->umin_value);
                         reg->s32_max_value = min_t(s32, reg->s32_max_value, (s32)reg->umax_value);
                 }
         }
         if ((reg->smin_value >> 32) == (reg->smax_value >> 32)) {
                 /* low 32 bits should form a proper u32 range */
                 if ((u32)reg->smin_value <= (u32)reg->smax_value) {
                         reg->u32_min_value = max_t(u32, reg->u32_min_value, (u32)reg->smin_value);
                         reg->u32_max_value = min_t(u32, reg->u32_max_value, (u32)reg->smax_value);
                 }
                 /* low 32 bits should form a proper s32 range */
                 if ((s32)reg->smin_value <= (s32)reg->smax_value) {
                         reg->s32_min_value = max_t(s32, reg->s32_min_value, (s32)reg->smin_value);
                         reg->s32_max_value = min_t(s32, reg->s32_max_value, (s32)reg->smax_value);
                 }
         }
         /* Special case where upper bits form a small sequence of two
          * sequential numbers (in 32-bit unsigned space, so 0xffffffff to
          * 0x00000000 is also valid), while lower bits form a proper s32 range
          * going from negative numbers to positive numbers. E.g., let's say we
          * have s64 range [-1, 1] ([0xffffffffffffffff, 0x0000000000000001]).
          * Possible s64 values are {-1, 0, 1} ({0xffffffffffffffff,
          * 0x0000000000000000, 0x00000000000001}). Ignoring upper 32 bits,
          * we still get a valid s32 range [-1, 1] ([0xffffffff, 0x00000001]).
          * Note that it doesn't have to be 0xffffffff going to 0x00000000 in
          * upper 32 bits. As a random example, s64 range
          * [0xfffffff0fffffff0; 0xfffffff100000010], forms a valid s32 range
          * [-16, 16] ([0xfffffff0; 0x00000010]) in its 32 bit subregister.
          */
         if ((u32)(reg->umin_value >> 32) + 1 == (u32)(reg->umax_value >> 32) &&
             (s32)reg->umin_value < 0 && (s32)reg->umax_value >= 0) {
                 reg->s32_min_value = max_t(s32, reg->s32_min_value, (s32)reg->umin_value);
                 reg->s32_max_value = min_t(s32, reg->s32_max_value, (s32)reg->umax_value);
         }
         if ((u32)(reg->smin_value >> 32) + 1 == (u32)(reg->smax_value >> 32) &&
             (s32)reg->smin_value < 0 && (s32)reg->smax_value >= 0) {
                 reg->s32_min_value = max_t(s32, reg->s32_min_value, (s32)reg->smin_value);
                 reg->s32_max_value = min_t(s32, reg->s32_max_value, (s32)reg->smax_value);
         }
         /* if u32 range forms a valid s32 range (due to matching sign bit),
          * try to learn from that
          */
         if ((s32)reg->u32_min_value <= (s32)reg->u32_max_value) {
                 reg->s32_min_value = max_t(s32, reg->s32_min_value, reg->u32_min_value);
                 reg->s32_max_value = min_t(s32, reg->s32_max_value, reg->u32_max_value);
         }
         /* If we cannot cross the sign boundary, then signed and unsigned bounds
          * are the same, so combine.  This works even in the negative case, e.g.
          * -3 s<= x s<= -1 implies 0xf...fd u<= x u<= 0xf...ff.
          */
         if ((u32)reg->s32_min_value <= (u32)reg->s32_max_value) {
                 reg->u32_min_value = max_t(u32, reg->s32_min_value, reg->u32_min_value);
                 reg->u32_max_value = min_t(u32, reg->s32_max_value, reg->u32_max_value);
         }
 }
 
 static void __reg64_deduce_bounds(struct bpf_reg_state *reg)
 {
         /* If u64 range forms a valid s64 range (due to matching sign bit),
          * try to learn from that. Let's do a bit of ASCII art to see when
          * this is happening. Let's take u64 range first:
          *
          * 0             0x7fffffffffffffff 0x8000000000000000        U64_MAX
          * |-------------------------------|--------------------------------|
          *
          * Valid u64 range is formed when umin and umax are anywhere in the
          * range [0, U64_MAX], and umin <= umax. u64 case is simple and
          * straightforward. Let's see how s64 range maps onto the same range
          * of values, annotated below the line for comparison:
          *
          * 0             0x7fffffffffffffff 0x8000000000000000        U64_MAX
          * |-------------------------------|--------------------------------|
          * 0                        S64_MAX S64_MIN                        -1
          *
          * So s64 values basically start in the middle and they are logically
          * contiguous to the right of it, wrapping around from -1 to 0, and
          * then finishing as S64_MAX (0x7fffffffffffffff) right before
          * S64_MIN. We can try drawing the continuity of u64 vs s64 values
          * more visually as mapped to sign-agnostic range of hex values.
          *
          *  u64 start                                               u64 end
          *  _______________________________________________________________
          * /                                                               \
          * 0             0x7fffffffffffffff 0x8000000000000000        U64_MAX
          * |-------------------------------|--------------------------------|
          * 0                        S64_MAX S64_MIN                        -1
          *                                / \
          * >------------------------------   ------------------------------->
          * s64 continues...        s64 end   s64 start          s64 "midpoint"
          *
          * What this means is that, in general, we can't always derive
          * something new about u64 from any random s64 range, and vice versa.
          *
          * But we can do that in two particular cases. One is when entire
          * u64/s64 range is *entirely* contained within left half of the above
          * diagram or when it is *entirely* contained in the right half. I.e.:
          *
          * |-------------------------------|--------------------------------|
          *     ^                   ^            ^                 ^
          *     A                   B            C                 D
          *
          * [A, B] and [C, D] are contained entirely in their respective halves
          * and form valid contiguous ranges as both u64 and s64 values. [A, B]
          * will be non-negative both as u64 and s64 (and in fact it will be
          * identical ranges no matter the signedness). [C, D] treated as s64
          * will be a range of negative values, while in u64 it will be
          * non-negative range of values larger than 0x8000000000000000.
          *
          * Now, any other range here can't be represented in both u64 and s64
          * simultaneously. E.g., [A, C], [A, D], [B, C], [B, D] are valid
          * contiguous u64 ranges, but they are discontinuous in s64. [B, C]
          * in s64 would be properly presented as [S64_MIN, C] and [B, S64_MAX],
          * for example. Similarly, valid s64 range [D, A] (going from negative
          * to positive values), would be two separate [D, U64_MAX] and [0, A]
          * ranges as u64. Currently reg_state can't represent two segments per
          * numeric domain, so in such situations we can only derive maximal
          * possible range ([0, U64_MAX] for u64, and [S64_MIN, S64_MAX] for s64).
          *
          * So we use these facts to derive umin/umax from smin/smax and vice
          * versa only if they stay within the same "half". This is equivalent
          * to checking sign bit: lower half will have sign bit as zero, upper
          * half have sign bit 1. Below in code we simplify this by just
          * casting umin/umax as smin/smax and checking if they form valid
          * range, and vice versa. Those are equivalent checks.
          */
         if ((s64)reg->umin_value <= (s64)reg->umax_value) {
                 reg->smin_value = max_t(s64, reg->smin_value, reg->umin_value);
                 reg->smax_value = min_t(s64, reg->smax_value, reg->umax_value);
         }
         /* If we cannot cross the sign boundary, then signed and unsigned bounds
          * are the same, so combine.  This works even in the negative case, e.g.
          * -3 s<= x s<= -1 implies 0xf...fd u<= x u<= 0xf...ff.
          */
         if ((u64)reg->smin_value <= (u64)reg->smax_value) {
                 reg->umin_value = max_t(u64, reg->smin_value, reg->umin_value);
                 reg->umax_value = min_t(u64, reg->smax_value, reg->umax_value);
         }
 }
 
 static void __reg_deduce_mixed_bounds(struct bpf_reg_state *reg)
 {
         /* Try to tighten 64-bit bounds from 32-bit knowledge, using 32-bit
          * values on both sides of 64-bit range in hope to have tighter range.
          * E.g., if r1 is [0x1'00000000, 0x3'80000000], and we learn from
          * 32-bit signed > 0 operation that s32 bounds are now [1; 0x7fffffff].
          * With this, we can substitute 1 as low 32-bits of _low_ 64-bit bound
          * (0x100000000 -> 0x100000001) and 0x7fffffff as low 32-bits of
          * _high_ 64-bit bound (0x380000000 -> 0x37fffffff) and arrive at a
          * better overall bounds for r1 as [0x1'000000001; 0x3'7fffffff].
          * We just need to make sure that derived bounds we are intersecting
          * with are well-formed ranges in respective s64 or u64 domain, just
          * like we do with similar kinds of 32-to-64 or 64-to-32 adjustments.
          */
         __u64 new_umin, new_umax;
         __s64 new_smin, new_smax;
 
         /* u32 -> u64 tightening, it's always well-formed */
         new_umin = (reg->umin_value & ~0xffffffffULL) | reg->u32_min_value;
         new_umax = (reg->umax_value & ~0xffffffffULL) | reg->u32_max_value;
         reg->umin_value = max_t(u64, reg->umin_value, new_umin);
         reg->umax_value = min_t(u64, reg->umax_value, new_umax);
         /* u32 -> s64 tightening, u32 range embedded into s64 preserves range validity */
         new_smin = (reg->smin_value & ~0xffffffffULL) | reg->u32_min_value;
         new_smax = (reg->smax_value & ~0xffffffffULL) | reg->u32_max_value;
         reg->smin_value = max_t(s64, reg->smin_value, new_smin);
         reg->smax_value = min_t(s64, reg->smax_value, new_smax);
 
         /* if s32 can be treated as valid u32 range, we can use it as well */
         if ((u32)reg->s32_min_value <= (u32)reg->s32_max_value) {
                 /* s32 -> u64 tightening */
                 new_umin = (reg->umin_value & ~0xffffffffULL) | (u32)reg->s32_min_value;
                 new_umax = (reg->umax_value & ~0xffffffffULL) | (u32)reg->s32_max_value;
                 reg->umin_value = max_t(u64, reg->umin_value, new_umin);
                 reg->umax_value = min_t(u64, reg->umax_value, new_umax);
                 /* s32 -> s64 tightening */
                 new_smin = (reg->smin_value & ~0xffffffffULL) | (u32)reg->s32_min_value;
                 new_smax = (reg->smax_value & ~0xffffffffULL) | (u32)reg->s32_max_value;
                 reg->smin_value = max_t(s64, reg->smin_value, new_smin);
                 reg->smax_value = min_t(s64, reg->smax_value, new_smax);
         }
 }
 
 static void __reg_deduce_bounds(struct bpf_reg_state *reg)
 {
         __reg32_deduce_bounds(reg);
         __reg64_deduce_bounds(reg);
         __reg_deduce_mixed_bounds(reg);
 }
 
 /* Attempts to improve var_off based on unsigned min/max information */
 static void __reg_bound_offset(struct bpf_reg_state *reg)
 {
         struct tnum var64_off = tnum_intersect(reg->var_off,
                                                tnum_range(reg->umin_value,
                                                           reg->umax_value));
         struct tnum var32_off = tnum_intersect(tnum_subreg(var64_off),
                                                tnum_range(reg->u32_min_value,
                                                           reg->u32_max_value));
 
         reg->var_off = tnum_or(tnum_clear_subreg(var64_off), var32_off);
 }
 
 static void reg_bounds_sync(struct bpf_reg_state *reg)
 {
         /* We might have learned new bounds from the var_off. */
         __update_reg_bounds(reg);
         /* We might have learned something about the sign bit. */
         __reg_deduce_bounds(reg);
         __reg_deduce_bounds(reg);
         /* We might have learned some bits from the bounds. */
         __reg_bound_offset(reg);
         /* Intersecting with the old var_off might have improved our bounds
          * slightly, e.g. if umax was 0x7f...f and var_off was (0; 0xf...fc),
          * then new var_off is (0; 0x7f...fc) which improves our umax.
          */
         __update_reg_bounds(reg);
 }
 
 static int reg_bounds_sanity_check(struct bpf_verifier_env *env,
                                    struct bpf_reg_state *reg, const char *ctx)
 {
         const char *msg;
 
         if (reg->umin_value > reg->umax_value ||
             reg->smin_value > reg->smax_value ||
             reg->u32_min_value > reg->u32_max_value ||
             reg->s32_min_value > reg->s32_max_value) {
                     msg = "range bounds violation";
                     goto out;
         }
 
         if (tnum_is_const(reg->var_off)) {
                 u64 uval = reg->var_off.value;
                 s64 sval = (s64)uval;
 
                 if (reg->umin_value != uval || reg->umax_value != uval ||
                     reg->smin_value != sval || reg->smax_value != sval) {
                         msg = "const tnum out of sync with range bounds";
                         goto out;
                 }
         }
 
         if (tnum_subreg_is_const(reg->var_off)) {
                 u32 uval32 = tnum_subreg(reg->var_off).value;
                 s32 sval32 = (s32)uval32;
 
                 if (reg->u32_min_value != uval32 || reg->u32_max_value != uval32 ||
                     reg->s32_min_value != sval32 || reg->s32_max_value != sval32) {
                         msg = "const subreg tnum out of sync with range bounds";
                         goto out;
                 }
         }
 
         return 0;
 out:
         verbose(env, "REG INVARIANTS VIOLATION (%s): %s u64=[%#llx, %#llx] "
                 "s64=[%#llx, %#llx] u32=[%#x, %#x] s32=[%#x, %#x] var_off=(%#llx, %#llx)\n",
                 ctx, msg, reg->umin_value, reg->umax_value,
                 reg->smin_value, reg->smax_value,
                 reg->u32_min_value, reg->u32_max_value,
                 reg->s32_min_value, reg->s32_max_value,
                 reg->var_off.value, reg->var_off.mask);
         if (env->test_reg_invariants)
                 return -EFAULT;
         __mark_reg_unbounded(reg);
         return 0;
 }
 
 static bool __reg32_bound_s64(s32 a)
 {
         return a >= 0 && a <= S32_MAX;
 }
 
 static void __reg_assign_32_into_64(struct bpf_reg_state *reg)
 {
         reg->umin_value = reg->u32_min_value;
         reg->umax_value = reg->u32_max_value;
 
         /* Attempt to pull 32-bit signed bounds into 64-bit bounds but must
          * be positive otherwise set to worse case bounds and refine later
          * from tnum.
          */
         if (__reg32_bound_s64(reg->s32_min_value) &&
             __reg32_bound_s64(reg->s32_max_value)) {
                 reg->smin_value = reg->s32_min_value;
                 reg->smax_value = reg->s32_max_value;
         } else {
                 reg->smin_value = 0;
                 reg->smax_value = U32_MAX;
         }
 }
 
 /* Mark a register as having a completely unknown (scalar) value. */
 static void __mark_reg_unknown_imprecise(struct bpf_reg_state *reg)
 {
         /*
          * Clear type, off, and union(map_ptr, range) and
          * padding between 'type' and union
          */
         memset(reg, 0, offsetof(struct bpf_reg_state, var_off));
         reg->type = SCALAR_VALUE;
         reg->id = 0;
         reg->ref_obj_id = 0;
         reg->var_off = tnum_unknown;
         reg->frameno = 0;
         reg->precise = false;
         __mark_reg_unbounded(reg);
 }
 
 /* Mark a register as having a completely unknown (scalar) value,
  * initialize .precise as true when not bpf capable.
  */
 static void __mark_reg_unknown(const struct bpf_verifier_env *env,
                                struct bpf_reg_state *reg)
 {
         __mark_reg_unknown_imprecise(reg);
         reg->precise = !env->bpf_capable;
 }
 
 static void mark_reg_unknown(struct bpf_verifier_env *env,
                              struct bpf_reg_state *regs, u32 regno)
 {
         if (WARN_ON(regno >= MAX_BPF_REG)) {
                 verbose(env, "mark_reg_unknown(regs, %u)\n", regno);
                 /* Something bad happened, let's kill all regs except FP */
                 for (regno = 0; regno < BPF_REG_FP; regno++)
                         __mark_reg_not_init(env, regs + regno);
                 return;
         }
         __mark_reg_unknown(env, regs + regno);
 }
 
 static int __mark_reg_s32_range(struct bpf_verifier_env *env,
                                 struct bpf_reg_state *regs,
                                 u32 regno,
                                 s32 s32_min,
                                 s32 s32_max)
 {
         struct bpf_reg_state *reg = regs + regno;
 
         reg->s32_min_value = max_t(s32, reg->s32_min_value, s32_min);
         reg->s32_max_value = min_t(s32, reg->s32_max_value, s32_max);
 
         reg->smin_value = max_t(s64, reg->smin_value, s32_min);
         reg->smax_value = min_t(s64, reg->smax_value, s32_max);
 
         reg_bounds_sync(reg);
 
         return reg_bounds_sanity_check(env, reg, "s32_range");
 }
 
 static void __mark_reg_not_init(const struct bpf_verifier_env *env,
                                 struct bpf_reg_state *reg)
 {
         __mark_reg_unknown(env, reg);
         reg->type = NOT_INIT;
 }
 
 static void mark_reg_not_init(struct bpf_verifier_env *env,
                               struct bpf_reg_state *regs, u32 regno)
 {
         if (WARN_ON(regno >= MAX_BPF_REG)) {
                 verbose(env, "mark_reg_not_init(regs, %u)\n", regno);
                 /* Something bad happened, let's kill all regs except FP */
                 for (regno = 0; regno < BPF_REG_FP; regno++)
                         __mark_reg_not_init(env, regs + regno);
                 return;
         }
         __mark_reg_not_init(env, regs + regno);
 }
 
 static void mark_btf_ld_reg(struct bpf_verifier_env *env,
                             struct bpf_reg_state *regs, u32 regno,
                             enum bpf_reg_type reg_type,
                             struct btf *btf, u32 btf_id,
                             enum bpf_type_flag flag)
 {
         if (reg_type == SCALAR_VALUE) {
                 mark_reg_unknown(env, regs, regno);
                 return;
         }
         mark_reg_known_zero(env, regs, regno);
         regs[regno].type = PTR_TO_BTF_ID | flag;
         regs[regno].btf = btf;
         regs[regno].btf_id = btf_id;
         if (type_may_be_null(flag))
                 regs[regno].id = ++env->id_gen;
 }
 
 #define DEF_NOT_SUBREG  (0)
 static void init_reg_state(struct bpf_verifier_env *env,
                            struct bpf_func_state *state)
 {
         struct bpf_reg_state *regs = state->regs;
         int i;
 
         for (i = 0; i < MAX_BPF_REG; i++) {
                 mark_reg_not_init(env, regs, i);
                 regs[i].live = REG_LIVE_NONE;
                 regs[i].parent = NULL;
                 regs[i].subreg_def = DEF_NOT_SUBREG;
         }
 
         /* frame pointer */
         regs[BPF_REG_FP].type = PTR_TO_STACK;
         mark_reg_known_zero(env, regs, BPF_REG_FP);
         regs[BPF_REG_FP].frameno = state->frameno;
 }
 
 static struct bpf_retval_range retval_range(s32 minval, s32 maxval)
 {
         return (struct bpf_retval_range){ minval, maxval };
 }
 
 #define BPF_MAIN_FUNC (-1)
 static void init_func_state(struct bpf_verifier_env *env,
                             struct bpf_func_state *state,
                             int callsite, int frameno, int subprogno)
 {
         state->callsite = callsite;
         state->frameno = frameno;
         state->subprogno = subprogno;
         state->callback_ret_range = retval_range(0, 0);
         init_reg_state(env, state);
         mark_verifier_state_scratched(env);
 }
 
 /* Similar to push_stack(), but for async callbacks */
 static struct bpf_verifier_state *push_async_cb(struct bpf_verifier_env *env,
                                                 int insn_idx, int prev_insn_idx,
                                                 int subprog, bool is_sleepable)
 {
         struct bpf_verifier_stack_elem *elem;
         struct bpf_func_state *frame;
 
         elem = kzalloc(sizeof(struct bpf_verifier_stack_elem), GFP_KERNEL);
         if (!elem)
                 goto err;
 
         elem->insn_idx = insn_idx;
         elem->prev_insn_idx = prev_insn_idx;
         elem->next = env->head;
         elem->log_pos = env->log.end_pos;
         env->head = elem;
         env->stack_size++;
         if (env->stack_size > BPF_COMPLEXITY_LIMIT_JMP_SEQ) {
                 verbose(env,
                         "The sequence of %d jumps is too complex for async cb.\n",
                         env->stack_size);
                 goto err;
         }
         /* Unlike push_stack() do not copy_verifier_state().
          * The caller state doesn't matter.
          * This is async callback. It starts in a fresh stack.
          * Initialize it similar to do_check_common().
          */
         elem->st.branches = 1;
         elem->st.in_sleepable = is_sleepable;
         frame = kzalloc(sizeof(*frame), GFP_KERNEL);
         if (!frame)
                 goto err;
         init_func_state(env, frame,
                         BPF_MAIN_FUNC /* callsite */,
                         0 /* frameno within this callchain */,
                         subprog /* subprog number within this prog */);
         elem->st.frame[0] = frame;
         return &elem->st;
 err:
         free_verifier_state(env->cur_state, true);
         env->cur_state = NULL;
         /* pop all elements and return */
         while (!pop_stack(env, NULL, NULL, false));
         return NULL;
 }
 
 
 enum reg_arg_type {
         SRC_OP,         /* register is used as source operand */
         DST_OP,         /* register is used as destination operand */
         DST_OP_NO_MARK  /* same as above, check only, don't mark */
 };
 
 static int cmp_subprogs(const void *a, const void *b)
 {
         return ((struct bpf_subprog_info *)a)->start -
                ((struct bpf_subprog_info *)b)->start;
 }
 
 static int find_subprog(struct bpf_verifier_env *env, int off)
 {
         struct bpf_subprog_info *p;
 
         p = bsearch(&off, env->subprog_info, env->subprog_cnt,
                     sizeof(env->subprog_info[0]), cmp_subprogs);
         if (!p)
                 return -ENOENT;
         return p - env->subprog_info;
 
 }
 
 static int add_subprog(struct bpf_verifier_env *env, int off)
 {
         int insn_cnt = env->prog->len;
         int ret;
 
         if (off >= insn_cnt || off < 0) {
                 verbose(env, "call to invalid destination\n");
                 return -EINVAL;
         }
         ret = find_subprog(env, off);
         if (ret >= 0)
                 return ret;
         if (env->subprog_cnt >= BPF_MAX_SUBPROGS) {
                 verbose(env, "too many subprograms\n");
                 return -E2BIG;
         }
         /* determine subprog starts. The end is one before the next starts */
         env->subprog_info[env->subprog_cnt++].start = off;
         sort(env->subprog_info, env->subprog_cnt,
              sizeof(env->subprog_info[0]), cmp_subprogs, NULL);
         return env->subprog_cnt - 1;
 }
 
 static int bpf_find_exception_callback_insn_off(struct bpf_verifier_env *env)
 {
         struct bpf_prog_aux *aux = env->prog->aux;
         struct btf *btf = aux->btf;
         const struct btf_type *t;
         u32 main_btf_id, id;
         const char *name;
         int ret, i;
 
         /* Non-zero func_info_cnt implies valid btf */
         if (!aux->func_info_cnt)
                 return 0;
         main_btf_id = aux->func_info[0].type_id;
 
         t = btf_type_by_id(btf, main_btf_id);
         if (!t) {
                 verbose(env, "invalid btf id for main subprog in func_info\n");
                 return -EINVAL;
         }
 
         name = btf_find_decl_tag_value(btf, t, -1, "exception_callback:");
         if (IS_ERR(name)) {
                 ret = PTR_ERR(name);
                 /* If there is no tag present, there is no exception callback */
                 if (ret == -ENOENT)
                         ret = 0;
                 else if (ret == -EEXIST)
                         verbose(env, "multiple exception callback tags for main subprog\n");
                 return ret;
         }
 
         ret = btf_find_by_name_kind(btf, name, BTF_KIND_FUNC);
         if (ret < 0) {
                 verbose(env, "exception callback '%s' could not be found in BTF\n", name);
                 return ret;
         }
         id = ret;
         t = btf_type_by_id(btf, id);
         if (btf_func_linkage(t) != BTF_FUNC_GLOBAL) {
                 verbose(env, "exception callback '%s' must have global linkage\n", name);
                 return -EINVAL;
         }
         ret = 0;
         for (i = 0; i < aux->func_info_cnt; i++) {
                 if (aux->func_info[i].type_id != id)
                         continue;
                 ret = aux->func_info[i].insn_off;
                 /* Further func_info and subprog checks will also happen
                  * later, so assume this is the right insn_off for now.
                  */
                 if (!ret) {
                         verbose(env, "invalid exception callback insn_off in func_info: 0\n");
                         ret = -EINVAL;
                 }
         }
         if (!ret) {
                 verbose(env, "exception callback type id not found in func_info\n");
                 ret = -EINVAL;
         }
         return ret;
 }
 
 #define MAX_KFUNC_DESCS 256
 #define MAX_KFUNC_BTFS  256
 
 struct bpf_kfunc_desc {
         struct btf_func_model func_model;
         u32 func_id;
         s32 imm;
         u16 offset;
         unsigned long addr;
 };
 
 struct bpf_kfunc_btf {
         struct btf *btf;
         struct module *module;
         u16 offset;
 };
 
 struct bpf_kfunc_desc_tab {
         /* Sorted by func_id (BTF ID) and offset (fd_array offset) during
          * verification. JITs do lookups by bpf_insn, where func_id may not be
          * available, therefore at the end of verification do_misc_fixups()
          * sorts this by imm and offset.
          */
         struct bpf_kfunc_desc descs[MAX_KFUNC_DESCS];
         u32 nr_descs;
 };
 
 struct bpf_kfunc_btf_tab {
         struct bpf_kfunc_btf descs[MAX_KFUNC_BTFS];
         u32 nr_descs;
 };
 
 static int kfunc_desc_cmp_by_id_off(const void *a, const void *b)
 {
         const struct bpf_kfunc_desc *d0 = a;
         const struct bpf_kfunc_desc *d1 = b;
 
         /* func_id is not greater than BTF_MAX_TYPE */
         return d0->func_id - d1->func_id ?: d0->offset - d1->offset;
 }
 
 static int kfunc_btf_cmp_by_off(const void *a, const void *b)
 {
         const struct bpf_kfunc_btf *d0 = a;
         const struct bpf_kfunc_btf *d1 = b;
 
         return d0->offset - d1->offset;
 }
 
 static const struct bpf_kfunc_desc *
 find_kfunc_desc(const struct bpf_prog *prog, u32 func_id, u16 offset)
 {
         struct bpf_kfunc_desc desc = {
                 .func_id = func_id,
                 .offset = offset,
         };
         struct bpf_kfunc_desc_tab *tab;
 
         tab = prog->aux->kfunc_tab;
         return bsearch(&desc, tab->descs, tab->nr_descs,
                        sizeof(tab->descs[0]), kfunc_desc_cmp_by_id_off);
 }
 
 int bpf_get_kfunc_addr(const struct bpf_prog *prog, u32 func_id,
                        u16 btf_fd_idx, u8 **func_addr)
 {
         const struct bpf_kfunc_desc *desc;
 
         desc = find_kfunc_desc(prog, func_id, btf_fd_idx);
         if (!desc)
                 return -EFAULT;
 
         *func_addr = (u8 *)desc->addr;
         return 0;
 }
 
 static struct btf *__find_kfunc_desc_btf(struct bpf_verifier_env *env,
                                          s16 offset)
 {
         struct bpf_kfunc_btf kf_btf = { .offset = offset };
         struct bpf_kfunc_btf_tab *tab;
         struct bpf_kfunc_btf *b;
         struct module *mod;
         struct btf *btf;
         int btf_fd;
 
         tab = env->prog->aux->kfunc_btf_tab;
         b = bsearch(&kf_btf, tab->descs, tab->nr_descs,
                     sizeof(tab->descs[0]), kfunc_btf_cmp_by_off);
         if (!b) {
                 if (tab->nr_descs == MAX_KFUNC_BTFS) {
                         verbose(env, "too many different module BTFs\n");
                         return ERR_PTR(-E2BIG);
                 }
 
                 if (bpfptr_is_null(env->fd_array)) {
                         verbose(env, "kfunc offset > 0 without fd_array is invalid\n");
                         return ERR_PTR(-EPROTO);
                 }
 
                 if (copy_from_bpfptr_offset(&btf_fd, env->fd_array,
                                             offset * sizeof(btf_fd),
                                             sizeof(btf_fd)))
                         return ERR_PTR(-EFAULT);
 
                 btf = btf_get_by_fd(btf_fd);
                 if (IS_ERR(btf)) {
                         verbose(env, "invalid module BTF fd specified\n");
                         return btf;
                 }
 
                 if (!btf_is_module(btf)) {
                         verbose(env, "BTF fd for kfunc is not a module BTF\n");
                         btf_put(btf);
                         return ERR_PTR(-EINVAL);
                 }
 
                 mod = btf_try_get_module(btf);
                 if (!mod) {
                         btf_put(btf);
                         return ERR_PTR(-ENXIO);
                 }
 
                 b = &tab->descs[tab->nr_descs++];
                 b->btf = btf;
                 b->module = mod;
                 b->offset = offset;
 
                 sort(tab->descs, tab->nr_descs, sizeof(tab->descs[0]),
                      kfunc_btf_cmp_by_off, NULL);
         }
         return b->btf;
 }
 
 void bpf_free_kfunc_btf_tab(struct bpf_kfunc_btf_tab *tab)
 {
         if (!tab)
                 return;
 
         while (tab->nr_descs--) {
                 module_put(tab->descs[tab->nr_descs].module);
                 btf_put(tab->descs[tab->nr_descs].btf);
         }
         kfree(tab);
 }
 
 static struct btf *find_kfunc_desc_btf(struct bpf_verifier_env *env, s16 offset)
 {
         if (offset) {
                 if (offset < 0) {
                         /* In the future, this can be allowed to increase limit
                          * of fd index into fd_array, interpreted as u16.
                          */
                         verbose(env, "negative offset disallowed for kernel module function call\n");
                         return ERR_PTR(-EINVAL);
                 }
 
                 return __find_kfunc_desc_btf(env, offset);
         }
         return btf_vmlinux ?: ERR_PTR(-ENOENT);
 }
 
 static int add_kfunc_call(struct bpf_verifier_env *env, u32 func_id, s16 offset)
 {
         const struct btf_type *func, *func_proto;
         struct bpf_kfunc_btf_tab *btf_tab;
         struct bpf_kfunc_desc_tab *tab;
         struct bpf_prog_aux *prog_aux;
         struct bpf_kfunc_desc *desc;
         const char *func_name;
         struct btf *desc_btf;
         unsigned long call_imm;
         unsigned long addr;
         int err;
 
         prog_aux = env->prog->aux;
         tab = prog_aux->kfunc_tab;
         btf_tab = prog_aux->kfunc_btf_tab;
         if (!tab) {
                 if (!btf_vmlinux) {
                         verbose(env, "calling kernel function is not supported without CONFIG_DEBUG_INFO_BTF\n");
                         return -ENOTSUPP;
                 }
 
                 if (!env->prog->jit_requested) {
                         verbose(env, "JIT is required for calling kernel function\n");
                         return -ENOTSUPP;
                 }
 
                 if (!bpf_jit_supports_kfunc_call()) {
                         verbose(env, "JIT does not support calling kernel function\n");
                         return -ENOTSUPP;
                 }
 
                 if (!env->prog->gpl_compatible) {
                         verbose(env, "cannot call kernel function from non-GPL compatible program\n");
                         return -EINVAL;
                 }
 
                 tab = kzalloc(sizeof(*tab), GFP_KERNEL);
                 if (!tab)
                         return -ENOMEM;
                 prog_aux->kfunc_tab = tab;
         }
 
         /* func_id == 0 is always invalid, but instead of returning an error, be
          * conservative and wait until the code elimination pass before returning
          * error, so that invalid calls that get pruned out can be in BPF programs
          * loaded from userspace.  It is also required that offset be untouched
          * for such calls.
          */
         if (!func_id && !offset)
                 return 0;
 
         if (!btf_tab && offset) {
                 btf_tab = kzalloc(sizeof(*btf_tab), GFP_KERNEL);
                 if (!btf_tab)
                         return -ENOMEM;
                 prog_aux->kfunc_btf_tab = btf_tab;
         }
 
         desc_btf = find_kfunc_desc_btf(env, offset);
         if (IS_ERR(desc_btf)) {
                 verbose(env, "failed to find BTF for kernel function\n");
                 return PTR_ERR(desc_btf);
         }
 
         if (find_kfunc_desc(env->prog, func_id, offset))
                 return 0;
 
         if (tab->nr_descs == MAX_KFUNC_DESCS) {
                 verbose(env, "too many different kernel function calls\n");
                 return -E2BIG;
         }
 
         func = btf_type_by_id(desc_btf, func_id);
         if (!func || !btf_type_is_func(func)) {
                 verbose(env, "kernel btf_id %u is not a function\n",
                         func_id);
                 return -EINVAL;
         }
         func_proto = btf_type_by_id(desc_btf, func->type);
         if (!func_proto || !btf_type_is_func_proto(func_proto)) {
                 verbose(env, "kernel function btf_id %u does not have a valid func_proto\n",
                         func_id);
                 return -EINVAL;
         }
 
         func_name = btf_name_by_offset(desc_btf, func->name_off);
         addr = kallsyms_lookup_name(func_name);
         if (!addr) {
                 verbose(env, "cannot find address for kernel function %s\n",
                         func_name);
                 return -EINVAL;
         }
         specialize_kfunc(env, func_id, offset, &addr);
 
         if (bpf_jit_supports_far_kfunc_call()) {
                 call_imm = func_id;
         } else {
                 call_imm = BPF_CALL_IMM(addr);
                 /* Check whether the relative offset overflows desc->imm */
                 if ((unsigned long)(s32)call_imm != call_imm) {
                         verbose(env, "address of kernel function %s is out of range\n",
                                 func_name);
                         return -EINVAL;
                 }
         }
 
         if (bpf_dev_bound_kfunc_id(func_id)) {
                 err = bpf_dev_bound_kfunc_check(&env->log, prog_aux);
                 if (err)
                         return err;
         }
 
         desc = &tab->descs[tab->nr_descs++];
         desc->func_id = func_id;
         desc->imm = call_imm;
         desc->offset = offset;
         desc->addr = addr;
         err = btf_distill_func_proto(&env->log, desc_btf,
                                      func_proto, func_name,
                                      &desc->func_model);
         if (!err)
                 sort(tab->descs, tab->nr_descs, sizeof(tab->descs[0]),
                      kfunc_desc_cmp_by_id_off, NULL);
         return err;
 }
 
 static int kfunc_desc_cmp_by_imm_off(const void *a, const void *b)
 {
         const struct bpf_kfunc_desc *d0 = a;
         const struct bpf_kfunc_desc *d1 = b;
 
         if (d0->imm != d1->imm)
                 return d0->imm < d1->imm ? -1 : 1;
         if (d0->offset != d1->offset)
                 return d0->offset < d1->offset ? -1 : 1;
         return 0;
 }
 
 static void sort_kfunc_descs_by_imm_off(struct bpf_prog *prog)
 {
         struct bpf_kfunc_desc_tab *tab;
 
         tab = prog->aux->kfunc_tab;
         if (!tab)
                 return;
 
         sort(tab->descs, tab->nr_descs, sizeof(tab->descs[0]),
              kfunc_desc_cmp_by_imm_off, NULL);
 }
 
 bool bpf_prog_has_kfunc_call(const struct bpf_prog *prog)
 {
         return !!prog->aux->kfunc_tab;
 }
 
 const struct btf_func_model *
 bpf_jit_find_kfunc_model(const struct bpf_prog *prog,
                          const struct bpf_insn *insn)
 {
         const struct bpf_kfunc_desc desc = {
                 .imm = insn->imm,
                 .offset = insn->off,
         };
         const struct bpf_kfunc_desc *res;
         struct bpf_kfunc_desc_tab *tab;
 
         tab = prog->aux->kfunc_tab;
         res = bsearch(&desc, tab->descs, tab->nr_descs,
                       sizeof(tab->descs[0]), kfunc_desc_cmp_by_imm_off);
 
         return res ? &res->func_model : NULL;
 }
 
 static int add_subprog_and_kfunc(struct bpf_verifier_env *env)
 {
         struct bpf_subprog_info *subprog = env->subprog_info;
         int i, ret, insn_cnt = env->prog->len, ex_cb_insn;
         struct bpf_insn *insn = env->prog->insnsi;
 
         /* Add entry function. */
         ret = add_subprog(env, 0);
         if (ret)
                 return ret;
 
         for (i = 0; i < insn_cnt; i++, insn++) {
                 if (!bpf_pseudo_func(insn) && !bpf_pseudo_call(insn) &&
                     !bpf_pseudo_kfunc_call(insn))
                         continue;
 
                 if (!env->bpf_capable) {
                         verbose(env, "loading/calling other bpf or kernel functions are allowed for CAP_BPF and CAP_SYS_ADMIN\n");
                         return -EPERM;
                 }
 
                 if (bpf_pseudo_func(insn) || bpf_pseudo_call(insn))
                         ret = add_subprog(env, i + insn->imm + 1);
                 else
                         ret = add_kfunc_call(env, insn->imm, insn->off);
 
                 if (ret < 0)
                         return ret;
         }
 
         ret = bpf_find_exception_callback_insn_off(env);
         if (ret < 0)
                 return ret;
         ex_cb_insn = ret;
 
         /* If ex_cb_insn > 0, this means that the main program has a subprog
          * marked using BTF decl tag to serve as the exception callback.
          */
         if (ex_cb_insn) {
                 ret = add_subprog(env, ex_cb_insn);
                 if (ret < 0)
                         return ret;
                 for (i = 1; i < env->subprog_cnt; i++) {
                         if (env->subprog_info[i].start != ex_cb_insn)
                                 continue;
                         env->exception_callback_subprog = i;
                         mark_subprog_exc_cb(env, i);
                         break;
                 }
         }
 
         /* Add a fake 'exit' subprog which could simplify subprog iteration
          * logic. 'subprog_cnt' should not be increased.
          */
         subprog[env->subprog_cnt].start = insn_cnt;
 
         if (env->log.level & BPF_LOG_LEVEL2)
                 for (i = 0; i < env->subprog_cnt; i++)
                         verbose(env, "func#%d @%d\n", i, subprog[i].start);
 
         return 0;
 }
 
 static int check_subprogs(struct bpf_verifier_env *env)
 {
         int i, subprog_start, subprog_end, off, cur_subprog = 0;
         struct bpf_subprog_info *subprog = env->subprog_info;
         struct bpf_insn *insn = env->prog->insnsi;
         int insn_cnt = env->prog->len;
 
         /* now check that all jumps are within the same subprog */
         subprog_start = subprog[cur_subprog].start;
         subprog_end = subprog[cur_subprog + 1].start;
         for (i = 0; i < insn_cnt; i++) {
                 u8 code = insn[i].code;
 
                 if (code == (BPF_JMP | BPF_CALL) &&
                     insn[i].src_reg == 0 &&
                     insn[i].imm == BPF_FUNC_tail_call) {
                         subprog[cur_subprog].has_tail_call = true;
                         subprog[cur_subprog].tail_call_reachable = true;
                 }
                 if (BPF_CLASS(code) == BPF_LD &&
                     (BPF_MODE(code) == BPF_ABS || BPF_MODE(code) == BPF_IND))
                         subprog[cur_subprog].has_ld_abs = true;
                 if (BPF_CLASS(code) != BPF_JMP && BPF_CLASS(code) != BPF_JMP32)
                         goto next;
                 if (BPF_OP(code) == BPF_EXIT || BPF_OP(code) == BPF_CALL)
                         goto next;
                 if (code == (BPF_JMP32 | BPF_JA))
                         off = i + insn[i].imm + 1;
                 else
                         off = i + insn[i].off + 1;
                 if (off < subprog_start || off >= subprog_end) {
                         verbose(env, "jump out of range from insn %d to %d\n", i, off);
                         return -EINVAL;
                 }
 next:
                 if (i == subprog_end - 1) {
                         /* to avoid fall-through from one subprog into another
                          * the last insn of the subprog should be either exit
                          * or unconditional jump back or bpf_throw call
                          */
                         if (code != (BPF_JMP | BPF_EXIT) &&
                             code != (BPF_JMP32 | BPF_JA) &&
                             code != (BPF_JMP | BPF_JA)) {
                                 verbose(env, "last insn is not an exit or jmp\n");
                                 return -EINVAL;
                         }
                         subprog_start = subprog_end;
                         cur_subprog++;
                         if (cur_subprog < env->subprog_cnt)
                                 subprog_end = subprog[cur_subprog + 1].start;
                 }
         }
         return 0;
 }
 
 /* Parentage chain of this register (or stack slot) should take care of all
  * issues like callee-saved registers, stack slot allocation time, etc.
  */
 static int mark_reg_read(struct bpf_verifier_env *env,
                          const struct bpf_reg_state *state,
                          struct bpf_reg_state *parent, u8 flag)
 {
         bool writes = parent == state->parent; /* Observe write marks */
         int cnt = 0;
 
         while (parent) {
                 /* if read wasn't screened by an earlier write ... */
                 if (writes && state->live & REG_LIVE_WRITTEN)
                         break;
                 if (parent->live & REG_LIVE_DONE) {
                         verbose(env, "verifier BUG type %s var_off %lld off %d\n",
                                 reg_type_str(env, parent->type),
                                 parent->var_off.value, parent->off);
                         return -EFAULT;
                 }
                 /* The first condition is more likely to be true than the
                  * second, checked it first.
                  */
                 if ((parent->live & REG_LIVE_READ) == flag ||
                     parent->live & REG_LIVE_READ64)
                         /* The parentage chain never changes and
                          * this parent was already marked as LIVE_READ.
                          * There is no need to keep walking the chain again and
                          * keep re-marking all parents as LIVE_READ.
                          * This case happens when the same register is read
                          * multiple times without writes into it in-between.
                          * Also, if parent has the stronger REG_LIVE_READ64 set,
                          * then no need to set the weak REG_LIVE_READ32.
                          */
                         break;
                 /* ... then we depend on parent's value */
                 parent->live |= flag;
                 /* REG_LIVE_READ64 overrides REG_LIVE_READ32. */
                 if (flag == REG_LIVE_READ64)
                         parent->live &= ~REG_LIVE_READ32;
                 state = parent;
                 parent = state->parent;
                 writes = true;
                 cnt++;
         }
 
         if (env->longest_mark_read_walk < cnt)
                 env->longest_mark_read_walk = cnt;
         return 0;
 }
 
 static int mark_dynptr_read(struct bpf_verifier_env *env, struct bpf_reg_state *reg)
 {
         struct bpf_func_state *state = func(env, reg);
         int spi, ret;
 
         /* For CONST_PTR_TO_DYNPTR, it must have already been done by
          * check_reg_arg in check_helper_call and mark_btf_func_reg_size in
          * check_kfunc_call.
          */
         if (reg->type == CONST_PTR_TO_DYNPTR)
                 return 0;
         spi = dynptr_get_spi(env, reg);
         if (spi < 0)
                 return spi;
         /* Caller ensures dynptr is valid and initialized, which means spi is in
          * bounds and spi is the first dynptr slot. Simply mark stack slot as
          * read.
          */
         ret = mark_reg_read(env, &state->stack[spi].spilled_ptr,
                             state->stack[spi].spilled_ptr.parent, REG_LIVE_READ64);
         if (ret)
                 return ret;
         return mark_reg_read(env, &state->stack[spi - 1].spilled_ptr,
                              state->stack[spi - 1].spilled_ptr.parent, REG_LIVE_READ64);
 }
 
 static int mark_iter_read(struct bpf_verifier_env *env, struct bpf_reg_state *reg,
                           int spi, int nr_slots)
 {
         struct bpf_func_state *state = func(env, reg);
         int err, i;
 
         for (i = 0; i < nr_slots; i++) {
                 struct bpf_reg_state *st = &state->stack[spi - i].spilled_ptr;
 
                 err = mark_reg_read(env, st, st->parent, REG_LIVE_READ64);
                 if (err)
                         return err;
 
                 mark_stack_slot_scratched(env, spi - i);
         }
 
         return 0;
 }
 
 /* This function is supposed to be used by the following 32-bit optimization
  * code only. It returns TRUE if the source or destination register operates
  * on 64-bit, otherwise return FALSE.
  */
 static bool is_reg64(struct bpf_verifier_env *env, struct bpf_insn *insn,
                      u32 regno, struct bpf_reg_state *reg, enum reg_arg_type t)
 {
         u8 code, class, op;
 
         code = insn->code;
         class = BPF_CLASS(code);
         op = BPF_OP(code);
         if (class == BPF_JMP) {
                 /* BPF_EXIT for "main" will reach here. Return TRUE
                  * conservatively.
                  */
                 if (op == BPF_EXIT)
                         return true;
                 if (op == BPF_CALL) {
                         /* BPF to BPF call will reach here because of marking
                          * caller saved clobber with DST_OP_NO_MARK for which we
                          * don't care the register def because they are anyway
                          * marked as NOT_INIT already.
                          */
                         if (insn->src_reg == BPF_PSEUDO_CALL)
                                 return false;
                         /* Helper call will reach here because of arg type
                          * check, conservatively return TRUE.
                          */
                         if (t == SRC_OP)
                                 return true;
 
                         return false;
                 }
         }
 
         if (class == BPF_ALU64 && op == BPF_END && (insn->imm == 16 || insn->imm == 32))
                 return false;
 
         if (class == BPF_ALU64 || class == BPF_JMP ||
             (class == BPF_ALU && op == BPF_END && insn->imm == 64))
                 return true;
 
         if (class == BPF_ALU || class == BPF_JMP32)
                 return false;
 
         if (class == BPF_LDX) {
                 if (t != SRC_OP)
                         return BPF_SIZE(code) == BPF_DW || BPF_MODE(code) == BPF_MEMSX;
                 /* LDX source must be ptr. */
                 return true;
         }
 
         if (class == BPF_STX) {
                 /* BPF_STX (including atomic variants) has multiple source
                  * operands, one of which is a ptr. Check whether the caller is
                  * asking about it.
                  */
                 if (t == SRC_OP && reg->type != SCALAR_VALUE)
                         return true;
                 return BPF_SIZE(code) == BPF_DW;
         }
 
         if (class == BPF_LD) {
                 u8 mode = BPF_MODE(code);
 
                 /* LD_IMM64 */
                 if (mode == BPF_IMM)
                         return true;
 
                 /* Both LD_IND and LD_ABS return 32-bit data. */
                 if (t != SRC_OP)
                         return  false;
 
                 /* Implicit ctx ptr. */
                 if (regno == BPF_REG_6)
                         return true;
 
                 /* Explicit source could be any width. */
                 return true;
         }
 
         if (class == BPF_ST)
                 /* The only source register for BPF_ST is a ptr. */
                 return true;
 
         /* Conservatively return true at default. */
         return true;
 }
 
 /* Return the regno defined by the insn, or -1. */
 static int insn_def_regno(const struct bpf_insn *insn)
 {
         switch (BPF_CLASS(insn->code)) {
         case BPF_JMP:
         case BPF_JMP32:
         case BPF_ST:
                 return -1;
         case BPF_STX:
                 if ((BPF_MODE(insn->code) == BPF_ATOMIC ||
                      BPF_MODE(insn->code) == BPF_PROBE_ATOMIC) &&
                     (insn->imm & BPF_FETCH)) {
                         if (insn->imm == BPF_CMPXCHG)
                                 return BPF_REG_0;
                         else
                                 return insn->src_reg;
                 } else {
                         return -1;
                 }
         default:
                 return insn->dst_reg;
         }
 }
 
 /* Return TRUE if INSN has defined any 32-bit value explicitly. */
 static bool insn_has_def32(struct bpf_verifier_env *env, struct bpf_insn *insn)
 {
         int dst_reg = insn_def_regno(insn);
 
         if (dst_reg == -1)
                 return false;
 
         return !is_reg64(env, insn, dst_reg, NULL, DST_OP);
 }
 
 static void mark_insn_zext(struct bpf_verifier_env *env,
                            struct bpf_reg_state *reg)
 {
         s32 def_idx = reg->subreg_def;
 
         if (def_idx == DEF_NOT_SUBREG)
                 return;
 
         env->insn_aux_data[def_idx - 1].zext_dst = true;
         /* The dst will be zero extended, so won't be sub-register anymore. */
         reg->subreg_def = DEF_NOT_SUBREG;
 }
 
 static int __check_reg_arg(struct bpf_verifier_env *env, struct bpf_reg_state *regs, u32 regno,
                            enum reg_arg_type t)
 {
         struct bpf_insn *insn = env->prog->insnsi + env->insn_idx;
         struct bpf_reg_state *reg;
         bool rw64;
 
         if (regno >= MAX_BPF_REG) {
                 verbose(env, "R%d is invalid\n", regno);
                 return -EINVAL;
         }
 
         mark_reg_scratched(env, regno);
 
         reg = &regs[regno];
         rw64 = is_reg64(env, insn, regno, reg, t);
         if (t == SRC_OP) {
                 /* check whether register used as source operand can be read */
                 if (reg->type == NOT_INIT) {
                         verbose(env, "R%d !read_ok\n", regno);
                         return -EACCES;
                 }
                 /* We don't need to worry about FP liveness because it's read-only */
                 if (regno == BPF_REG_FP)
                         return 0;
 
                 if (rw64)
                         mark_insn_zext(env, reg);
 
                 return mark_reg_read(env, reg, reg->parent,
                                      rw64 ? REG_LIVE_READ64 : REG_LIVE_READ32);
         } else {
                 /* check whether register used as dest operand can be written to */
                 if (regno == BPF_REG_FP) {
                         verbose(env, "frame pointer is read only\n");
                         return -EACCES;
                 }
                 reg->live |= REG_LIVE_WRITTEN;
                 reg->subreg_def = rw64 ? DEF_NOT_SUBREG : env->insn_idx + 1;
                 if (t == DST_OP)
                         mark_reg_unknown(env, regs, regno);
         }
         return 0;
 }
 
 static int check_reg_arg(struct bpf_verifier_env *env, u32 regno,
                          enum reg_arg_type t)
 {
         struct bpf_verifier_state *vstate = env->cur_state;
         struct bpf_func_state *state = vstate->frame[vstate->curframe];
 
         return __check_reg_arg(env, state->regs, regno, t);
 }
 
 static int insn_stack_access_flags(int frameno, int spi)
 {
         return INSN_F_STACK_ACCESS | (spi << INSN_F_SPI_SHIFT) | frameno;
 }
 
 static int insn_stack_access_spi(int insn_flags)
 {
         return (insn_flags >> INSN_F_SPI_SHIFT) & INSN_F_SPI_MASK;
 }
 
 static int insn_stack_access_frameno(int insn_flags)
 {
         return insn_flags & INSN_F_FRAMENO_MASK;
 }
 
 static void mark_jmp_point(struct bpf_verifier_env *env, int idx)
 {
         env->insn_aux_data[idx].jmp_point = true;
 }
 
 static bool is_jmp_point(struct bpf_verifier_env *env, int insn_idx)
 {
         return env->insn_aux_data[insn_idx].jmp_point;
 }
 
 /* for any branch, call, exit record the history of jmps in the given state */
 static int push_jmp_history(struct bpf_verifier_env *env, struct bpf_verifier_state *cur,
                             int insn_flags)
 {
         u32 cnt = cur->jmp_history_cnt;
         struct bpf_jmp_history_entry *p;
         size_t alloc_size;
 
         /* combine instruction flags if we already recorded this instruction */
         if (env->cur_hist_ent) {
                 /* atomic instructions push insn_flags twice, for READ and
                  * WRITE sides, but they should agree on stack slot
                  */
                 WARN_ONCE((env->cur_hist_ent->flags & insn_flags) &&
                           (env->cur_hist_ent->flags & insn_flags) != insn_flags,
                           "verifier insn history bug: insn_idx %d cur flags %x new flags %x\n",
                           env->insn_idx, env->cur_hist_ent->flags, insn_flags);
                 env->cur_hist_ent->flags |= insn_flags;
                 return 0;
         }
 
         cnt++;
         alloc_size = kmalloc_size_roundup(size_mul(cnt, sizeof(*p)));
         p = krealloc(cur->jmp_history, alloc_size, GFP_USER);
         if (!p)
                 return -ENOMEM;
         cur->jmp_history = p;
 
         p = &cur->jmp_history[cnt - 1];
         p->idx = env->insn_idx;
         p->prev_idx = env->prev_insn_idx;
         p->flags = insn_flags;
         cur->jmp_history_cnt = cnt;
         env->cur_hist_ent = p;
 
         return 0;
 }
 
 static struct bpf_jmp_history_entry *get_jmp_hist_entry(struct bpf_verifier_state *st,
                                                         u32 hist_end, int insn_idx)
 {
         if (hist_end > 0 && st->jmp_history[hist_end - 1].idx == insn_idx)
                 return &st->jmp_history[hist_end - 1];
         return NULL;
 }
 
 /* Backtrack one insn at a time. If idx is not at the top of recorded
  * history then previous instruction came from straight line execution.
  * Return -ENOENT if we exhausted all instructions within given state.
  *
  * It's legal to have a bit of a looping with the same starting and ending
  * insn index within the same state, e.g.: 3->4->5->3, so just because current
  * instruction index is the same as state's first_idx doesn't mean we are
  * done. If there is still some jump history left, we should keep going. We
  * need to take into account that we might have a jump history between given
  * state's parent and itself, due to checkpointing. In this case, we'll have
  * history entry recording a jump from last instruction of parent state and
  * first instruction of given state.
  */
 static int get_prev_insn_idx(struct bpf_verifier_state *st, int i,
                              u32 *history)
 {
         u32 cnt = *history;
 
         if (i == st->first_insn_idx) {
                 if (cnt == 0)
                         return -ENOENT;
                 if (cnt == 1 && st->jmp_history[0].idx == i)
                         return -ENOENT;
         }
 
         if (cnt && st->jmp_history[cnt - 1].idx == i) {
                 i = st->jmp_history[cnt - 1].prev_idx;
                 (*history)--;
         } else {
                 i--;
         }
         return i;
 }
 
 static const char *disasm_kfunc_name(void *data, const struct bpf_insn *insn)
 {
         const struct btf_type *func;
         struct btf *desc_btf;
 
         if (insn->src_reg != BPF_PSEUDO_KFUNC_CALL)
                 return NULL;
 
         desc_btf = find_kfunc_desc_btf(data, insn->off);
         if (IS_ERR(desc_btf))
                 return "<error>";
 
         func = btf_type_by_id(desc_btf, insn->imm);
         return btf_name_by_offset(desc_btf, func->name_off);
 }
 
 static inline void bt_init(struct backtrack_state *bt, u32 frame)
 {
         bt->frame = frame;
 }
 
 static inline void bt_reset(struct backtrack_state *bt)
 {
         struct bpf_verifier_env *env = bt->env;
 
         memset(bt, 0, sizeof(*bt));
         bt->env = env;
 }
 
 static inline u32 bt_empty(struct backtrack_state *bt)
 {
         u64 mask = 0;
         int i;
 
         for (i = 0; i <= bt->frame; i++)
                 mask |= bt->reg_masks[i] | bt->stack_masks[i];
 
         return mask == 0;
 }
 
 static inline int bt_subprog_enter(struct backtrack_state *bt)
 {
         if (bt->frame == MAX_CALL_FRAMES - 1) {
                 verbose(bt->env, "BUG subprog enter from frame %d\n", bt->frame);
                 WARN_ONCE(1, "verifier backtracking bug");
                 return -EFAULT;
         }
         bt->frame++;
         return 0;
 }
 
 static inline int bt_subprog_exit(struct backtrack_state *bt)
 {
         if (bt->frame == 0) {
                 verbose(bt->env, "BUG subprog exit from frame 0\n");
                 WARN_ONCE(1, "verifier backtracking bug");
                 return -EFAULT;
         }
         bt->frame--;
         return 0;
 }
 
 static inline void bt_set_frame_reg(struct backtrack_state *bt, u32 frame, u32 reg)
 {
         bt->reg_masks[frame] |= 1 << reg;
 }
 
 static inline void bt_clear_frame_reg(struct backtrack_state *bt, u32 frame, u32 reg)
 {
         bt->reg_masks[frame] &= ~(1 << reg);
 }
 
 static inline void bt_set_reg(struct backtrack_state *bt, u32 reg)
 {
         bt_set_frame_reg(bt, bt->frame, reg);
 }
 
 static inline void bt_clear_reg(struct backtrack_state *bt, u32 reg)
 {
         bt_clear_frame_reg(bt, bt->frame, reg);
 }
 
 static inline void bt_set_frame_slot(struct backtrack_state *bt, u32 frame, u32 slot)
 {
         bt->stack_masks[frame] |= 1ull << slot;
 }
 
 static inline void bt_clear_frame_slot(struct backtrack_state *bt, u32 frame, u32 slot)
 {
         bt->stack_masks[frame] &= ~(1ull << slot);
 }
 
 static inline u32 bt_frame_reg_mask(struct backtrack_state *bt, u32 frame)
 {
         return bt->reg_masks[frame];
 }
 
 static inline u32 bt_reg_mask(struct backtrack_state *bt)
 {
         return bt->reg_masks[bt->frame];
 }
 
 static inline u64 bt_frame_stack_mask(struct backtrack_state *bt, u32 frame)
 {
         return bt->stack_masks[frame];
 }
 
 static inline u64 bt_stack_mask(struct backtrack_state *bt)
 {
         return bt->stack_masks[bt->frame];
 }
 
 static inline bool bt_is_reg_set(struct backtrack_state *bt, u32 reg)
 {
         return bt->reg_masks[bt->frame] & (1 << reg);
 }
 
 static inline bool bt_is_frame_slot_set(struct backtrack_state *bt, u32 frame, u32 slot)
 {
         return bt->stack_masks[frame] & (1ull << slot);
 }
 
 /* format registers bitmask, e.g., "r0,r2,r4" for 0x15 mask */
 static void fmt_reg_mask(char *buf, ssize_t buf_sz, u32 reg_mask)
 {
         DECLARE_BITMAP(mask, 64);
         bool first = true;
         int i, n;
 
         buf[0] = '\0';
 
         bitmap_from_u64(mask, reg_mask);
         for_each_set_bit(i, mask, 32) {
                 n = snprintf(buf, buf_sz, "%sr%d", first ? "" : ",", i);
                 first = false;
                 buf += n;
                 buf_sz -= n;
                 if (buf_sz < 0)
                         break;
         }
 }
 /* format stack slots bitmask, e.g., "-8,-24,-40" for 0x15 mask */
 static void fmt_stack_mask(char *buf, ssize_t buf_sz, u64 stack_mask)
 {
         DECLARE_BITMAP(mask, 64);
         bool first = true;
         int i, n;
 
         buf[0] = '\0';
 
         bitmap_from_u64(mask, stack_mask);
         for_each_set_bit(i, mask, 64) {
                 n = snprintf(buf, buf_sz, "%s%d", first ? "" : ",", -(i + 1) * 8);
                 first = false;
                 buf += n;
                 buf_sz -= n;
                 if (buf_sz < 0)
                         break;
         }
 }
 
 static bool calls_callback(struct bpf_verifier_env *env, int insn_idx);
 
 /* For given verifier state backtrack_insn() is called from the last insn to
  * the first insn. Its purpose is to compute a bitmask of registers and
  * stack slots that needs precision in the parent verifier state.
  *
  * @idx is an index of the instruction we are currently processing;
  * @subseq_idx is an index of the subsequent instruction that:
  *   - *would be* executed next, if jump history is viewed in forward order;
  *   - *was* processed previously during backtracking.
  */
 static int backtrack_insn(struct bpf_verifier_env *env, int idx, int subseq_idx,
                           struct bpf_jmp_history_entry *hist, struct backtrack_state *bt)
 {
         const struct bpf_insn_cbs cbs = {
                 .cb_call        = disasm_kfunc_name,
                 .cb_print       = verbose,
                 .private_data   = env,
         };
         struct bpf_insn *insn = env->prog->insnsi + idx;
         u8 class = BPF_CLASS(insn->code);
         u8 opcode = BPF_OP(insn->code);
         u8 mode = BPF_MODE(insn->code);
         u32 dreg = insn->dst_reg;
         u32 sreg = insn->src_reg;
         u32 spi, i, fr;
 
         if (insn->code == 0)
                 return 0;
         if (env->log.level & BPF_LOG_LEVEL2) {
                 fmt_reg_mask(env->tmp_str_buf, TMP_STR_BUF_LEN, bt_reg_mask(bt));
                 verbose(env, "mark_precise: frame%d: regs=%s ",
                         bt->frame, env->tmp_str_buf);
                 fmt_stack_mask(env->tmp_str_buf, TMP_STR_BUF_LEN, bt_stack_mask(bt));
                 verbose(env, "stack=%s before ", env->tmp_str_buf);
                 verbose(env, "%d: ", idx);
                 print_bpf_insn(&cbs, insn, env->allow_ptr_leaks);
         }
 
         if (class == BPF_ALU || class == BPF_ALU64) {
                 if (!bt_is_reg_set(bt, dreg))
                         return 0;
                 if (opcode == BPF_END || opcode == BPF_NEG) {
                         /* sreg is reserved and unused
                          * dreg still need precision before this insn
                          */
                         return 0;
                 } else if (opcode == BPF_MOV) {
                         if (BPF_SRC(insn->code) == BPF_X) {
                                 /* dreg = sreg or dreg = (s8, s16, s32)sreg
                                  * dreg needs precision after this insn
                                  * sreg needs precision before this insn
                                  */
                                 bt_clear_reg(bt, dreg);
                                 if (sreg != BPF_REG_FP)
                                         bt_set_reg(bt, sreg);
                         } else {
                                 /* dreg = K
                                  * dreg needs precision after this insn.
                                  * Corresponding register is already marked
                                  * as precise=true in this verifier state.
                                  * No further markings in parent are necessary
                                  */
                                 bt_clear_reg(bt, dreg);
                         }
                 } else {
                         if (BPF_SRC(insn->code) == BPF_X) {
                                 /* dreg += sreg
                                  * both dreg and sreg need precision
                                  * before this insn
                                  */
                                 if (sreg != BPF_REG_FP)
                                         bt_set_reg(bt, sreg);
                         } /* else dreg += K
                            * dreg still needs precision before this insn
                            */
                 }
         } else if (class == BPF_LDX) {
                 if (!bt_is_reg_set(bt, dreg))
                         return 0;
                 bt_clear_reg(bt, dreg);
 
                 /* scalars can only be spilled into stack w/o losing precision.
                  * Load from any other memory can be zero extended.
                  * The desire to keep that precision is already indicated
                  * by 'precise' mark in corresponding register of this state.
                  * No further tracking necessary.
                  */
                 if (!hist || !(hist->flags & INSN_F_STACK_ACCESS))
                         return 0;
                 /* dreg = *(u64 *)[fp - off] was a fill from the stack.
                  * that [fp - off] slot contains scalar that needs to be
                  * tracked with precision
                  */
                 spi = insn_stack_access_spi(hist->flags);
                 fr = insn_stack_access_frameno(hist->flags);
                 bt_set_frame_slot(bt, fr, spi);
         } else if (class == BPF_STX || class == BPF_ST) {
                 if (bt_is_reg_set(bt, dreg))
                         /* stx & st shouldn't be using _scalar_ dst_reg
                          * to access memory. It means backtracking
                          * encountered a case of pointer subtraction.
                          */
                         return -ENOTSUPP;
                 /* scalars can only be spilled into stack */
                 if (!hist || !(hist->flags & INSN_F_STACK_ACCESS))
                         return 0;
                 spi = insn_stack_access_spi(hist->flags);
                 fr = insn_stack_access_frameno(hist->flags);
                 if (!bt_is_frame_slot_set(bt, fr, spi))
                         return 0;
                 bt_clear_frame_slot(bt, fr, spi);
                 if (class == BPF_STX)
                         bt_set_reg(bt, sreg);
         } else if (class == BPF_JMP || class == BPF_JMP32) {
                 if (bpf_pseudo_call(insn)) {
                         int subprog_insn_idx, subprog;
 
                         subprog_insn_idx = idx + insn->imm + 1;
                         subprog = find_subprog(env, subprog_insn_idx);
                         if (subprog < 0)
                                 return -EFAULT;
 
                         if (subprog_is_global(env, subprog)) {
                                 /* check that jump history doesn't have any
                                  * extra instructions from subprog; the next
                                  * instruction after call to global subprog
                                  * should be literally next instruction in
                                  * caller program
                                  */
                                 WARN_ONCE(idx + 1 != subseq_idx, "verifier backtracking bug");
                                 /* r1-r5 are invalidated after subprog call,
                                  * so for global func call it shouldn't be set
                                  * anymore
                                  */
                                 if (bt_reg_mask(bt) & BPF_REGMASK_ARGS) {
                                         verbose(env, "BUG regs %x\n", bt_reg_mask(bt));
                                         WARN_ONCE(1, "verifier backtracking bug");
                                         return -EFAULT;
                                 }
                                 /* global subprog always sets R0 */
                                 bt_clear_reg(bt, BPF_REG_0);
                                 return 0;
                         } else {
                                 /* static subprog call instruction, which
                                  * means that we are exiting current subprog,
                                  * so only r1-r5 could be still requested as
                                  * precise, r0 and r6-r10 or any stack slot in
                                  * the current frame should be zero by now
                                  */
                                 if (bt_reg_mask(bt) & ~BPF_REGMASK_ARGS) {
                                         verbose(env, "BUG regs %x\n", bt_reg_mask(bt));
                                         WARN_ONCE(1, "verifier backtracking bug");
                                         return -EFAULT;
                                 }
                                 /* we are now tracking register spills correctly,
                                  * so any instance of leftover slots is a bug
                                  */
                                 if (bt_stack_mask(bt) != 0) {
                                         verbose(env, "BUG stack slots %llx\n", bt_stack_mask(bt));
                                         WARN_ONCE(1, "verifier backtracking bug (subprog leftover stack slots)");
                                         return -EFAULT;
                                 }
                                 /* propagate r1-r5 to the caller */
                                 for (i = BPF_REG_1; i <= BPF_REG_5; i++) {
                                         if (bt_is_reg_set(bt, i)) {
                                                 bt_clear_reg(bt, i);
                                                 bt_set_frame_reg(bt, bt->frame - 1, i);
                                         }
                                 }
                                 if (bt_subprog_exit(bt))
                                         return -EFAULT;
                                 return 0;
                         }
                 } else if (is_sync_callback_calling_insn(insn) && idx != subseq_idx - 1) {
                         /* exit from callback subprog to callback-calling helper or
                          * kfunc call. Use idx/subseq_idx check to discern it from
                          * straight line code backtracking.
                          * Unlike the subprog call handling above, we shouldn't
                          * propagate precision of r1-r5 (if any requested), as they are
                          * not actually arguments passed directly to callback subprogs
                          */
                         if (bt_reg_mask(bt) & ~BPF_REGMASK_ARGS) {
                                 verbose(env, "BUG regs %x\n", bt_reg_mask(bt));
                                 WARN_ONCE(1, "verifier backtracking bug");
                                 return -EFAULT;
                         }
                         if (bt_stack_mask(bt) != 0) {
                                 verbose(env, "BUG stack slots %llx\n", bt_stack_mask(bt));
                                 WARN_ONCE(1, "verifier backtracking bug (callback leftover stack slots)");
                                 return -EFAULT;
                         }
                         /* clear r1-r5 in callback subprog's mask */
                         for (i = BPF_REG_1; i <= BPF_REG_5; i++)
                                 bt_clear_reg(bt, i);
                         if (bt_subprog_exit(bt))
                                 return -EFAULT;
                         return 0;
                 } else if (opcode == BPF_CALL) {
                         /* kfunc with imm==0 is invalid and fixup_kfunc_call will
                          * catch this error later. Make backtracking conservative
                          * with ENOTSUPP.
                          */
                         if (insn->src_reg == BPF_PSEUDO_KFUNC_CALL && insn->imm == 0)
                                 return -ENOTSUPP;
                         /* regular helper call sets R0 */
                         bt_clear_reg(bt, BPF_REG_0);
                         if (bt_reg_mask(bt) & BPF_REGMASK_ARGS) {
                                 /* if backtracing was looking for registers R1-R5
                                  * they should have been found already.
                                  */
                                 verbose(env, "BUG regs %x\n", bt_reg_mask(bt));
                                 WARN_ONCE(1, "verifier backtracking bug");
                                 return -EFAULT;
                         }
                 } else if (opcode == BPF_EXIT) {
                         bool r0_precise;
 
                         /* Backtracking to a nested function call, 'idx' is a part of
                          * the inner frame 'subseq_idx' is a part of the outer frame.
                          * In case of a regular function call, instructions giving
                          * precision to registers R1-R5 should have been found already.
                          * In case of a callback, it is ok to have R1-R5 marked for
                          * backtracking, as these registers are set by the function
                          * invoking callback.
                          */
                         if (subseq_idx >= 0 && calls_callback(env, subseq_idx))
                                 for (i = BPF_REG_1; i <= BPF_REG_5; i++)
                                         bt_clear_reg(bt, i);
                         if (bt_reg_mask(bt) & BPF_REGMASK_ARGS) {
                                 verbose(env, "BUG regs %x\n", bt_reg_mask(bt));
                                 WARN_ONCE(1, "verifier backtracking bug");
                                 return -EFAULT;
                         }
 
                         /* BPF_EXIT in subprog or callback always returns
                          * right after the call instruction, so by checking
                          * whether the instruction at subseq_idx-1 is subprog
                          * call or not we can distinguish actual exit from
                          * *subprog* from exit from *callback*. In the former
                          * case, we need to propagate r0 precision, if
                          * necessary. In the former we never do that.
                          */
                         r0_precise = subseq_idx - 1 >= 0 &&
                                      bpf_pseudo_call(&env->prog->insnsi[subseq_idx - 1]) &&
                                      bt_is_reg_set(bt, BPF_REG_0);
 
                         bt_clear_reg(bt, BPF_REG_0);
                         if (bt_subprog_enter(bt))
                                 return -EFAULT;
 
                         if (r0_precise)
                                 bt_set_reg(bt, BPF_REG_0);
                         /* r6-r9 and stack slots will stay set in caller frame
                          * bitmasks until we return back from callee(s)
                          */
                         return 0;
                 } else if (BPF_SRC(insn->code) == BPF_X) {
                         if (!bt_is_reg_set(bt, dreg) && !bt_is_reg_set(bt, sreg))
                                 return 0;
                         /* dreg <cond> sreg
                          * Both dreg and sreg need precision before
                          * this insn. If only sreg was marked precise
                          * before it would be equally necessary to
                          * propagate it to dreg.
                          */
                         bt_set_reg(bt, dreg);
                         bt_set_reg(bt, sreg);
                          /* else dreg <cond> K
                           * Only dreg still needs precision before
                           * this insn, so for the K-based conditional
                           * there is nothing new to be marked.
                           */
                 }
         } else if (class == BPF_LD) {
                 if (!bt_is_reg_set(bt, dreg))
                         return 0;
                 bt_clear_reg(bt, dreg);
                 /* It's ld_imm64 or ld_abs or ld_ind.
                  * For ld_imm64 no further tracking of precision
                  * into parent is necessary
                  */
                 if (mode == BPF_IND || mode == BPF_ABS)
                         /* to be analyzed */
                         return -ENOTSUPP;
         }
         return 0;
 }
 
 /* the scalar precision tracking algorithm:
  * . at the start all registers have precise=false.
  * . scalar ranges are tracked as normal through alu and jmp insns.
  * . once precise value of the scalar register is used in:
  *   .  ptr + scalar alu
  *   . if (scalar cond K|scalar)
  *   .  helper_call(.., scalar, ...) where ARG_CONST is expected
  *   backtrack through the verifier states and mark all registers and
  *   stack slots with spilled constants that these scalar regisers
  *   should be precise.
  * . during state pruning two registers (or spilled stack slots)
  *   are equivalent if both are not precise.
  *
  * Note the verifier cannot simply walk register parentage chain,
  * since many different registers and stack slots could have been
  * used to compute single precise scalar.
  *
  * The approach of starting with precise=true for all registers and then
  * backtrack to mark a register as not precise when the verifier detects
  * that program doesn't care about specific value (e.g., when helper
  * takes register as ARG_ANYTHING parameter) is not safe.
  *
  * It's ok to walk single parentage chain of the verifier states.
  * It's possible that this backtracking will go all the way till 1st insn.
  * All other branches will be explored for needing precision later.
  *
  * The backtracking needs to deal with cases like:
  *   R8=map_value(id=0,off=0,ks=4,vs=1952,imm=0) R9_w=map_value(id=0,off=40,ks=4,vs=1952,imm=0)
  * r9 -= r8
  * r5 = r9
  * if r5 > 0x79f goto pc+7
  *    R5_w=inv(id=0,umax_value=1951,var_off=(0x0; 0x7ff))
  * r5 += 1
  * ...
  * call bpf_perf_event_output#25
  *   where .arg5_type = ARG_CONST_SIZE_OR_ZERO
  *
  * and this case:
  * r6 = 1
  * call foo // uses callee's r6 inside to compute r0
  * r0 += r6
  * if r0 == 0 goto
  *
  * to track above reg_mask/stack_mask needs to be independent for each frame.
  *
  * Also if parent's curframe > frame where backtracking started,
  * the verifier need to mark registers in both frames, otherwise callees
  * may incorrectly prune callers. This is similar to
  * commit 7640ead93924 ("bpf: verifier: make sure callees don't prune with caller differences")
  *
  * For now backtracking falls back into conservative marking.
  */
 static void mark_all_scalars_precise(struct bpf_verifier_env *env,
                                      struct bpf_verifier_state *st)
 {
         struct bpf_func_state *func;
         struct bpf_reg_state *reg;
         int i, j;
 
         if (env->log.level & BPF_LOG_LEVEL2) {
                 verbose(env, "mark_precise: frame%d: falling back to forcing all scalars precise\n",
                         st->curframe);
         }
 
         /* big hammer: mark all scalars precise in this path.
          * pop_stack may still get !precise scalars.
          * We also skip current state and go straight to first parent state,
          * because precision markings in current non-checkpointed state are
          * not needed. See why in the comment in __mark_chain_precision below.
          */
         for (st = st->parent; st; st = st->parent) {
                 for (i = 0; i <= st->curframe; i++) {
                         func = st->frame[i];
                         for (j = 0; j < BPF_REG_FP; j++) {
                                 reg = &func->regs[j];
                                 if (reg->type != SCALAR_VALUE || reg->precise)
                                         continue;
                                 reg->precise = true;
                                 if (env->log.level & BPF_LOG_LEVEL2) {
                                         verbose(env, "force_precise: frame%d: forcing r%d to be precise\n",
                                                 i, j);
                                 }
                         }
                         for (j = 0; j < func->allocated_stack / BPF_REG_SIZE; j++) {
                                 if (!is_spilled_reg(&func->stack[j]))
                                         continue;
                                 reg = &func->stack[j].spilled_ptr;
                                 if (reg->type != SCALAR_VALUE || reg->precise)
                                         continue;
                                 reg->precise = true;
                                 if (env->log.level & BPF_LOG_LEVEL2) {
                                         verbose(env, "force_precise: frame%d: forcing fp%d to be precise\n",
                                                 i, -(j + 1) * 8);
                                 }
                         }
                 }
         }
 }
 
 static void mark_all_scalars_imprecise(struct bpf_verifier_env *env, struct bpf_verifier_state *st)
 {
         struct bpf_func_state *func;
         struct bpf_reg_state *reg;
         int i, j;
 
         for (i = 0; i <= st->curframe; i++) {
                 func = st->frame[i];
                 for (j = 0; j < BPF_REG_FP; j++) {
                         reg = &func->regs[j];
                         if (reg->type != SCALAR_VALUE)
                                 continue;
                         reg->precise = false;
                 }
                 for (j = 0; j < func->allocated_stack / BPF_REG_SIZE; j++) {
                         if (!is_spilled_reg(&func->stack[j]))
                                 continue;
                         reg = &func->stack[j].spilled_ptr;
                         if (reg->type != SCALAR_VALUE)
                                 continue;
                         reg->precise = false;
                 }
         }
 }
 
 static bool idset_contains(struct bpf_idset *s, u32 id)
 {
         u32 i;
 
         for (i = 0; i < s->count; ++i)
                 if (s->ids[i] == (id & ~BPF_ADD_CONST))
                         return true;
 
         return false;
 }
 
 static int idset_push(struct bpf_idset *s, u32 id)
 {
         if (WARN_ON_ONCE(s->count >= ARRAY_SIZE(s->ids)))
                 return -EFAULT;
         s->ids[s->count++] = id & ~BPF_ADD_CONST;
         return 0;
 }
 
 static void idset_reset(struct bpf_idset *s)
 {
         s->count = 0;
 }
 
 /* Collect a set of IDs for all registers currently marked as precise in env->bt.
  * Mark all registers with these IDs as precise.
  */
 static int mark_precise_scalar_ids(struct bpf_verifier_env *env, struct bpf_verifier_state *st)
 {
         struct bpf_idset *precise_ids = &env->idset_scratch;
         struct backtrack_state *bt = &env->bt;
         struct bpf_func_state *func;
         struct bpf_reg_state *reg;
         DECLARE_BITMAP(mask, 64);
         int i, fr;
 
         idset_reset(precise_ids);
 
         for (fr = bt->frame; fr >= 0; fr--) {
                 func = st->frame[fr];
 
                 bitmap_from_u64(mask, bt_frame_reg_mask(bt, fr));
                 for_each_set_bit(i, mask, 32) {
                         reg = &func->regs[i];
                         if (!reg->id || reg->type != SCALAR_VALUE)
                                 continue;
                         if (idset_push(precise_ids, reg->id))
                                 return -EFAULT;
                 }
 
                 bitmap_from_u64(mask, bt_frame_stack_mask(bt, fr));
                 for_each_set_bit(i, mask, 64) {
                         if (i >= func->allocated_stack / BPF_REG_SIZE)
                                 break;
                         if (!is_spilled_scalar_reg(&func->stack[i]))
                                 continue;
                         reg = &func->stack[i].spilled_ptr;
                         if (!reg->id)
                                 continue;
                         if (idset_push(precise_ids, reg->id))
                                 return -EFAULT;
                 }
         }
 
         for (fr = 0; fr <= st->curframe; ++fr) {
                 func = st->frame[fr];
 
                 for (i = BPF_REG_0; i < BPF_REG_10; ++i) {
                         reg = &func->regs[i];
                         if (!reg->id)
                                 continue;
                         if (!idset_contains(precise_ids, reg->id))
                                 continue;
                         bt_set_frame_reg(bt, fr, i);
                 }
                 for (i = 0; i < func->allocated_stack / BPF_REG_SIZE; ++i) {
                         if (!is_spilled_scalar_reg(&func->stack[i]))
                                 continue;
                         reg = &func->stack[i].spilled_ptr;
                         if (!reg->id)
                                 continue;
                         if (!idset_contains(precise_ids, reg->id))
                                 continue;
                         bt_set_frame_slot(bt, fr, i);
                 }
         }
 
         return 0;
 }
 
 /*
  * __mark_chain_precision() backtracks BPF program instruction sequence and
  * chain of verifier states making sure that register *regno* (if regno >= 0)
  * and/or stack slot *spi* (if spi >= 0) are marked as precisely tracked
  * SCALARS, as well as any other registers and slots that contribute to
  * a tracked state of given registers/stack slots, depending on specific BPF
  * assembly instructions (see backtrack_insns() for exact instruction handling
  * logic). This backtracking relies on recorded jmp_history and is able to
  * traverse entire chain of parent states. This process ends only when all the
  * necessary registers/slots and their transitive dependencies are marked as
  * precise.
  *
  * One important and subtle aspect is that precise marks *do not matter* in
  * the currently verified state (current state). It is important to understand
  * why this is the case.
  *
  * First, note that current state is the state that is not yet "checkpointed",
  * i.e., it is not yet put into env->explored_states, and it has no children
  * states as well. It's ephemeral, and can end up either a) being discarded if
  * compatible explored state is found at some point or BPF_EXIT instruction is
  * reached or b) checkpointed and put into env->explored_states, branching out
  * into one or more children states.
  *
  * In the former case, precise markings in current state are completely
  * ignored by state comparison code (see regsafe() for details). Only
  * checkpointed ("old") state precise markings are important, and if old
  * state's register/slot is precise, regsafe() assumes current state's
  * register/slot as precise and checks value ranges exactly and precisely. If
  * states turn out to be compatible, current state's necessary precise
  * markings and any required parent states' precise markings are enforced
  * after the fact with propagate_precision() logic, after the fact. But it's
  * important to realize that in this case, even after marking current state
  * registers/slots as precise, we immediately discard current state. So what
  * actually matters is any of the precise markings propagated into current
  * state's parent states, which are always checkpointed (due to b) case above).
  * As such, for scenario a) it doesn't matter if current state has precise
  * markings set or not.
  *
  * Now, for the scenario b), checkpointing and forking into child(ren)
  * state(s). Note that before current state gets to checkpointing step, any
  * processed instruction always assumes precise SCALAR register/slot
  * knowledge: if precise value or range is useful to prune jump branch, BPF
  * verifier takes this opportunity enthusiastically. Similarly, when
  * register's value is used to calculate offset or memory address, exact
  * knowledge of SCALAR range is assumed, checked, and enforced. So, similar to
  * what we mentioned above about state comparison ignoring precise markings
  * during state comparison, BPF verifier ignores and also assumes precise
  * markings *at will* during instruction verification process. But as verifier
  * assumes precision, it also propagates any precision dependencies across
  * parent states, which are not yet finalized, so can be further restricted
  * based on new knowledge gained from restrictions enforced by their children
  * states. This is so that once those parent states are finalized, i.e., when
  * they have no more active children state, state comparison logic in
  * is_state_visited() would enforce strict and precise SCALAR ranges, if
  * required for correctness.
  *
  * To build a bit more intuition, note also that once a state is checkpointed,
  * the path we took to get to that state is not important. This is crucial
  * property for state pruning. When state is checkpointed and finalized at
  * some instruction index, it can be correctly and safely used to "short
  * circuit" any *compatible* state that reaches exactly the same instruction
  * index. I.e., if we jumped to that instruction from a completely different
  * code path than original finalized state was derived from, it doesn't
  * matter, current state can be discarded because from that instruction
  * forward having a compatible state will ensure we will safely reach the
  * exit. States describe preconditions for further exploration, but completely
  * forget the history of how we got here.
  *
  * This also means that even if we needed precise SCALAR range to get to
  * finalized state, but from that point forward *that same* SCALAR register is
  * never used in a precise context (i.e., it's precise value is not needed for
  * correctness), it's correct and safe to mark such register as "imprecise"
  * (i.e., precise marking set to false). This is what we rely on when we do
  * not set precise marking in current state. If no child state requires
  * precision for any given SCALAR register, it's safe to dictate that it can
  * be imprecise. If any child state does require this register to be precise,
  * we'll mark it precise later retroactively during precise markings
  * propagation from child state to parent states.
  *
  * Skipping precise marking setting in current state is a mild version of
  * relying on the above observation. But we can utilize this property even
  * more aggressively by proactively forgetting any precise marking in the
  * current state (which we inherited from the parent state), right before we
  * checkpoint it and branch off into new child state. This is done by
  * mark_all_scalars_imprecise() to hopefully get more permissive and generic
  * finalized states which help in short circuiting more future states.
  */
 static int __mark_chain_precision(struct bpf_verifier_env *env, int regno)
 {
         struct backtrack_state *bt = &env->bt;
         struct bpf_verifier_state *st = env->cur_state;
         int first_idx = st->first_insn_idx;
         int last_idx = env->insn_idx;
         int subseq_idx = -1;
         struct bpf_func_state *func;
         struct bpf_reg_state *reg;
         bool skip_first = true;
         int i, fr, err;
 
         if (!env->bpf_capable)
                 return 0;
 
         /* set frame number from which we are starting to backtrack */
         bt_init(bt, env->cur_state->curframe);
 
         /* Do sanity checks against current state of register and/or stack
          * slot, but don't set precise flag in current state, as precision
          * tracking in the current state is unnecessary.
          */
         func = st->frame[bt->frame];
         if (regno >= 0) {
                 reg = &func->regs[regno];
                 if (reg->type != SCALAR_VALUE) {
                         WARN_ONCE(1, "backtracing misuse");
                         return -EFAULT;
                 }
                 bt_set_reg(bt, regno);
         }
 
         if (bt_empty(bt))
                 return 0;
 
         for (;;) {
                 DECLARE_BITMAP(mask, 64);
                 u32 history = st->jmp_history_cnt;
                 struct bpf_jmp_history_entry *hist;
 
                 if (env->log.level & BPF_LOG_LEVEL2) {
                         verbose(env, "mark_precise: frame%d: last_idx %d first_idx %d subseq_idx %d \n",
                                 bt->frame, last_idx, first_idx, subseq_idx);
                 }
 
                 /* If some register with scalar ID is marked as precise,
                  * make sure that all registers sharing this ID are also precise.
                  * This is needed to estimate effect of find_equal_scalars().
                  * Do this at the last instruction of each state,
                  * bpf_reg_state::id fields are valid for these instructions.
                  *
                  * Allows to track precision in situation like below:
                  *
                  *     r2 = unknown value
                  *     ...
                  *   --- state #0 ---
                  *     ...
                  *     r1 = r2                 // r1 and r2 now share the same ID
                  *     ...
                  *   --- state #1 {r1.id = A, r2.id = A} ---
                  *     ...
                  *     if (r2 > 10) goto exit; // find_equal_scalars() assigns range to r1
                  *     ...
                  *   --- state #2 {r1.id = A, r2.id = A} ---
                  *     r3 = r10
                  *     r3 += r1                // need to mark both r1 and r2
                  */
                 if (mark_precise_scalar_ids(env, st))
                         return -EFAULT;
 
                 if (last_idx < 0) {
                         /* we are at the entry into subprog, which
                          * is expected for global funcs, but only if
                          * requested precise registers are R1-R5
                          * (which are global func's input arguments)
                          */
                         if (st->curframe == 0 &&
                             st->frame[0]->subprogno > 0 &&
                             st->frame[0]->callsite == BPF_MAIN_FUNC &&
                             bt_stack_mask(bt) == 0 &&
                             (bt_reg_mask(bt) & ~BPF_REGMASK_ARGS) == 0) {
                                 bitmap_from_u64(mask, bt_reg_mask(bt));
                                 for_each_set_bit(i, mask, 32) {
                                         reg = &st->frame[0]->regs[i];
                                         bt_clear_reg(bt, i);
                                         if (reg->type == SCALAR_VALUE)
                                                 reg->precise = true;
                                 }
                                 return 0;
                         }
 
                         verbose(env, "BUG backtracking func entry subprog %d reg_mask %x stack_mask %llx\n",
                                 st->frame[0]->subprogno, bt_reg_mask(bt), bt_stack_mask(bt));
                         WARN_ONCE(1, "verifier backtracking bug");
                         return -EFAULT;
                 }
 
                 for (i = last_idx;;) {
                         if (skip_first) {
                                 err = 0;
                                 skip_first = false;
                         } else {
                                 hist = get_jmp_hist_entry(st, history, i);
                                 err = backtrack_insn(env, i, subseq_idx, hist, bt);
                         }
                         if (err == -ENOTSUPP) {
                                 mark_all_scalars_precise(env, env->cur_state);
                                 bt_reset(bt);
                                 return 0;
                         } else if (err) {
                                 return err;
                         }
                         if (bt_empty(bt))
                                 /* Found assignment(s) into tracked register in this state.
                                  * Since this state is already marked, just return.
                                  * Nothing to be tracked further in the parent state.
                                  */
                                 return 0;
                         subseq_idx = i;
                         i = get_prev_insn_idx(st, i, &history);
                         if (i == -ENOENT)
                                 break;
                         if (i >= env->prog->len) {
                                 /* This can happen if backtracking reached insn 0
                                  * and there are still reg_mask or stack_mask
                                  * to backtrack.
                                  * It means the backtracking missed the spot where
                                  * particular register was initialized with a constant.
                                  */
                                 verbose(env, "BUG backtracking idx %d\n", i);
                                 WARN_ONCE(1, "verifier backtracking bug");
                                 return -EFAULT;
                         }
                 }
                 st = st->parent;
                 if (!st)
                         break;
 
                 for (fr = bt->frame; fr >= 0; fr--) {
                         func = st->frame[fr];
                         bitmap_from_u64(mask, bt_frame_reg_mask(bt, fr));
                         for_each_set_bit(i, mask, 32) {
                                 reg = &func->regs[i];
                                 if (reg->type != SCALAR_VALUE) {
                                         bt_clear_frame_reg(bt, fr, i);
                                         continue;
                                 }
                                 if (reg->precise)
                                         bt_clear_frame_reg(bt, fr, i);
                                 else
                                         reg->precise = true;
                         }
 
                         bitmap_from_u64(mask, bt_frame_stack_mask(bt, fr));
                         for_each_set_bit(i, mask, 64) {
                                 if (i >= func->allocated_stack / BPF_REG_SIZE) {
                                         verbose(env, "BUG backtracking (stack slot %d, total slots %d)\n",
                                                 i, func->allocated_stack / BPF_REG_SIZE);
                                         WARN_ONCE(1, "verifier backtracking bug (stack slot out of bounds)");
                                         return -EFAULT;
                                 }
 
                                 if (!is_spilled_scalar_reg(&func->stack[i])) {
                                         bt_clear_frame_slot(bt, fr, i);
                                         continue;
                                 }
                                 reg = &func->stack[i].spilled_ptr;
                                 if (reg->precise)
                                         bt_clear_frame_slot(bt, fr, i);
                                 else
                                         reg->precise = true;
                         }
                         if (env->log.level & BPF_LOG_LEVEL2) {
                                 fmt_reg_mask(env->tmp_str_buf, TMP_STR_BUF_LEN,
                                              bt_frame_reg_mask(bt, fr));
                                 verbose(env, "mark_precise: frame%d: parent state regs=%s ",
                                         fr, env->tmp_str_buf);
                                 fmt_stack_mask(env->tmp_str_buf, TMP_STR_BUF_LEN,
                                                bt_frame_stack_mask(bt, fr));
                                 verbose(env, "stack=%s: ", env->tmp_str_buf);
                                 print_verifier_state(env, func, true);
                         }
                 }
 
                 if (bt_empty(bt))
                         return 0;
 
                 subseq_idx = first_idx;
                 last_idx = st->last_insn_idx;
                 first_idx = st->first_insn_idx;
         }
 
         /* if we still have requested precise regs or slots, we missed
          * something (e.g., stack access through non-r10 register), so
          * fallback to marking all precise
          */
         if (!bt_empty(bt)) {
                 mark_all_scalars_precise(env, env->cur_state);
                 bt_reset(bt);
         }
 
         return 0;
 }
 
 int mark_chain_precision(struct bpf_verifier_env *env, int regno)
 {
         return __mark_chain_precision(env, regno);
 }
 
 /* mark_chain_precision_batch() assumes that env->bt is set in the caller to
  * desired reg and stack masks across all relevant frames
  */
 static int mark_chain_precision_batch(struct bpf_verifier_env *env)
 {
         return __mark_chain_precision(env, -1);
 }
 
 static bool is_spillable_regtype(enum bpf_reg_type type)
 {
         switch (base_type(type)) {
         case PTR_TO_MAP_VALUE:
         case PTR_TO_STACK:
         case PTR_TO_CTX:
         case PTR_TO_PACKET:
         case PTR_TO_PACKET_META:
         case PTR_TO_PACKET_END:
         case PTR_TO_FLOW_KEYS:
         case CONST_PTR_TO_MAP:
         case PTR_TO_SOCKET:
         case PTR_TO_SOCK_COMMON:
         case PTR_TO_TCP_SOCK:
         case PTR_TO_XDP_SOCK:
         case PTR_TO_BTF_ID:
         case PTR_TO_BUF:
         case PTR_TO_MEM:
         case PTR_TO_FUNC:
         case PTR_TO_MAP_KEY:
         case PTR_TO_ARENA:
                 return true;
         default:
                 return false;
         }
 }
 
 /* Does this register contain a constant zero? */
 static bool register_is_null(struct bpf_reg_state *reg)
 {
         return reg->type == SCALAR_VALUE && tnum_equals_const(reg->var_off, 0);
 }
 
 /* check if register is a constant scalar value */
 static bool is_reg_const(struct bpf_reg_state *reg, bool subreg32)
 {
         return reg->type == SCALAR_VALUE &&
                tnum_is_const(subreg32 ? tnum_subreg(reg->var_off) : reg->var_off);
 }
 
 /* assuming is_reg_const() is true, return constant value of a register */
 static u64 reg_const_value(struct bpf_reg_state *reg, bool subreg32)
 {
         return subreg32 ? tnum_subreg(reg->var_off).value : reg->var_off.value;
 }
 
 static bool __is_pointer_value(bool allow_ptr_leaks,
                                const struct bpf_reg_state *reg)
 {
         if (allow_ptr_leaks)
                 return false;
 
         return reg->type != SCALAR_VALUE;
 }
 
 static void assign_scalar_id_before_mov(struct bpf_verifier_env *env,
                                         struct bpf_reg_state *src_reg)
 {
         if (src_reg->type != SCALAR_VALUE)
                 return;
 
         if (src_reg->id & BPF_ADD_CONST) {
                 /*
                  * The verifier is processing rX = rY insn and
                  * rY->id has special linked register already.
                  * Cleared it, since multiple rX += const are not supported.
                  */
                 src_reg->id = 0;
                 src_reg->off = 0;
         }
 
         if (!src_reg->id && !tnum_is_const(src_reg->var_off))
                 /* Ensure that src_reg has a valid ID that will be copied to
                  * dst_reg and then will be used by find_equal_scalars() to
                  * propagate min/max range.
                  */
                 src_reg->id = ++env->id_gen;
 }
 
 /* Copy src state preserving dst->parent and dst->live fields */
 static void copy_register_state(struct bpf_reg_state *dst, const struct bpf_reg_state *src)
 {
         struct bpf_reg_state *parent = dst->parent;
         enum bpf_reg_liveness live = dst->live;
 
         *dst = *src;
         dst->parent = parent;
         dst->live = live;
 }
 
 static void save_register_state(struct bpf_verifier_env *env,
                                 struct bpf_func_state *state,
                                 int spi, struct bpf_reg_state *reg,
                                 int size)
 {
         int i;
 
         copy_register_state(&state->stack[spi].spilled_ptr, reg);
         if (size == BPF_REG_SIZE)
                 state->stack[spi].spilled_ptr.live |= REG_LIVE_WRITTEN;
 
         for (i = BPF_REG_SIZE; i > BPF_REG_SIZE - size; i--)
                 state->stack[spi].slot_type[i - 1] = STACK_SPILL;
 
         /* size < 8 bytes spill */
         for (; i; i--)
                 mark_stack_slot_misc(env, &state->stack[spi].slot_type[i - 1]);
 }
 
 static bool is_bpf_st_mem(struct bpf_insn *insn)
 {
         return BPF_CLASS(insn->code) == BPF_ST && BPF_MODE(insn->code) == BPF_MEM;
 }
 
 static int get_reg_width(struct bpf_reg_state *reg)
 {
         return fls64(reg->umax_value);
 }
 
 /* check_stack_{read,write}_fixed_off functions track spill/fill of registers,
  * stack boundary and alignment are checked in check_mem_access()
  */
 static int check_stack_write_fixed_off(struct bpf_verifier_env *env,
                                        /* stack frame we're writing to */
                                        struct bpf_func_state *state,
                                        int off, int size, int value_regno,
                                        int insn_idx)
 {
         struct bpf_func_state *cur; /* state of the current function */
         int i, slot = -off - 1, spi = slot / BPF_REG_SIZE, err;
         struct bpf_insn *insn = &env->prog->insnsi[insn_idx];
         struct bpf_reg_state *reg = NULL;
         int insn_flags = insn_stack_access_flags(state->frameno, spi);
 
         /* caller checked that off % size == 0 and -MAX_BPF_STACK <= off < 0,
          * so it's aligned access and [off, off + size) are within stack limits
          */
         if (!env->allow_ptr_leaks &&
             is_spilled_reg(&state->stack[spi]) &&
             size != BPF_REG_SIZE) {
                 verbose(env, "attempt to corrupt spilled pointer on stack\n");
                 return -EACCES;
         }
 
         cur = env->cur_state->frame[env->cur_state->curframe];
         if (value_regno >= 0)
                 reg = &cur->regs[value_regno];
         if (!env->bypass_spec_v4) {
                 bool sanitize = reg && is_spillable_regtype(reg->type);
 
                 for (i = 0; i < size; i++) {
                         u8 type = state->stack[spi].slot_type[i];
 
                         if (type != STACK_MISC && type != STACK_ZERO) {
                                 sanitize = true;
                                 break;
                         }
                 }
 
                 if (sanitize)
                         env->insn_aux_data[insn_idx].sanitize_stack_spill = true;
         }
 
         err = destroy_if_dynptr_stack_slot(env, state, spi);
         if (err)
                 return err;
 
         mark_stack_slot_scratched(env, spi);
         if (reg && !(off % BPF_REG_SIZE) && reg->type == SCALAR_VALUE && env->bpf_capable) {
                 bool reg_value_fits;
 
                 reg_value_fits = get_reg_width(reg) <= BITS_PER_BYTE * size;
                 /* Make sure that reg had an ID to build a relation on spill. */
                 if (reg_value_fits)
                         assign_scalar_id_before_mov(env, reg);
                 save_register_state(env, state, spi, reg, size);
                 /* Break the relation on a narrowing spill. */
                 if (!reg_value_fits)
                         state->stack[spi].spilled_ptr.id = 0;
         } else if (!reg && !(off % BPF_REG_SIZE) && is_bpf_st_mem(insn) &&
                    env->bpf_capable) {
                 struct bpf_reg_state *tmp_reg = &env->fake_reg[0];
 
                 memset(tmp_reg, 0, sizeof(*tmp_reg));
                 __mark_reg_known(tmp_reg, insn->imm);
                 tmp_reg->type = SCALAR_VALUE;
                 save_register_state(env, state, spi, tmp_reg, size);
         } else if (reg && is_spillable_regtype(reg->type)) {
                 /* register containing pointer is being spilled into stack */
                 if (size != BPF_REG_SIZE) {
                         verbose_linfo(env, insn_idx, "; ");
                         verbose(env, "invalid size of register spill\n");
                         return -EACCES;
                 }
                 if (state != cur && reg->type == PTR_TO_STACK) {
                         verbose(env, "cannot spill pointers to stack into stack frame of the caller\n");
                         return -EINVAL;
                 }
                 save_register_state(env, state, spi, reg, size);
         } else {
                 u8 type = STACK_MISC;
 
                 /* regular write of data into stack destroys any spilled ptr */
                 state->stack[spi].spilled_ptr.type = NOT_INIT;
                 /* Mark slots as STACK_MISC if they belonged to spilled ptr/dynptr/iter. */
                 if (is_stack_slot_special(&state->stack[spi]))
                         for (i = 0; i < BPF_REG_SIZE; i++)
                                 scrub_spilled_slot(&state->stack[spi].slot_type[i]);
 
                 /* only mark the slot as written if all 8 bytes were written
                  * otherwise read propagation may incorrectly stop too soon
                  * when stack slots are partially written.
                  * This heuristic means that read propagation will be
                  * conservative, since it will add reg_live_read marks
                  * to stack slots all the way to first state when programs
                  * writes+reads less than 8 bytes
                  */
                 if (size == BPF_REG_SIZE)
                         state->stack[spi].spilled_ptr.live |= REG_LIVE_WRITTEN;
 
                 /* when we zero initialize stack slots mark them as such */
                 if ((reg && register_is_null(reg)) ||
                     (!reg && is_bpf_st_mem(insn) && insn->imm == 0)) {
                         /* STACK_ZERO case happened because register spill
                          * wasn't properly aligned at the stack slot boundary,
                          * so it's not a register spill anymore; force
                          * originating register to be precise to make
                          * STACK_ZERO correct for subsequent states
                          */
                         err = mark_chain_precision(env, value_regno);
                         if (err)
                                 return err;
                         type = STACK_ZERO;
                 }
 
                 /* Mark slots affected by this stack write. */
                 for (i = 0; i < size; i++)
                         state->stack[spi].slot_type[(slot - i) % BPF_REG_SIZE] = type;
                 insn_flags = 0; /* not a register spill */
         }
 
         if (insn_flags)
                 return push_jmp_history(env, env->cur_state, insn_flags);
         return 0;
 }
 
 /* Write the stack: 'stack[ptr_regno + off] = value_regno'. 'ptr_regno' is
  * known to contain a variable offset.
  * This function checks whether the write is permitted and conservatively
  * tracks the effects of the write, considering that each stack slot in the
  * dynamic range is potentially written to.
  *
  * 'off' includes 'regno->off'.
  * 'value_regno' can be -1, meaning that an unknown value is being written to
  * the stack.
  *
  * Spilled pointers in range are not marked as written because we don't know
  * what's going to be actually written. This means that read propagation for
  * future reads cannot be terminated by this write.
  *
  * For privileged programs, uninitialized stack slots are considered
  * initialized by this write (even though we don't know exactly what offsets
  * are going to be written to). The idea is that we don't want the verifier to
  * reject future reads that access slots written to through variable offsets.
  */
 static int check_stack_write_var_off(struct bpf_verifier_env *env,
                                      /* func where register points to */
                                      struct bpf_func_state *state,
                                      int ptr_regno, int off, int size,
                                      int value_regno, int insn_idx)
 {
         struct bpf_func_state *cur; /* state of the current function */
         int min_off, max_off;
         int i, err;
         struct bpf_reg_state *ptr_reg = NULL, *value_reg = NULL;
         struct bpf_insn *insn = &env->prog->insnsi[insn_idx];
         bool writing_zero = false;
         /* set if the fact that we're writing a zero is used to let any
          * stack slots remain STACK_ZERO
          */
         bool zero_used = false;
 
         cur = env->cur_state->frame[env->cur_state->curframe];
         ptr_reg = &cur->regs[ptr_regno];
         min_off = ptr_reg->smin_value + off;
         max_off = ptr_reg->smax_value + off + size;
         if (value_regno >= 0)
                 value_reg = &cur->regs[value_regno];
         if ((value_reg && register_is_null(value_reg)) ||
             (!value_reg && is_bpf_st_mem(insn) && insn->imm == 0))
                 writing_zero = true;
 
         for (i = min_off; i < max_off; i++) {
                 int spi;
 
                 spi = __get_spi(i);
                 err = destroy_if_dynptr_stack_slot(env, state, spi);
                 if (err)
                         return err;
         }
 
         /* Variable offset writes destroy any spilled pointers in range. */
         for (i = min_off; i < max_off; i++) {
                 u8 new_type, *stype;
                 int slot, spi;
 
                 slot = -i - 1;
                 spi = slot / BPF_REG_SIZE;
                 stype = &state->stack[spi].slot_type[slot % BPF_REG_SIZE];
                 mark_stack_slot_scratched(env, spi);
 
                 if (!env->allow_ptr_leaks && *stype != STACK_MISC && *stype != STACK_ZERO) {
                         /* Reject the write if range we may write to has not
                          * been initialized beforehand. If we didn't reject
                          * here, the ptr status would be erased below (even
                          * though not all slots are actually overwritten),
                          * possibly opening the door to leaks.
                          *
                          * We do however catch STACK_INVALID case below, and
                          * only allow reading possibly uninitialized memory
                          * later for CAP_PERFMON, as the write may not happen to
                          * that slot.
                          */
                         verbose(env, "spilled ptr in range of var-offset stack write; insn %d, ptr off: %d",
                                 insn_idx, i);
                         return -EINVAL;
                 }
 
                 /* If writing_zero and the spi slot contains a spill of value 0,
                  * maintain the spill type.
                  */
                 if (writing_zero && *stype == STACK_SPILL &&
                     is_spilled_scalar_reg(&state->stack[spi])) {
                         struct bpf_reg_state *spill_reg = &state->stack[spi].spilled_ptr;
 
                         if (tnum_is_const(spill_reg->var_off) && spill_reg->var_off.value == 0) {
                                 zero_used = true;
                                 continue;
                         }
                 }
 
                 /* Erase all other spilled pointers. */
                 state->stack[spi].spilled_ptr.type = NOT_INIT;
 
                 /* Update the slot type. */
                 new_type = STACK_MISC;
                 if (writing_zero && *stype == STACK_ZERO) {
                         new_type = STACK_ZERO;
                         zero_used = true;
                 }
                 /* If the slot is STACK_INVALID, we check whether it's OK to
                  * pretend that it will be initialized by this write. The slot
                  * might not actually be written to, and so if we mark it as
                  * initialized future reads might leak uninitialized memory.
                  * For privileged programs, we will accept such reads to slots
                  * that may or may not be written because, if we're reject
                  * them, the error would be too confusing.
                  */
                 if (*stype == STACK_INVALID && !env->allow_uninit_stack) {
                         verbose(env, "uninit stack in range of var-offset write prohibited for !root; insn %d, off: %d",
                                         insn_idx, i);
                         return -EINVAL;
                 }
                 *stype = new_type;
         }
         if (zero_used) {
                 /* backtracking doesn't work for STACK_ZERO yet. */
                 err = mark_chain_precision(env, value_regno);
                 if (err)
                         return err;
         }
         return 0;
 }
 
 /* When register 'dst_regno' is assigned some values from stack[min_off,
  * max_off), we set the register's type according to the types of the
  * respective stack slots. If all the stack values are known to be zeros, then
  * so is the destination reg. Otherwise, the register is considered to be
  * SCALAR. This function does not deal with register filling; the caller must
  * ensure that all spilled registers in the stack range have been marked as
  * read.
  */
 static void mark_reg_stack_read(struct bpf_verifier_env *env,
                                 /* func where src register points to */
                                 struct bpf_func_state *ptr_state,
                                 int min_off, int max_off, int dst_regno)
 {
         struct bpf_verifier_state *vstate = env->cur_state;
         struct bpf_func_state *state = vstate->frame[vstate->curframe];
         int i, slot, spi;
         u8 *stype;
         int zeros = 0;
 
         for (i = min_off; i < max_off; i++) {
                 slot = -i - 1;
                 spi = slot / BPF_REG_SIZE;
                 mark_stack_slot_scratched(env, spi);
                 stype = ptr_state->stack[spi].slot_type;
                 if (stype[slot % BPF_REG_SIZE] != STACK_ZERO)
                         break;
                 zeros++;
         }
         if (zeros == max_off - min_off) {
                 /* Any access_size read into register is zero extended,
                  * so the whole register == const_zero.
                  */
                 __mark_reg_const_zero(env, &state->regs[dst_regno]);
         } else {
                 /* have read misc data from the stack */
                 mark_reg_unknown(env, state->regs, dst_regno);
         }
         state->regs[dst_regno].live |= REG_LIVE_WRITTEN;
 }
 
 /* Read the stack at 'off' and put the results into the register indicated by
  * 'dst_regno'. It handles reg filling if the addressed stack slot is a
  * spilled reg.
  *
  * 'dst_regno' can be -1, meaning that the read value is not going to a
  * register.
  *
  * The access is assumed to be within the current stack bounds.
  */
 static int check_stack_read_fixed_off(struct bpf_verifier_env *env,
                                       /* func where src register points to */
                                       struct bpf_func_state *reg_state,
                                       int off, int size, int dst_regno)
 {
         struct bpf_verifier_state *vstate = env->cur_state;
         struct bpf_func_state *state = vstate->frame[vstate->curframe];
         int i, slot = -off - 1, spi = slot / BPF_REG_SIZE;
         struct bpf_reg_state *reg;
         u8 *stype, type;
         int insn_flags = insn_stack_access_flags(reg_state->frameno, spi);
 
         stype = reg_state->stack[spi].slot_type;
         reg = &reg_state->stack[spi].spilled_ptr;
 
         mark_stack_slot_scratched(env, spi);
 
         if (is_spilled_reg(&reg_state->stack[spi])) {
                 u8 spill_size = 1;
 
                 for (i = BPF_REG_SIZE - 1; i > 0 && stype[i - 1] == STACK_SPILL; i--)
                         spill_size++;
 
                 if (size != BPF_REG_SIZE || spill_size != BPF_REG_SIZE) {
                         if (reg->type != SCALAR_VALUE) {
                                 verbose_linfo(env, env->insn_idx, "; ");
                                 verbose(env, "invalid size of register fill\n");
                                 return -EACCES;
                         }
 
                         mark_reg_read(env, reg, reg->parent, REG_LIVE_READ64);
                         if (dst_regno < 0)
                                 return 0;
 
                         if (size <= spill_size &&
                             bpf_stack_narrow_access_ok(off, size, spill_size)) {
                                 /* The earlier check_reg_arg() has decided the
                                  * subreg_def for this insn.  Save it first.
                                  */
                                 s32 subreg_def = state->regs[dst_regno].subreg_def;
 
                                 copy_register_state(&state->regs[dst_regno], reg);
                                 state->regs[dst_regno].subreg_def = subreg_def;
 
                                 /* Break the relation on a narrowing fill.
                                  * coerce_reg_to_size will adjust the boundaries.
                                  */
                                 if (get_reg_width(reg) > size * BITS_PER_BYTE)
                                         state->regs[dst_regno].id = 0;
                         } else {
                                 int spill_cnt = 0, zero_cnt = 0;
 
                                 for (i = 0; i < size; i++) {
                                         type = stype[(slot - i) % BPF_REG_SIZE];
                                         if (type == STACK_SPILL) {
                                                 spill_cnt++;
                                                 continue;
                                         }
                                         if (type == STACK_MISC)
                                                 continue;
                                         if (type == STACK_ZERO) {
                                                 zero_cnt++;
                                                 continue;
                                         }
                                         if (type == STACK_INVALID && env->allow_uninit_stack)
                                                 continue;
                                         verbose(env, "invalid read from stack off %d+%d size %d\n",
                                                 off, i, size);
                                         return -EACCES;
                                 }
 
                                 if (spill_cnt == size &&
                                     tnum_is_const(reg->var_off) && reg->var_off.value == 0) {
                                         __mark_reg_const_zero(env, &state->regs[dst_regno]);
                                         /* this IS register fill, so keep insn_flags */
                                 } else if (zero_cnt == size) {
                                         /* similarly to mark_reg_stack_read(), preserve zeroes */
                                         __mark_reg_const_zero(env, &state->regs[dst_regno]);
                                         insn_flags = 0; /* not restoring original register state */
                                 } else {
                                         mark_reg_unknown(env, state->regs, dst_regno);
                                         insn_flags = 0; /* not restoring original register state */
                                 }
                         }
                         state->regs[dst_regno].live |= REG_LIVE_WRITTEN;
                 } else if (dst_regno >= 0) {
                         /* restore register state from stack */
                         copy_register_state(&state->regs[dst_regno], reg);
                         /* mark reg as written since spilled pointer state likely
                          * has its liveness marks cleared by is_state_visited()
                          * which resets stack/reg liveness for state transitions
                          */
                         state->regs[dst_regno].live |= REG_LIVE_WRITTEN;
                 } else if (__is_pointer_value(env->allow_ptr_leaks, reg)) {
                         /* If dst_regno==-1, the caller is asking us whether
                          * it is acceptable to use this value as a SCALAR_VALUE
                          * (e.g. for XADD).
                          * We must not allow unprivileged callers to do that
                          * with spilled pointers.
                          */
                         verbose(env, "leaking pointer from stack off %d\n",
                                 off);
                         return -EACCES;
                 }
                 mark_reg_read(env, reg, reg->parent, REG_LIVE_READ64);
         } else {
                 for (i = 0; i < size; i++) {
                         type = stype[(slot - i) % BPF_REG_SIZE];
                         if (type == STACK_MISC)
                                 continue;
                         if (type == STACK_ZERO)
                                 continue;
                         if (type == STACK_INVALID && env->allow_uninit_stack)
                                 continue;
                         verbose(env, "invalid read from stack off %d+%d size %d\n",
                                 off, i, size);
                         return -EACCES;
                 }
                 mark_reg_read(env, reg, reg->parent, REG_LIVE_READ64);
                 if (dst_regno >= 0)
                         mark_reg_stack_read(env, reg_state, off, off + size, dst_regno);
                 insn_flags = 0; /* we are not restoring spilled register */
         }
         if (insn_flags)
                 return push_jmp_history(env, env->cur_state, insn_flags);
         return 0;
 }
 
 enum bpf_access_src {
         ACCESS_DIRECT = 1,  /* the access is performed by an instruction */
         ACCESS_HELPER = 2,  /* the access is performed by a helper */
 };
 
 static int check_stack_range_initialized(struct bpf_verifier_env *env,
                                          int regno, int off, int access_size,
                                          bool zero_size_allowed,
                                          enum bpf_access_src type,
                                          struct bpf_call_arg_meta *meta);
 
 static struct bpf_reg_state *reg_state(struct bpf_verifier_env *env, int regno)
 {
         return cur_regs(env) + regno;
 }
 
 /* Read the stack at 'ptr_regno + off' and put the result into the register
  * 'dst_regno'.
  * 'off' includes the pointer register's fixed offset(i.e. 'ptr_regno.off'),
  * but not its variable offset.
  * 'size' is assumed to be <= reg size and the access is assumed to be aligned.
  *
  * As opposed to check_stack_read_fixed_off, this function doesn't deal with
  * filling registers (i.e. reads of spilled register cannot be detected when
  * the offset is not fixed). We conservatively mark 'dst_regno' as containing
  * SCALAR_VALUE. That's why we assert that the 'ptr_regno' has a variable
  * offset; for a fixed offset check_stack_read_fixed_off should be used
  * instead.
  */
 static int check_stack_read_var_off(struct bpf_verifier_env *env,
                                     int ptr_regno, int off, int size, int dst_regno)
 {
         /* The state of the source register. */
         struct bpf_reg_state *reg = reg_state(env, ptr_regno);
         struct bpf_func_state *ptr_state = func(env, reg);
         int err;
         int min_off, max_off;
 
         /* Note that we pass a NULL meta, so raw access will not be permitted.
          */
         err = check_stack_range_initialized(env, ptr_regno, off, size,
                                             false, ACCESS_DIRECT, NULL);
         if (err)
                 return err;
 
         min_off = reg->smin_value + off;
         max_off = reg->smax_value + off;
         mark_reg_stack_read(env, ptr_state, min_off, max_off + size, dst_regno);
         return 0;
 }
 
 /* check_stack_read dispatches to check_stack_read_fixed_off or
  * check_stack_read_var_off.
  *
  * The caller must ensure that the offset falls within the allocated stack
  * bounds.
  *
  * 'dst_regno' is a register which will receive the value from the stack. It
  * can be -1, meaning that the read value is not going to a register.
  */
 static int check_stack_read(struct bpf_verifier_env *env,
                             int ptr_regno, int off, int size,
                             int dst_regno)
 {
         struct bpf_reg_state *reg = reg_state(env, ptr_regno);
         struct bpf_func_state *state = func(env, reg);
         int err;
         /* Some accesses are only permitted with a static offset. */
         bool var_off = !tnum_is_const(reg->var_off);
 
         /* The offset is required to be static when reads don't go to a
          * register, in order to not leak pointers (see
          * check_stack_read_fixed_off).
          */
         if (dst_regno < 0 && var_off) {
                 char tn_buf[48];
 
                 tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
                 verbose(env, "variable offset stack pointer cannot be passed into helper function; var_off=%s off=%d size=%d\n",
                         tn_buf, off, size);
                 return -EACCES;
         }
         /* Variable offset is prohibited for unprivileged mode for simplicity
          * since it requires corresponding support in Spectre masking for stack
          * ALU. See also retrieve_ptr_limit(). The check in
          * check_stack_access_for_ptr_arithmetic() called by
          * adjust_ptr_min_max_vals() prevents users from creating stack pointers
          * with variable offsets, therefore no check is required here. Further,
          * just checking it here would be insufficient as speculative stack
          * writes could still lead to unsafe speculative behaviour.
          */
         if (!var_off) {
                 off += reg->var_off.value;
                 err = check_stack_read_fixed_off(env, state, off, size,
                                                  dst_regno);
         } else {
                 /* Variable offset stack reads need more conservative handling
                  * than fixed offset ones. Note that dst_regno >= 0 on this
                  * branch.
                  */
                 err = check_stack_read_var_off(env, ptr_regno, off, size,
                                                dst_regno);
         }
         return err;
 }
 
 
 /* check_stack_write dispatches to check_stack_write_fixed_off or
  * check_stack_write_var_off.
  *
  * 'ptr_regno' is the register used as a pointer into the stack.
  * 'off' includes 'ptr_regno->off', but not its variable offset (if any).
  * 'value_regno' is the register whose value we're writing to the stack. It can
  * be -1, meaning that we're not writing from a register.
  *
  * The caller must ensure that the offset falls within the maximum stack size.
  */
 static int check_stack_write(struct bpf_verifier_env *env,
                              int ptr_regno, int off, int size,
                              int value_regno, int insn_idx)
 {
         struct bpf_reg_state *reg = reg_state(env, ptr_regno);
         struct bpf_func_state *state = func(env, reg);
         int err;
 
         if (tnum_is_const(reg->var_off)) {
                 off += reg->var_off.value;
                 err = check_stack_write_fixed_off(env, state, off, size,
                                                   value_regno, insn_idx);
         } else {
                 /* Variable offset stack reads need more conservative handling
                  * than fixed offset ones.
                  */
                 err = check_stack_write_var_off(env, state,
                                                 ptr_regno, off, size,
                                                 value_regno, insn_idx);
         }
         return err;
 }
 
 static int check_map_access_type(struct bpf_verifier_env *env, u32 regno,
                                  int off, int size, enum bpf_access_type type)
 {
         struct bpf_reg_state *regs = cur_regs(env);
         struct bpf_map *map = regs[regno].map_ptr;
         u32 cap = bpf_map_flags_to_cap(map);
 
         if (type == BPF_WRITE && !(cap & BPF_MAP_CAN_WRITE)) {
                 verbose(env, "write into map forbidden, value_size=%d off=%d size=%d\n",
                         map->value_size, off, size);
                 return -EACCES;
         }
 
         if (type == BPF_READ && !(cap & BPF_MAP_CAN_READ)) {
                 verbose(env, "read from map forbidden, value_size=%d off=%d size=%d\n",
                         map->value_size, off, size);
                 return -EACCES;
         }
 
         return 0;
 }
 
 /* check read/write into memory region (e.g., map value, ringbuf sample, etc) */
 static int __check_mem_access(struct bpf_verifier_env *env, int regno,
                               int off, int size, u32 mem_size,
                               bool zero_size_allowed)
 {
         bool size_ok = size > 0 || (size == 0 && zero_size_allowed);
         struct bpf_reg_state *reg;
 
         if (off >= 0 && size_ok && (u64)off + size <= mem_size)
                 return 0;
 
         reg = &cur_regs(env)[regno];
         switch (reg->type) {
         case PTR_TO_MAP_KEY:
                 verbose(env, "invalid access to map key, key_size=%d off=%d size=%d\n",
                         mem_size, off, size);
                 break;
         case PTR_TO_MAP_VALUE:
                 verbose(env, "invalid access to map value, value_size=%d off=%d size=%d\n",
                         mem_size, off, size);
                 break;
         case PTR_TO_PACKET:
         case PTR_TO_PACKET_META:
         case PTR_TO_PACKET_END:
                 verbose(env, "invalid access to packet, off=%d size=%d, R%d(id=%d,off=%d,r=%d)\n",
                         off, size, regno, reg->id, off, mem_size);
                 break;
         case PTR_TO_MEM:
         default:
                 verbose(env, "invalid access to memory, mem_size=%u off=%d size=%d\n",
                         mem_size, off, size);
         }
 
         return -EACCES;
 }
 
 /* check read/write into a memory region with possible variable offset */
 static int check_mem_region_access(struct bpf_verifier_env *env, u32 regno,
                                    int off, int size, u32 mem_size,
                                    bool zero_size_allowed)
 {
         struct bpf_verifier_state *vstate = env->cur_state;
         struct bpf_func_state *state = vstate->frame[vstate->curframe];
         struct bpf_reg_state *reg = &state->regs[regno];
         int err;
 
         /* We may have adjusted the register pointing to memory region, so we
          * need to try adding each of min_value and max_value to off
          * to make sure our theoretical access will be safe.
          *
          * The minimum value is only important with signed
          * comparisons where we can't assume the floor of a
          * value is 0.  If we are using signed variables for our
          * index'es we need to make sure that whatever we use
          * will have a set floor within our range.
          */
         if (reg->smin_value < 0 &&
             (reg->smin_value == S64_MIN ||
              (off + reg->smin_value != (s64)(s32)(off + reg->smin_value)) ||
               reg->smin_value + off < 0)) {
                 verbose(env, "R%d min value is negative, either use unsigned index or do a if (index >=0) check.\n",
                         regno);
                 return -EACCES;
         }
         err = __check_mem_access(env, regno, reg->smin_value + off, size,
                                  mem_size, zero_size_allowed);
         if (err) {
                 verbose(env, "R%d min value is outside of the allowed memory range\n",
                         regno);
                 return err;
         }
 
         /* If we haven't set a max value then we need to bail since we can't be
          * sure we won't do bad things.
          * If reg->umax_value + off could overflow, treat that as unbounded too.
          */
         if (reg->umax_value >= BPF_MAX_VAR_OFF) {
                 verbose(env, "R%d unbounded memory access, make sure to bounds check any such access\n",
                         regno);
                 return -EACCES;
         }
         err = __check_mem_access(env, regno, reg->umax_value + off, size,
                                  mem_size, zero_size_allowed);
         if (err) {
                 verbose(env, "R%d max value is outside of the allowed memory range\n",
                         regno);
                 return err;
         }
 
         return 0;
 }
 
 static int __check_ptr_off_reg(struct bpf_verifier_env *env,
                                const struct bpf_reg_state *reg, int regno,
                                bool fixed_off_ok)
 {
         /* Access to this pointer-typed register or passing it to a helper
          * is only allowed in its original, unmodified form.
          */
 
         if (reg->off < 0) {
                 verbose(env, "negative offset %s ptr R%d off=%d disallowed\n",
                         reg_type_str(env, reg->type), regno, reg->off);
                 return -EACCES;
         }
 
         if (!fixed_off_ok && reg->off) {
                 verbose(env, "dereference of modified %s ptr R%d off=%d disallowed\n",
                         reg_type_str(env, reg->type), regno, reg->off);
                 return -EACCES;
         }
 
         if (!tnum_is_const(reg->var_off) || reg->var_off.value) {
                 char tn_buf[48];
 
                 tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
                 verbose(env, "variable %s access var_off=%s disallowed\n",
                         reg_type_str(env, reg->type), tn_buf);
                 return -EACCES;
         }
 
         return 0;
 }
 
 static int check_ptr_off_reg(struct bpf_verifier_env *env,
                              const struct bpf_reg_state *reg, int regno)
 {
         return __check_ptr_off_reg(env, reg, regno, false);
 }
 
 static int map_kptr_match_type(struct bpf_verifier_env *env,
                                struct btf_field *kptr_field,
                                struct bpf_reg_state *reg, u32 regno)
 {
         const char *targ_name = btf_type_name(kptr_field->kptr.btf, kptr_field->kptr.btf_id);
         int perm_flags;
         const char *reg_name = "";
 
         if (btf_is_kernel(reg->btf)) {
                 perm_flags = PTR_MAYBE_NULL | PTR_TRUSTED | MEM_RCU;
 
                 /* Only unreferenced case accepts untrusted pointers */
                 if (kptr_field->type == BPF_KPTR_UNREF)
                         perm_flags |= PTR_UNTRUSTED;
         } else {
                 perm_flags = PTR_MAYBE_NULL | MEM_ALLOC;
                 if (kptr_field->type == BPF_KPTR_PERCPU)
                         perm_flags |= MEM_PERCPU;
         }
 
         if (base_type(reg->type) != PTR_TO_BTF_ID || (type_flag(reg->type) & ~perm_flags))
                 goto bad_type;
 
         /* We need to verify reg->type and reg->btf, before accessing reg->btf */
         reg_name = btf_type_name(reg->btf, reg->btf_id);
 
         /* For ref_ptr case, release function check should ensure we get one
          * referenced PTR_TO_BTF_ID, and that its fixed offset is 0. For the
          * normal store of unreferenced kptr, we must ensure var_off is zero.
          * Since ref_ptr cannot be accessed directly by BPF insns, checks for
          * reg->off and reg->ref_obj_id are not needed here.
          */
         if (__check_ptr_off_reg(env, reg, regno, true))
                 return -EACCES;
 
         /* A full type match is needed, as BTF can be vmlinux, module or prog BTF, and
          * we also need to take into account the reg->off.
          *
          * We want to support cases like:
          *
          * struct foo {
          *         struct bar br;
          *         struct baz bz;
          * };
          *
          * struct foo *v;
          * v = func();        // PTR_TO_BTF_ID
          * val->foo = v;      // reg->off is zero, btf and btf_id match type
          * val->bar = &v->br; // reg->off is still zero, but we need to retry with
          *                    // first member type of struct after comparison fails
          * val->baz = &v->bz; // reg->off is non-zero, so struct needs to be walked
          *                    // to match type
          *
          * In the kptr_ref case, check_func_arg_reg_off already ensures reg->off
          * is zero. We must also ensure that btf_struct_ids_match does not walk
          * the struct to match type against first member of struct, i.e. reject
          * second case from above. Hence, when type is BPF_KPTR_REF, we set
          * strict mode to true for type match.
          */
         if (!btf_struct_ids_match(&env->log, reg->btf, reg->btf_id, reg->off,
                                   kptr_field->kptr.btf, kptr_field->kptr.btf_id,
                                   kptr_field->type != BPF_KPTR_UNREF))
                 goto bad_type;
         return 0;
 bad_type:
         verbose(env, "invalid kptr access, R%d type=%s%s ", regno,
                 reg_type_str(env, reg->type), reg_name);
         verbose(env, "expected=%s%s", reg_type_str(env, PTR_TO_BTF_ID), targ_name);
         if (kptr_field->type == BPF_KPTR_UNREF)
                 verbose(env, " or %s%s\n", reg_type_str(env, PTR_TO_BTF_ID | PTR_UNTRUSTED),
                         targ_name);
         else
                 verbose(env, "\n");
         return -EINVAL;
 }
 
 static bool in_sleepable(struct bpf_verifier_env *env)
 {
         return env->prog->sleepable ||
                (env->cur_state && env->cur_state->in_sleepable);
 }
 
 /* The non-sleepable programs and sleepable programs with explicit bpf_rcu_read_lock()
  * can dereference RCU protected pointers and result is PTR_TRUSTED.
  */
 static bool in_rcu_cs(struct bpf_verifier_env *env)
 {
         return env->cur_state->active_rcu_lock ||
                env->cur_state->active_lock.ptr ||
                !in_sleepable(env);
 }
 
 /* Once GCC supports btf_type_tag the following mechanism will be replaced with tag check */
 BTF_SET_START(rcu_protected_types)
 BTF_ID(struct, prog_test_ref_kfunc)
 #ifdef CONFIG_CGROUPS
 BTF_ID(struct, cgroup)
 #endif
 #ifdef CONFIG_BPF_JIT
 BTF_ID(struct, bpf_cpumask)
 #endif
 BTF_ID(struct, task_struct)
 BTF_ID(struct, bpf_crypto_ctx)
 BTF_SET_END(rcu_protected_types)
 
 static bool rcu_protected_object(const struct btf *btf, u32 btf_id)
 {
         if (!btf_is_kernel(btf))
                 return true;
         return btf_id_set_contains(&rcu_protected_types, btf_id);
 }
 
 static struct btf_record *kptr_pointee_btf_record(struct btf_field *kptr_field)
 {
         struct btf_struct_meta *meta;
 
         if (btf_is_kernel(kptr_field->kptr.btf))
                 return NULL;
 
         meta = btf_find_struct_meta(kptr_field->kptr.btf,
                                     kptr_field->kptr.btf_id);
 
         return meta ? meta->record : NULL;
 }
 
 static bool rcu_safe_kptr(const struct btf_field *field)
 {
         const struct btf_field_kptr *kptr = &field->kptr;
 
         return field->type == BPF_KPTR_PERCPU ||
                (field->type == BPF_KPTR_REF && rcu_protected_object(kptr->btf, kptr->btf_id));
 }
 
 static u32 btf_ld_kptr_type(struct bpf_verifier_env *env, struct btf_field *kptr_field)
 {
         struct btf_record *rec;
         u32 ret;
 
         ret = PTR_MAYBE_NULL;
         if (rcu_safe_kptr(kptr_field) && in_rcu_cs(env)) {
                 ret |= MEM_RCU;
                 if (kptr_field->type == BPF_KPTR_PERCPU)
                         ret |= MEM_PERCPU;
                 else if (!btf_is_kernel(kptr_field->kptr.btf))
                         ret |= MEM_ALLOC;
 
                 rec = kptr_pointee_btf_record(kptr_field);
                 if (rec && btf_record_has_field(rec, BPF_GRAPH_NODE))
                         ret |= NON_OWN_REF;
         } else {
                 ret |= PTR_UNTRUSTED;
         }
 
         return ret;
 }
 
 static int check_map_kptr_access(struct bpf_verifier_env *env, u32 regno,
                                  int value_regno, int insn_idx,
                                  struct btf_field *kptr_field)
 {
         struct bpf_insn *insn = &env->prog->insnsi[insn_idx];
         int class = BPF_CLASS(insn->code);
         struct bpf_reg_state *val_reg;
 
         /* Things we already checked for in check_map_access and caller:
          *  - Reject cases where variable offset may touch kptr
          *  - size of access (must be BPF_DW)
          *  - tnum_is_const(reg->var_off)
          *  - kptr_field->offset == off + reg->var_off.value
          */
         /* Only BPF_[LDX,STX,ST] | BPF_MEM | BPF_DW is supported */
         if (BPF_MODE(insn->code) != BPF_MEM) {
                 verbose(env, "kptr in map can only be accessed using BPF_MEM instruction mode\n");
                 return -EACCES;
         }
 
         /* We only allow loading referenced kptr, since it will be marked as
          * untrusted, similar to unreferenced kptr.
          */
         if (class != BPF_LDX &&
             (kptr_field->type == BPF_KPTR_REF || kptr_field->type == BPF_KPTR_PERCPU)) {
                 verbose(env, "store to referenced kptr disallowed\n");
                 return -EACCES;
         }
 
         if (class == BPF_LDX) {
                 val_reg = reg_state(env, value_regno);
                 /* We can simply mark the value_regno receiving the pointer
                  * value from map as PTR_TO_BTF_ID, with the correct type.
                  */
                 mark_btf_ld_reg(env, cur_regs(env), value_regno, PTR_TO_BTF_ID, kptr_field->kptr.btf,
                                 kptr_field->kptr.btf_id, btf_ld_kptr_type(env, kptr_field));
         } else if (class == BPF_STX) {
                 val_reg = reg_state(env, value_regno);
                 if (!register_is_null(val_reg) &&
                     map_kptr_match_type(env, kptr_field, val_reg, value_regno))
                         return -EACCES;
         } else if (class == BPF_ST) {
                 if (insn->imm) {
                         verbose(env, "BPF_ST imm must be 0 when storing to kptr at off=%u\n",
                                 kptr_field->offset);
                         return -EACCES;
                 }
         } else {
                 verbose(env, "kptr in map can only be accessed using BPF_LDX/BPF_STX/BPF_ST\n");
                 return -EACCES;
         }
         return 0;
 }
 
 /* check read/write into a map element with possible variable offset */
 static int check_map_access(struct bpf_verifier_env *env, u32 regno,
                             int off, int size, bool zero_size_allowed,
                             enum bpf_access_src src)
 {
         struct bpf_verifier_state *vstate = env->cur_state;
         struct bpf_func_state *state = vstate->frame[vstate->curframe];
         struct bpf_reg_state *reg = &state->regs[regno];
         struct bpf_map *map = reg->map_ptr;
         struct btf_record *rec;
         int err, i;
 
         err = check_mem_region_access(env, regno, off, size, map->value_size,
                                       zero_size_allowed);
         if (err)
                 return err;
 
         if (IS_ERR_OR_NULL(map->record))
                 return 0;
         rec = map->record;
         for (i = 0; i < rec->cnt; i++) {
                 struct btf_field *field = &rec->fields[i];
                 u32 p = field->offset;
 
                 /* If any part of a field  can be touched by load/store, reject
                  * this program. To check that [x1, x2) overlaps with [y1, y2),
                  * it is sufficient to check x1 < y2 && y1 < x2.
                  */
                 if (reg->smin_value + off < p + field->size &&
                     p < reg->umax_value + off + size) {
                         switch (field->type) {
                         case BPF_KPTR_UNREF:
                         case BPF_KPTR_REF:
                         case BPF_KPTR_PERCPU:
                                 if (src != ACCESS_DIRECT) {
                                         verbose(env, "kptr cannot be accessed indirectly by helper\n");
                                         return -EACCES;
                                 }
                                 if (!tnum_is_const(reg->var_off)) {
                                         verbose(env, "kptr access cannot have variable offset\n");
                                         return -EACCES;
                                 }
                                 if (p != off + reg->var_off.value) {
                                         verbose(env, "kptr access misaligned expected=%u off=%llu\n",
                                                 p, off + reg->var_off.value);
                                         return -EACCES;
                                 }
                                 if (size != bpf_size_to_bytes(BPF_DW)) {
                                         verbose(env, "kptr access size must be BPF_DW\n");
                                         return -EACCES;
                                 }
                                 break;
                         default:
                                 verbose(env, "%s cannot be accessed directly by load/store\n",
                                         btf_field_type_name(field->type));
                                 return -EACCES;
                         }
                 }
         }
         return 0;
 }
 
 #define MAX_PACKET_OFF 0xffff
 
 static bool may_access_direct_pkt_data(struct bpf_verifier_env *env,
                                        const struct bpf_call_arg_meta *meta,
                                        enum bpf_access_type t)
 {
         enum bpf_prog_type prog_type = resolve_prog_type(env->prog);
 
         switch (prog_type) {
         /* Program types only with direct read access go here! */
         case BPF_PROG_TYPE_LWT_IN:
         case BPF_PROG_TYPE_LWT_OUT:
         case BPF_PROG_TYPE_LWT_SEG6LOCAL:
         case BPF_PROG_TYPE_SK_REUSEPORT:
         case BPF_PROG_TYPE_FLOW_DISSECTOR:
         case BPF_PROG_TYPE_CGROUP_SKB:
                 if (t == BPF_WRITE)
                         return false;
                 fallthrough;
 
         /* Program types with direct read + write access go here! */
         case BPF_PROG_TYPE_SCHED_CLS:
         case BPF_PROG_TYPE_SCHED_ACT:
         case BPF_PROG_TYPE_XDP:
         case BPF_PROG_TYPE_LWT_XMIT:
         case BPF_PROG_TYPE_SK_SKB:
         case BPF_PROG_TYPE_SK_MSG:
                 if (meta)
                         return meta->pkt_access;
 
                 env->seen_direct_write = true;
                 return true;
 
         case BPF_PROG_TYPE_CGROUP_SOCKOPT:
                 if (t == BPF_WRITE)
                         env->seen_direct_write = true;
 
                 return true;
 
         default:
                 return false;
         }
 }
 
 static int check_packet_access(struct bpf_verifier_env *env, u32 regno, int off,
                                int size, bool zero_size_allowed)
 {
         struct bpf_reg_state *regs = cur_regs(env);
         struct bpf_reg_state *reg = &regs[regno];
         int err;
 
         /* We may have added a variable offset to the packet pointer; but any
          * reg->range we have comes after that.  We are only checking the fixed
          * offset.
          */
 
         /* We don't allow negative numbers, because we aren't tracking enough
          * detail to prove they're safe.
          */
         if (reg->smin_value < 0) {
                 verbose(env, "R%d min value is negative, either use unsigned index or do a if (index >=0) check.\n",
                         regno);
                 return -EACCES;
         }
 
         err = reg->range < 0 ? -EINVAL :
               __check_mem_access(env, regno, off, size, reg->range,
                                  zero_size_allowed);
         if (err) {
                 verbose(env, "R%d offset is outside of the packet\n", regno);
                 return err;
         }
 
         /* __check_mem_access has made sure "off + size - 1" is within u16.
          * reg->umax_value can't be bigger than MAX_PACKET_OFF which is 0xffff,
          * otherwise find_good_pkt_pointers would have refused to set range info
          * that __check_mem_access would have rejected this pkt access.
          * Therefore, "off + reg->umax_value + size - 1" won't overflow u32.
          */
         env->prog->aux->max_pkt_offset =
                 max_t(u32, env->prog->aux->max_pkt_offset,
                       off + reg->umax_value + size - 1);
 
         return err;
 }
 
 /* check access to 'struct bpf_context' fields.  Supports fixed offsets only */
 static int check_ctx_access(struct bpf_verifier_env *env, int insn_idx, int off, int size,
                             enum bpf_access_type t, enum bpf_reg_type *reg_type,
                             struct btf **btf, u32 *btf_id, bool *is_retval, bool is_ldsx)
 {
         struct bpf_insn_access_aux info = {
                 .reg_type = *reg_type,
                 .log = &env->log,
                 .is_retval = false,
                 .is_ldsx = is_ldsx,
         };
 
         if (env->ops->is_valid_access &&
             env->ops->is_valid_access(off, size, t, env->prog, &info)) {
                 /* A non zero info.ctx_field_size indicates that this field is a
                  * candidate for later verifier transformation to load the whole
                  * field and then apply a mask when accessed with a narrower
                  * access than actual ctx access size. A zero info.ctx_field_size
                  * will only allow for whole field access and rejects any other
                  * type of narrower access.
                  */
                 *reg_type = info.reg_type;
                 *is_retval = info.is_retval;
 
                 if (base_type(*reg_type) == PTR_TO_BTF_ID) {
                         *btf = info.btf;
                         *btf_id = info.btf_id;
                 } else {
                         env->insn_aux_data[insn_idx].ctx_field_size = info.ctx_field_size;
                 }
                 /* remember the offset of last byte accessed in ctx */
                 if (env->prog->aux->max_ctx_offset < off + size)
                         env->prog->aux->max_ctx_offset = off + size;
                 return 0;
         }
 
         verbose(env, "invalid bpf_context access off=%d size=%d\n", off, size);
         return -EACCES;
 }
 
 static int check_flow_keys_access(struct bpf_verifier_env *env, int off,
                                   int size)
 {
         if (size < 0 || off < 0 ||
             (u64)off + size > sizeof(struct bpf_flow_keys)) {
                 verbose(env, "invalid access to flow keys off=%d size=%d\n",
                         off, size);
                 return -EACCES;
         }
         return 0;
 }
 
 static int check_sock_access(struct bpf_verifier_env *env, int insn_idx,
                              u32 regno, int off, int size,
                              enum bpf_access_type t)
 {
         struct bpf_reg_state *regs = cur_regs(env);
         struct bpf_reg_state *reg = &regs[regno];
         struct bpf_insn_access_aux info = {};
         bool valid;
 
         if (reg->smin_value < 0) {
                 verbose(env, "R%d min value is negative, either use unsigned index or do a if (index >=0) check.\n",
                         regno);
                 return -EACCES;
         }
 
         switch (reg->type) {
         case PTR_TO_SOCK_COMMON:
                 valid = bpf_sock_common_is_valid_access(off, size, t, &info);
                 break;
         case PTR_TO_SOCKET:
                 valid = bpf_sock_is_valid_access(off, size, t, &info);
                 break;
         case PTR_TO_TCP_SOCK:
                 valid = bpf_tcp_sock_is_valid_access(off, size, t, &info);
                 break;
         case PTR_TO_XDP_SOCK:
                 valid = bpf_xdp_sock_is_valid_access(off, size, t, &info);
                 break;
         default:
                 valid = false;
         }
 
 
         if (valid) {
                 env->insn_aux_data[insn_idx].ctx_field_size =
                         info.ctx_field_size;
                 return 0;
         }
 
         verbose(env, "R%d invalid %s access off=%d size=%d\n",
                 regno, reg_type_str(env, reg->type), off, size);
 
         return -EACCES;
 }
 
 static bool is_pointer_value(struct bpf_verifier_env *env, int regno)
 {
         return __is_pointer_value(env->allow_ptr_leaks, reg_state(env, regno));
 }
 
 static bool is_ctx_reg(struct bpf_verifier_env *env, int regno)
 {
         const struct bpf_reg_state *reg = reg_state(env, regno);
 
         return reg->type == PTR_TO_CTX;
 }
 
 static bool is_sk_reg(struct bpf_verifier_env *env, int regno)
 {
         const struct bpf_reg_state *reg = reg_state(env, regno);
 
         return type_is_sk_pointer(reg->type);
 }
 
 static bool is_pkt_reg(struct bpf_verifier_env *env, int regno)
 {
         const struct bpf_reg_state *reg = reg_state(env, regno);
 
         return type_is_pkt_pointer(reg->type);
 }
 
 static bool is_flow_key_reg(struct bpf_verifier_env *env, int regno)
 {
         const struct bpf_reg_state *reg = reg_state(env, regno);
 
         /* Separate to is_ctx_reg() since we still want to allow BPF_ST here. */
         return reg->type == PTR_TO_FLOW_KEYS;
 }
 
 static bool is_arena_reg(struct bpf_verifier_env *env, int regno)
 {
         const struct bpf_reg_state *reg = reg_state(env, regno);
 
         return reg->type == PTR_TO_ARENA;
 }
 
 static u32 *reg2btf_ids[__BPF_REG_TYPE_MAX] = {
 #ifdef CONFIG_NET
         [PTR_TO_SOCKET] = &btf_sock_ids[BTF_SOCK_TYPE_SOCK],
         [PTR_TO_SOCK_COMMON] = &btf_sock_ids[BTF_SOCK_TYPE_SOCK_COMMON],
         [PTR_TO_TCP_SOCK] = &btf_sock_ids[BTF_SOCK_TYPE_TCP],
 #endif
         [CONST_PTR_TO_MAP] = btf_bpf_map_id,
 };
 
 static bool is_trusted_reg(const struct bpf_reg_state *reg)
 {
         /* A referenced register is always trusted. */
         if (reg->ref_obj_id)
                 return true;
 
         /* Types listed in the reg2btf_ids are always trusted */
         if (reg2btf_ids[base_type(reg->type)] &&
             !bpf_type_has_unsafe_modifiers(reg->type))
                 return true;
 
         /* If a register is not referenced, it is trusted if it has the
          * MEM_ALLOC or PTR_TRUSTED type modifiers, and no others. Some of the
          * other type modifiers may be safe, but we elect to take an opt-in
          * approach here as some (e.g. PTR_UNTRUSTED and PTR_MAYBE_NULL) are
          * not.
          *
          * Eventually, we should make PTR_TRUSTED the single source of truth
          * for whether a register is trusted.
          */
         return type_flag(reg->type) & BPF_REG_TRUSTED_MODIFIERS &&
                !bpf_type_has_unsafe_modifiers(reg->type);
 }
 
 static bool is_rcu_reg(const struct bpf_reg_state *reg)
 {
         return reg->type & MEM_RCU;
 }
 
 static void clear_trusted_flags(enum bpf_type_flag *flag)
 {
         *flag &= ~(BPF_REG_TRUSTED_MODIFIERS | MEM_RCU);
 }
 
 static int check_pkt_ptr_alignment(struct bpf_verifier_env *env,
                                    const struct bpf_reg_state *reg,
                                    int off, int size, bool strict)
 {
         struct tnum reg_off;
         int ip_align;
 
         /* Byte size accesses are always allowed. */
         if (!strict || size == 1)
                 return 0;
 
         /* For platforms that do not have a Kconfig enabling
          * CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS the value of
          * NET_IP_ALIGN is universally set to '2'.  And on platforms
          * that do set CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS, we get
          * to this code only in strict mode where we want to emulate
          * the NET_IP_ALIGN==2 checking.  Therefore use an
          * unconditional IP align value of '2'.
          */
         ip_align = 2;
 
         reg_off = tnum_add(reg->var_off, tnum_const(ip_align + reg->off + off));
         if (!tnum_is_aligned(reg_off, size)) {
                 char tn_buf[48];
 
                 tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
                 verbose(env,
                         "misaligned packet access off %d+%s+%d+%d size %d\n",
                         ip_align, tn_buf, reg->off, off, size);
                 return -EACCES;
         }
 
         return 0;
 }
 
 static int check_generic_ptr_alignment(struct bpf_verifier_env *env,
                                        const struct bpf_reg_state *reg,
                                        const char *pointer_desc,
                                        int off, int size, bool strict)
 {
         struct tnum reg_off;
 
         /* Byte size accesses are always allowed. */
         if (!strict || size == 1)
                 return 0;
 
         reg_off = tnum_add(reg->var_off, tnum_const(reg->off + off));
         if (!tnum_is_aligned(reg_off, size)) {
                 char tn_buf[48];
 
                 tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
                 verbose(env, "misaligned %saccess off %s+%d+%d size %d\n",
                         pointer_desc, tn_buf, reg->off, off, size);
                 return -EACCES;
         }
 
         return 0;
 }
 
 static int check_ptr_alignment(struct bpf_verifier_env *env,
                                const struct bpf_reg_state *reg, int off,
                                int size, bool strict_alignment_once)
 {
         bool strict = env->strict_alignment || strict_alignment_once;
         const char *pointer_desc = "";
 
         switch (reg->type) {
         case PTR_TO_PACKET:
         case PTR_TO_PACKET_META:
                 /* Special case, because of NET_IP_ALIGN. Given metadata sits
                  * right in front, treat it the very same way.
                  */
                 return check_pkt_ptr_alignment(env, reg, off, size, strict);
         case PTR_TO_FLOW_KEYS:
                 pointer_desc = "flow keys ";
                 break;
         case PTR_TO_MAP_KEY:
                 pointer_desc = "key ";
                 break;
         case PTR_TO_MAP_VALUE:
                 pointer_desc = "value ";
                 break;
         case PTR_TO_CTX:
                 pointer_desc = "context ";
                 break;
         case PTR_TO_STACK:
                 pointer_desc = "stack ";
                 /* The stack spill tracking logic in check_stack_write_fixed_off()
                  * and check_stack_read_fixed_off() relies on stack accesses being
                  * aligned.
                  */
                 strict = true;
                 break;
         case PTR_TO_SOCKET:
                 pointer_desc = "sock ";
                 break;
         case PTR_TO_SOCK_COMMON:
                 pointer_desc = "sock_common ";
                 break;
         case PTR_TO_TCP_SOCK:
                 pointer_desc = "tcp_sock ";
                 break;
         case PTR_TO_XDP_SOCK:
                 pointer_desc = "xdp_sock ";
                 break;
         case PTR_TO_ARENA:
                 return 0;
         default:
                 break;
         }
         return check_generic_ptr_alignment(env, reg, pointer_desc, off, size,
                                            strict);
 }
 
 static int round_up_stack_depth(struct bpf_verifier_env *env, int stack_depth)
 {
         if (env->prog->jit_requested)
                 return round_up(stack_depth, 16);
 
         /* round up to 32-bytes, since this is granularity
          * of interpreter stack size
          */
         return round_up(max_t(u32, stack_depth, 1), 32);
 }
 
 /* starting from main bpf function walk all instructions of the function
  * and recursively walk all callees that given function can call.
  * Ignore jump and exit insns.
  * Since recursion is prevented by check_cfg() this algorithm
  * only needs a local stack of MAX_CALL_FRAMES to remember callsites
  */
 static int check_max_stack_depth_subprog(struct bpf_verifier_env *env, int idx)
 {
         struct bpf_subprog_info *subprog = env->subprog_info;
         struct bpf_insn *insn = env->prog->insnsi;
         int depth = 0, frame = 0, i, subprog_end;
         bool tail_call_reachable = false;
         int ret_insn[MAX_CALL_FRAMES];
         int ret_prog[MAX_CALL_FRAMES];
         int j;
 
         i = subprog[idx].start;
 process_func:
         /* protect against potential stack overflow that might happen when
          * bpf2bpf calls get combined with tailcalls. Limit the caller's stack
          * depth for such case down to 256 so that the worst case scenario
          * would result in 8k stack size (32 which is tailcall limit * 256 =
          * 8k).
          *
          * To get the idea what might happen, see an example:
          * func1 -> sub rsp, 128
          *  subfunc1 -> sub rsp, 256
          *  tailcall1 -> add rsp, 256
          *   func2 -> sub rsp, 192 (total stack size = 128 + 192 = 320)
          *   subfunc2 -> sub rsp, 64
          *   subfunc22 -> sub rsp, 128
          *   tailcall2 -> add rsp, 128
          *    func3 -> sub rsp, 32 (total stack size 128 + 192 + 64 + 32 = 416)
          *
          * tailcall will unwind the current stack frame but it will not get rid
          * of caller's stack as shown on the example above.
          */
         if (idx && subprog[idx].has_tail_call && depth >= 256) {
                 verbose(env,
                         "tail_calls are not allowed when call stack of previous frames is %d bytes. Too large\n",
                         depth);
                 return -EACCES;
         }
         depth += round_up_stack_depth(env, subprog[idx].stack_depth);
         if (depth > MAX_BPF_STACK) {
                 verbose(env, "combined stack size of %d calls is %d. Too large\n",
                         frame + 1, depth);
                 return -EACCES;
         }
 continue_func:
         subprog_end = subprog[idx + 1].start;
         for (; i < subprog_end; i++) {
                 int next_insn, sidx;
 
                 if (bpf_pseudo_kfunc_call(insn + i) && !insn[i].off) {
                         bool err = false;
 
                         if (!is_bpf_throw_kfunc(insn + i))
                                 continue;
                         if (subprog[idx].is_cb)
                                 err = true;
                         for (int c = 0; c < frame && !err; c++) {
                                 if (subprog[ret_prog[c]].is_cb) {
                                         err = true;
                                         break;
                                 }
                         }
                         if (!err)
                                 continue;
                         verbose(env,
                                 "bpf_throw kfunc (insn %d) cannot be called from callback subprog %d\n",
                                 i, idx);
                         return -EINVAL;
                 }
 
                 if (!bpf_pseudo_call(insn + i) && !bpf_pseudo_func(insn + i))
                         continue;
                 /* remember insn and function to return to */
                 ret_insn[frame] = i + 1;
                 ret_prog[frame] = idx;
 
                 /* find the callee */
                 next_insn = i + insn[i].imm + 1;
                 sidx = find_subprog(env, next_insn);
                 if (sidx < 0) {
                         WARN_ONCE(1, "verifier bug. No program starts at insn %d\n",
                                   next_insn);
                         return -EFAULT;
                 }
                 if (subprog[sidx].is_async_cb) {
                         if (subprog[sidx].has_tail_call) {
                                 verbose(env, "verifier bug. subprog has tail_call and async cb\n");
                                 return -EFAULT;
                         }
                         /* async callbacks don't increase bpf prog stack size unless called directly */
                         if (!bpf_pseudo_call(insn + i))
                                 continue;
                         if (subprog[sidx].is_exception_cb) {
                                 verbose(env, "insn %d cannot call exception cb directly\n", i);
                                 return -EINVAL;
                         }
                 }
                 i = next_insn;
                 idx = sidx;
 
                 if (subprog[idx].has_tail_call)
                         tail_call_reachable = true;
 
                 frame++;
                 if (frame >= MAX_CALL_FRAMES) {
                         verbose(env, "the call stack of %d frames is too deep !\n",
                                 frame);
                         return -E2BIG;
                 }
                 goto process_func;
         }
         /* if tail call got detected across bpf2bpf calls then mark each of the
          * currently present subprog frames as tail call reachable subprogs;
          * this info will be utilized by JIT so that we will be preserving the
          * tail call counter throughout bpf2bpf calls combined with tailcalls
          */
         if (tail_call_reachable)
                 for (j = 0; j < frame; j++) {
                         if (subprog[ret_prog[j]].is_exception_cb) {
                                 verbose(env, "cannot tail call within exception cb\n");
                                 return -EINVAL;
                         }
                         subprog[ret_prog[j]].tail_call_reachable = true;
                 }
         if (subprog[0].tail_call_reachable)
                 env->prog->aux->tail_call_reachable = true;
 
         /* end of for() loop means the last insn of the 'subprog'
          * was reached. Doesn't matter whether it was JA or EXIT
          */
         if (frame == 0)
                 return 0;
         depth -= round_up_stack_depth(env, subprog[idx].stack_depth);
         frame--;
         i = ret_insn[frame];
         idx = ret_prog[frame];
         goto continue_func;
 }
 
 static int check_max_stack_depth(struct bpf_verifier_env *env)
 {
         struct bpf_subprog_info *si = env->subprog_info;
         int ret;
 
         for (int i = 0; i < env->subprog_cnt; i++) {
                 if (!i || si[i].is_async_cb) {
                         ret = check_max_stack_depth_subprog(env, i);
                         if (ret < 0)
                                 return ret;
                 }
                 continue;
         }
         return 0;
 }
 
 #ifndef CONFIG_BPF_JIT_ALWAYS_ON
 static int get_callee_stack_depth(struct bpf_verifier_env *env,
                                   const struct bpf_insn *insn, int idx)
 {
         int start = idx + insn->imm + 1, subprog;
 
         subprog = find_subprog(env, start);
         if (subprog < 0) {
                 WARN_ONCE(1, "verifier bug. No program starts at insn %d\n",
                           start);
                 return -EFAULT;
         }
         return env->subprog_info[subprog].stack_depth;
 }
 #endif
 
 static int __check_buffer_access(struct bpf_verifier_env *env,
                                  const char *buf_info,
                                  const struct bpf_reg_state *reg,
                                  int regno, int off, int size)
 {
         if (off < 0) {
                 verbose(env,
                         "R%d invalid %s buffer access: off=%d, size=%d\n",
                         regno, buf_info, off, size);
                 return -EACCES;
         }
         if (!tnum_is_const(reg->var_off) || reg->var_off.value) {
                 char tn_buf[48];
 
                 tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
                 verbose(env,
                         "R%d invalid variable buffer offset: off=%d, var_off=%s\n",
                         regno, off, tn_buf);
                 return -EACCES;
         }
 
         return 0;
 }
 
 static int check_tp_buffer_access(struct bpf_verifier_env *env,
                                   const struct bpf_reg_state *reg,
                                   int regno, int off, int size)
 {
         int err;
 
         err = __check_buffer_access(env, "tracepoint", reg, regno, off, size);
         if (err)
                 return err;
 
         if (off + size > env->prog->aux->max_tp_access)
                 env->prog->aux->max_tp_access = off + size;
 
         return 0;
 }
 
 static int check_buffer_access(struct bpf_verifier_env *env,
                                const struct bpf_reg_state *reg,
                                int regno, int off, int size,
                                bool zero_size_allowed,
                                u32 *max_access)
 {
         const char *buf_info = type_is_rdonly_mem(reg->type) ? "rdonly" : "rdwr";
         int err;
 
         err = __check_buffer_access(env, buf_info, reg, regno, off, size);
         if (err)
                 return err;
 
         if (off + size > *max_access)
                 *max_access = off + size;
 
         return 0;
 }
 
 /* BPF architecture zero extends alu32 ops into 64-bit registesr */
 static void zext_32_to_64(struct bpf_reg_state *reg)
 {
         reg->var_off = tnum_subreg(reg->var_off);
         __reg_assign_32_into_64(reg);
 }
 
 /* truncate register to smaller size (in bytes)
  * must be called with size < BPF_REG_SIZE
  */
 static void coerce_reg_to_size(struct bpf_reg_state *reg, int size)
 {
         u64 mask;
 
         /* clear high bits in bit representation */
         reg->var_off = tnum_cast(reg->var_off, size);
 
         /* fix arithmetic bounds */
         mask = ((u64)1 << (size * 8)) - 1;
         if ((reg->umin_value & ~mask) == (reg->umax_value & ~mask)) {
                 reg->umin_value &= mask;
                 reg->umax_value &= mask;
         } else {
                 reg->umin_value = 0;
                 reg->umax_value = mask;
         }
         reg->smin_value = reg->umin_value;
         reg->smax_value = reg->umax_value;
 
         /* If size is smaller than 32bit register the 32bit register
          * values are also truncated so we push 64-bit bounds into
          * 32-bit bounds. Above were truncated < 32-bits already.
          */
         if (size < 4)
                 __mark_reg32_unbounded(reg);
 
         reg_bounds_sync(reg);
 }
 
 static void set_sext64_default_val(struct bpf_reg_state *reg, int size)
 {
         if (size == 1) {
                 reg->smin_value = reg->s32_min_value = S8_MIN;
                 reg->smax_value = reg->s32_max_value = S8_MAX;
         } else if (size == 2) {
                 reg->smin_value = reg->s32_min_value = S16_MIN;
                 reg->smax_value = reg->s32_max_value = S16_MAX;
         } else {
                 /* size == 4 */
                 reg->smin_value = reg->s32_min_value = S32_MIN;
                 reg->smax_value = reg->s32_max_value = S32_MAX;
         }
         reg->umin_value = reg->u32_min_value = 0;
         reg->umax_value = U64_MAX;
         reg->u32_max_value = U32_MAX;
         reg->var_off = tnum_unknown;
 }
 
 static void coerce_reg_to_size_sx(struct bpf_reg_state *reg, int size)
 {
         s64 init_s64_max, init_s64_min, s64_max, s64_min, u64_cval;
         u64 top_smax_value, top_smin_value;
         u64 num_bits = size * 8;
 
         if (tnum_is_const(reg->var_off)) {
                 u64_cval = reg->var_off.value;
                 if (size == 1)
                         reg->var_off = tnum_const((s8)u64_cval);
                 else if (size == 2)
                         reg->var_off = tnum_const((s16)u64_cval);
                 else
                         /* size == 4 */
                         reg->var_off = tnum_const((s32)u64_cval);
 
                 u64_cval = reg->var_off.value;
                 reg->smax_value = reg->smin_value = u64_cval;
                 reg->umax_value = reg->umin_value = u64_cval;
                 reg->s32_max_value = reg->s32_min_value = u64_cval;
                 reg->u32_max_value = reg->u32_min_value = u64_cval;
                 return;
         }
 
         top_smax_value = ((u64)reg->smax_value >> num_bits) << num_bits;
         top_smin_value = ((u64)reg->smin_value >> num_bits) << num_bits;
 
         if (top_smax_value != top_smin_value)
                 goto out;
 
         /* find the s64_min and s64_min after sign extension */
         if (size == 1) {
                 init_s64_max = (s8)reg->smax_value;
                 init_s64_min = (s8)reg->smin_value;
         } else if (size == 2) {
                 init_s64_max = (s16)reg->smax_value;
                 init_s64_min = (s16)reg->smin_value;
         } else {
                 init_s64_max = (s32)reg->smax_value;
                 init_s64_min = (s32)reg->smin_value;
         }
 
         s64_max = max(init_s64_max, init_s64_min);
         s64_min = min(init_s64_max, init_s64_min);
 
         /* both of s64_max/s64_min positive or negative */
         if ((s64_max >= 0) == (s64_min >= 0)) {
                 reg->smin_value = reg->s32_min_value = s64_min;
                 reg->smax_value = reg->s32_max_value = s64_max;
                 reg->umin_value = reg->u32_min_value = s64_min;
                 reg->umax_value = reg->u32_max_value = s64_max;
                 reg->var_off = tnum_range(s64_min, s64_max);
                 return;
         }
 
 out:
         set_sext64_default_val(reg, size);
 }
 
 static void set_sext32_default_val(struct bpf_reg_state *reg, int size)
 {
         if (size == 1) {
                 reg->s32_min_value = S8_MIN;
                 reg->s32_max_value = S8_MAX;
         } else {
                 /* size == 2 */
                 reg->s32_min_value = S16_MIN;
                 reg->s32_max_value = S16_MAX;
         }
         reg->u32_min_value = 0;
         reg->u32_max_value = U32_MAX;
         reg->var_off = tnum_subreg(tnum_unknown);
 }
 
 static void coerce_subreg_to_size_sx(struct bpf_reg_state *reg, int size)
 {
         s32 init_s32_max, init_s32_min, s32_max, s32_min, u32_val;
         u32 top_smax_value, top_smin_value;
         u32 num_bits = size * 8;
 
         if (tnum_is_const(reg->var_off)) {
                 u32_val = reg->var_off.value;
                 if (size == 1)
                         reg->var_off = tnum_const((s8)u32_val);
                 else
                         reg->var_off = tnum_const((s16)u32_val);
 
                 u32_val = reg->var_off.value;
                 reg->s32_min_value = reg->s32_max_value = u32_val;
                 reg->u32_min_value = reg->u32_max_value = u32_val;
                 return;
         }
 
         top_smax_value = ((u32)reg->s32_max_value >> num_bits) << num_bits;
         top_smin_value = ((u32)reg->s32_min_value >> num_bits) << num_bits;
 
         if (top_smax_value != top_smin_value)
                 goto out;
 
         /* find the s32_min and s32_min after sign extension */
         if (size == 1) {
                 init_s32_max = (s8)reg->s32_max_value;
                 init_s32_min = (s8)reg->s32_min_value;
         } else {
                 /* size == 2 */
                 init_s32_max = (s16)reg->s32_max_value;
                 init_s32_min = (s16)reg->s32_min_value;
         }
         s32_max = max(init_s32_max, init_s32_min);
         s32_min = min(init_s32_max, init_s32_min);
 
         if ((s32_min >= 0) == (s32_max >= 0)) {
                 reg->s32_min_value = s32_min;
                 reg->s32_max_value = s32_max;
                 reg->u32_min_value = (u32)s32_min;
                 reg->u32_max_value = (u32)s32_max;
                 reg->var_off = tnum_subreg(tnum_range(s32_min, s32_max));
                 return;
         }
 
 out:
         set_sext32_default_val(reg, size);
 }
 
 static bool bpf_map_is_rdonly(const struct bpf_map *map)
 {
         /* A map is considered read-only if the following condition are true:
          *
          * 1) BPF program side cannot change any of the map content. The
          *    BPF_F_RDONLY_PROG flag is throughout the lifetime of a map
          *    and was set at map creation time.
          * 2) The map value(s) have been initialized from user space by a
          *    loader and then "frozen", such that no new map update/delete
          *    operations from syscall side are possible for the rest of
          *    the map's lifetime from that point onwards.
          * 3) Any parallel/pending map update/delete operations from syscall
          *    side have been completed. Only after that point, it's safe to
          *    assume that map value(s) are immutable.
          */
         return (map->map_flags & BPF_F_RDONLY_PROG) &&
                READ_ONCE(map->frozen) &&
                !bpf_map_write_active(map);
 }
 
 static int bpf_map_direct_read(struct bpf_map *map, int off, int size, u64 *val,
                                bool is_ldsx)
 {
         void *ptr;
         u64 addr;
         int err;
 
         err = map->ops->map_direct_value_addr(map, &addr, off);
         if (err)
                 return err;
         ptr = (void *)(long)addr + off;
 
         switch (size) {
         case sizeof(u8):
                 *val = is_ldsx ? (s64)*(s8 *)ptr : (u64)*(u8 *)ptr;
                 break;
         case sizeof(u16):
                 *val = is_ldsx ? (s64)*(s16 *)ptr : (u64)*(u16 *)ptr;
                 break;
         case sizeof(u32):
                 *val = is_ldsx ? (s64)*(s32 *)ptr : (u64)*(u32 *)ptr;
                 break;
         case sizeof(u64):
                 *val = *(u64 *)ptr;
                 break;
         default:
                 return -EINVAL;
         }
         return 0;
 }
 
 #define BTF_TYPE_SAFE_RCU(__type)  __PASTE(__type, __safe_rcu)
 #define BTF_TYPE_SAFE_RCU_OR_NULL(__type)  __PASTE(__type, __safe_rcu_or_null)
 #define BTF_TYPE_SAFE_TRUSTED(__type)  __PASTE(__type, __safe_trusted)
 #define BTF_TYPE_SAFE_TRUSTED_OR_NULL(__type)  __PASTE(__type, __safe_trusted_or_null)
 
 /*
  * Allow list few fields as RCU trusted or full trusted.
  * This logic doesn't allow mix tagging and will be removed once GCC supports
  * btf_type_tag.
  */
 
 /* RCU trusted: these fields are trusted in RCU CS and never NULL */
 BTF_TYPE_SAFE_RCU(struct task_struct) {
         const cpumask_t *cpus_ptr;
         struct css_set __rcu *cgroups;
         struct task_struct __rcu *real_parent;
         struct task_struct *group_leader;
 };
 
 BTF_TYPE_SAFE_RCU(struct cgroup) {
         /* cgrp->kn is always accessible as documented in kernel/cgroup/cgroup.c */
         struct kernfs_node *kn;
 };
 
 BTF_TYPE_SAFE_RCU(struct css_set) {
         struct cgroup *dfl_cgrp;
 };
 
 /* RCU trusted: these fields are trusted in RCU CS and can be NULL */
 BTF_TYPE_SAFE_RCU_OR_NULL(struct mm_struct) {
         struct file __rcu *exe_file;
 };
 
 /* skb->sk, req->sk are not RCU protected, but we mark them as such
  * because bpf prog accessible sockets are SOCK_RCU_FREE.
  */
 BTF_TYPE_SAFE_RCU_OR_NULL(struct sk_buff) {
         struct sock *sk;
 };
 
 BTF_TYPE_SAFE_RCU_OR_NULL(struct request_sock) {
         struct sock *sk;
 };
 
 /* full trusted: these fields are trusted even outside of RCU CS and never NULL */
 BTF_TYPE_SAFE_TRUSTED(struct bpf_iter_meta) {
         struct seq_file *seq;
 };
 
 BTF_TYPE_SAFE_TRUSTED(struct bpf_iter__task) {
         struct bpf_iter_meta *meta;
         struct task_struct *task;
 };
 
 BTF_TYPE_SAFE_TRUSTED(struct linux_binprm) {
         struct file *file;
 };
 
 BTF_TYPE_SAFE_TRUSTED(struct file) {
         struct inode *f_inode;
 };
 
 BTF_TYPE_SAFE_TRUSTED(struct dentry) {
         /* no negative dentry-s in places where bpf can see it */
         struct inode *d_inode;
 };
 
 BTF_TYPE_SAFE_TRUSTED_OR_NULL(struct socket) {
         struct sock *sk;
 };
 
 static bool type_is_rcu(struct bpf_verifier_env *env,
                         struct bpf_reg_state *reg,
                         const char *field_name, u32 btf_id)
 {
         BTF_TYPE_EMIT(BTF_TYPE_SAFE_RCU(struct task_struct));
         BTF_TYPE_EMIT(BTF_TYPE_SAFE_RCU(struct cgroup));
         BTF_TYPE_EMIT(BTF_TYPE_SAFE_RCU(struct css_set));
 
         return btf_nested_type_is_trusted(&env->log, reg, field_name, btf_id, "__safe_rcu");
 }
 
 static bool type_is_rcu_or_null(struct bpf_verifier_env *env,
                                 struct bpf_reg_state *reg,
                                 const char *field_name, u32 btf_id)
 {
         BTF_TYPE_EMIT(BTF_TYPE_SAFE_RCU_OR_NULL(struct mm_struct));
         BTF_TYPE_EMIT(BTF_TYPE_SAFE_RCU_OR_NULL(struct sk_buff));
         BTF_TYPE_EMIT(BTF_TYPE_SAFE_RCU_OR_NULL(struct request_sock));
 
         return btf_nested_type_is_trusted(&env->log, reg, field_name, btf_id, "__safe_rcu_or_null");
 }
 
 static bool type_is_trusted(struct bpf_verifier_env *env,
                             struct bpf_reg_state *reg,
                             const char *field_name, u32 btf_id)
 {
         BTF_TYPE_EMIT(BTF_TYPE_SAFE_TRUSTED(struct bpf_iter_meta));
         BTF_TYPE_EMIT(BTF_TYPE_SAFE_TRUSTED(struct bpf_iter__task));
         BTF_TYPE_EMIT(BTF_TYPE_SAFE_TRUSTED(struct linux_binprm));
         BTF_TYPE_EMIT(BTF_TYPE_SAFE_TRUSTED(struct file));
         BTF_TYPE_EMIT(BTF_TYPE_SAFE_TRUSTED(struct dentry));
 
         return btf_nested_type_is_trusted(&env->log, reg, field_name, btf_id, "__safe_trusted");
 }
 
 static bool type_is_trusted_or_null(struct bpf_verifier_env *env,
                                     struct bpf_reg_state *reg,
                                     const char *field_name, u32 btf_id)
 {
         BTF_TYPE_EMIT(BTF_TYPE_SAFE_TRUSTED_OR_NULL(struct socket));
 
         return btf_nested_type_is_trusted(&env->log, reg, field_name, btf_id,
                                           "__safe_trusted_or_null");
 }
 
 static int check_ptr_to_btf_access(struct bpf_verifier_env *env,
                                    struct bpf_reg_state *regs,
                                    int regno, int off, int size,
                                    enum bpf_access_type atype,
                                    int value_regno)
 {
         struct bpf_reg_state *reg = regs + regno;
         const struct btf_type *t = btf_type_by_id(reg->btf, reg->btf_id);
         const char *tname = btf_name_by_offset(reg->btf, t->name_off);
         const char *field_name = NULL;
         enum bpf_type_flag flag = 0;
         u32 btf_id = 0;
         int ret;
 
         if (!env->allow_ptr_leaks) {
                 verbose(env,
                         "'struct %s' access is allowed only to CAP_PERFMON and CAP_SYS_ADMIN\n",
                         tname);
                 return -EPERM;
         }
         if (!env->prog->gpl_compatible && btf_is_kernel(reg->btf)) {
                 verbose(env,
                         "Cannot access kernel 'struct %s' from non-GPL compatible program\n",
                         tname);
                 return -EINVAL;
         }
         if (off < 0) {
                 verbose(env,
                         "R%d is ptr_%s invalid negative access: off=%d\n",
                         regno, tname, off);
                 return -EACCES;
         }
         if (!tnum_is_const(reg->var_off) || reg->var_off.value) {
                 char tn_buf[48];
 
                 tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
                 verbose(env,
                         "R%d is ptr_%s invalid variable offset: off=%d, var_off=%s\n",
                         regno, tname, off, tn_buf);
                 return -EACCES;
         }
 
         if (reg->type & MEM_USER) {
                 verbose(env,
                         "R%d is ptr_%s access user memory: off=%d\n",
                         regno, tname, off);
                 return -EACCES;
         }
 
         if (reg->type & MEM_PERCPU) {
                 verbose(env,
                         "R%d is ptr_%s access percpu memory: off=%d\n",
                         regno, tname, off);
                 return -EACCES;
         }
 
         if (env->ops->btf_struct_access && !type_is_alloc(reg->type) && atype == BPF_WRITE) {
                 if (!btf_is_kernel(reg->btf)) {
                         verbose(env, "verifier internal error: reg->btf must be kernel btf\n");
                         return -EFAULT;
                 }
                 ret = env->ops->btf_struct_access(&env->log, reg, off, size);
         } else {
                 /* Writes are permitted with default btf_struct_access for
                  * program allocated objects (which always have ref_obj_id > 0),
                  * but not for untrusted PTR_TO_BTF_ID | MEM_ALLOC.
                  */
                 if (atype != BPF_READ && !type_is_ptr_alloc_obj(reg->type)) {
                         verbose(env, "only read is supported\n");
                         return -EACCES;
                 }
 
                 if (type_is_alloc(reg->type) && !type_is_non_owning_ref(reg->type) &&
                     !(reg->type & MEM_RCU) && !reg->ref_obj_id) {
                         verbose(env, "verifier internal error: ref_obj_id for allocated object must be non-zero\n");
                         return -EFAULT;
                 }
 
                 ret = btf_struct_access(&env->log, reg, off, size, atype, &btf_id, &flag, &field_name);
         }
 
         if (ret < 0)
                 return ret;
 
         if (ret != PTR_TO_BTF_ID) {
                 /* just mark; */
 
         } else if (type_flag(reg->type) & PTR_UNTRUSTED) {
                 /* If this is an untrusted pointer, all pointers formed by walking it
                  * also inherit the untrusted flag.
                  */
                 flag = PTR_UNTRUSTED;
 
         } else if (is_trusted_reg(reg) || is_rcu_reg(reg)) {
                 /* By default any pointer obtained from walking a trusted pointer is no
                  * longer trusted, unless the field being accessed has explicitly been
                  * marked as inheriting its parent's state of trust (either full or RCU).
                  * For example:
                  * 'cgroups' pointer is untrusted if task->cgroups dereference
                  * happened in a sleepable program outside of bpf_rcu_read_lock()
                  * section. In a non-sleepable program it's trusted while in RCU CS (aka MEM_RCU).
                  * Note bpf_rcu_read_unlock() converts MEM_RCU pointers to PTR_UNTRUSTED.
                  *
                  * A regular RCU-protected pointer with __rcu tag can also be deemed
                  * trusted if we are in an RCU CS. Such pointer can be NULL.
                  */
                 if (type_is_trusted(env, reg, field_name, btf_id)) {
                         flag |= PTR_TRUSTED;
                 } else if (type_is_trusted_or_null(env, reg, field_name, btf_id)) {
                         flag |= PTR_TRUSTED | PTR_MAYBE_NULL;
                 } else if (in_rcu_cs(env) && !type_may_be_null(reg->type)) {
                         if (type_is_rcu(env, reg, field_name, btf_id)) {
                                 /* ignore __rcu tag and mark it MEM_RCU */
                                 flag |= MEM_RCU;
                         } else if (flag & MEM_RCU ||
                                    type_is_rcu_or_null(env, reg, field_name, btf_id)) {
                                 /* __rcu tagged pointers can be NULL */
                                 flag |= MEM_RCU | PTR_MAYBE_NULL;
 
                                 /* We always trust them */
                                 if (type_is_rcu_or_null(env, reg, field_name, btf_id) &&
                                     flag & PTR_UNTRUSTED)
                                         flag &= ~PTR_UNTRUSTED;
                         } else if (flag & (MEM_PERCPU | MEM_USER)) {
                                 /* keep as-is */
                         } else {
                                 /* walking unknown pointers yields old deprecated PTR_TO_BTF_ID */
                                 clear_trusted_flags(&flag);
                         }
                 } else {
                         /*
                          * If not in RCU CS or MEM_RCU pointer can be NULL then
                          * aggressively mark as untrusted otherwise such
                          * pointers will be plain PTR_TO_BTF_ID without flags
                          * and will be allowed to be passed into helpers for
                          * compat reasons.
                          */
                         flag = PTR_UNTRUSTED;
                 }
         } else {
                 /* Old compat. Deprecated */
                 clear_trusted_flags(&flag);
         }
 
         if (atype == BPF_READ && value_regno >= 0)
                 mark_btf_ld_reg(env, regs, value_regno, ret, reg->btf, btf_id, flag);
 
         return 0;
 }
 
 static int check_ptr_to_map_access(struct bpf_verifier_env *env,
                                    struct bpf_reg_state *regs,
                                    int regno, int off, int size,
                                    enum bpf_access_type atype,
                                    int value_regno)
 {
         struct bpf_reg_state *reg = regs + regno;
         struct bpf_map *map = reg->map_ptr;
         struct bpf_reg_state map_reg;
         enum bpf_type_flag flag = 0;
         const struct btf_type *t;
         const char *tname;
         u32 btf_id;
         int ret;
 
         if (!btf_vmlinux) {
                 verbose(env, "map_ptr access not supported without CONFIG_DEBUG_INFO_BTF\n");
                 return -ENOTSUPP;
         }
 
         if (!map->ops->map_btf_id || !*map->ops->map_btf_id) {
                 verbose(env, "map_ptr access not supported for map type %d\n",
                         map->map_type);
                 return -ENOTSUPP;
         }
 
         t = btf_type_by_id(btf_vmlinux, *map->ops->map_btf_id);
         tname = btf_name_by_offset(btf_vmlinux, t->name_off);
 
         if (!env->allow_ptr_leaks) {
                 verbose(env,
                         "'struct %s' access is allowed only to CAP_PERFMON and CAP_SYS_ADMIN\n",
                         tname);
                 return -EPERM;
         }
 
         if (off < 0) {
                 verbose(env, "R%d is %s invalid negative access: off=%d\n",
                         regno, tname, off);
                 return -EACCES;
         }
 
         if (atype != BPF_READ) {
                 verbose(env, "only read from %s is supported\n", tname);
                 return -EACCES;
         }
 
         /* Simulate access to a PTR_TO_BTF_ID */
         memset(&map_reg, 0, sizeof(map_reg));
         mark_btf_ld_reg(env, &map_reg, 0, PTR_TO_BTF_ID, btf_vmlinux, *map->ops->map_btf_id, 0);
         ret = btf_struct_access(&env->log, &map_reg, off, size, atype, &btf_id, &flag, NULL);
         if (ret < 0)
                 return ret;
 
         if (value_regno >= 0)
                 mark_btf_ld_reg(env, regs, value_regno, ret, btf_vmlinux, btf_id, flag);
 
         return 0;
 }
 
 /* Check that the stack access at the given offset is within bounds. The
  * maximum valid offset is -1.
  *
  * The minimum valid offset is -MAX_BPF_STACK for writes, and
  * -state->allocated_stack for reads.
  */
 static int check_stack_slot_within_bounds(struct bpf_verifier_env *env,
                                           s64 off,
                                           struct bpf_func_state *state,
                                           enum bpf_access_type t)
 {
         int min_valid_off;
 
         if (t == BPF_WRITE || env->allow_uninit_stack)
                 min_valid_off = -MAX_BPF_STACK;
         else
                 min_valid_off = -state->allocated_stack;
 
         if (off < min_valid_off || off > -1)
                 return -EACCES;
         return 0;
 }
 
 /* Check that the stack access at 'regno + off' falls within the maximum stack
  * bounds.
  *
  * 'off' includes `regno->offset`, but not its dynamic part (if any).
  */
 static int check_stack_access_within_bounds(
                 struct bpf_verifier_env *env,
                 int regno, int off, int access_size,
                 enum bpf_access_src src, enum bpf_access_type type)
 {
         struct bpf_reg_state *regs = cur_regs(env);
         struct bpf_reg_state *reg = regs + regno;
         struct bpf_func_state *state = func(env, reg);
         s64 min_off, max_off;
         int err;
         char *err_extra;
 
         if (src == ACCESS_HELPER)
                 /* We don't know if helpers are reading or writing (or both). */
                 err_extra = " indirect access to";
         else if (type == BPF_READ)
                 err_extra = " read from";
         else
                 err_extra = " write to";
 
         if (tnum_is_const(reg->var_off)) {
                 min_off = (s64)reg->var_off.value + off;
                 max_off = min_off + access_size;
         } else {
                 if (reg->smax_value >= BPF_MAX_VAR_OFF ||
                     reg->smin_value <= -BPF_MAX_VAR_OFF) {
                         verbose(env, "invalid unbounded variable-offset%s stack R%d\n",
                                 err_extra, regno);
                         return -EACCES;
                 }
                 min_off = reg->smin_value + off;
                 max_off = reg->smax_value + off + access_size;
         }
 
         err = check_stack_slot_within_bounds(env, min_off, state, type);
         if (!err && max_off > 0)
                 err = -EINVAL; /* out of stack access into non-negative offsets */
         if (!err && access_size < 0)
                 /* access_size should not be negative (or overflow an int); others checks
                  * along the way should have prevented such an access.
                  */
                 err = -EFAULT; /* invalid negative access size; integer overflow? */
 
         if (err) {
                 if (tnum_is_const(reg->var_off)) {
                         verbose(env, "invalid%s stack R%d off=%d size=%d\n",
                                 err_extra, regno, off, access_size);
                 } else {
                         char tn_buf[48];
 
                         tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
                         verbose(env, "invalid variable-offset%s stack R%d var_off=%s off=%d size=%d\n",
                                 err_extra, regno, tn_buf, off, access_size);
                 }
                 return err;
         }
 
         /* Note that there is no stack access with offset zero, so the needed stack
          * size is -min_off, not -min_off+1.
          */
         return grow_stack_state(env, state, -min_off /* size */);
 }
 
 static bool get_func_retval_range(struct bpf_prog *prog,
                                   struct bpf_retval_range *range)
 {
         if (prog->type == BPF_PROG_TYPE_LSM &&
                 prog->expected_attach_type == BPF_LSM_MAC &&
                 !bpf_lsm_get_retval_range(prog, range)) {
                 return true;
         }
         return false;
 }
 
 /* check whether memory at (regno + off) is accessible for t = (read | write)
  * if t==write, value_regno is a register which value is stored into memory
  * if t==read, value_regno is a register which will receive the value from memory
  * if t==write && value_regno==-1, some unknown value is stored into memory
  * if t==read && value_regno==-1, don't care what we read from memory
  */
 static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, u32 regno,
                             int off, int bpf_size, enum bpf_access_type t,
                             int value_regno, bool strict_alignment_once, bool is_ldsx)
 {
         struct bpf_reg_state *regs = cur_regs(env);
         struct bpf_reg_state *reg = regs + regno;
         int size, err = 0;
 
         size = bpf_size_to_bytes(bpf_size);
         if (size < 0)
                 return size;
 
         /* alignment checks will add in reg->off themselves */
         err = check_ptr_alignment(env, reg, off, size, strict_alignment_once);
         if (err)
                 return err;
 
         /* for access checks, reg->off is just part of off */
         off += reg->off;
 
         if (reg->type == PTR_TO_MAP_KEY) {
                 if (t == BPF_WRITE) {
                         verbose(env, "write to change key R%d not allowed\n", regno);
                         return -EACCES;
                 }
 
                 err = check_mem_region_access(env, regno, off, size,
                                               reg->map_ptr->key_size, false);
                 if (err)
                         return err;
                 if (value_regno >= 0)
                         mark_reg_unknown(env, regs, value_regno);
         } else if (reg->type == PTR_TO_MAP_VALUE) {
                 struct btf_field *kptr_field = NULL;
 
                 if (t == BPF_WRITE && value_regno >= 0 &&
                     is_pointer_value(env, value_regno)) {
                         verbose(env, "R%d leaks addr into map\n", value_regno);
                         return -EACCES;
                 }
                 err = check_map_access_type(env, regno, off, size, t);
                 if (err)
                         return err;
                 err = check_map_access(env, regno, off, size, false, ACCESS_DIRECT);
                 if (err)
                         return err;
                 if (tnum_is_const(reg->var_off))
                         kptr_field = btf_record_find(reg->map_ptr->record,
                                                      off + reg->var_off.value, BPF_KPTR);
                 if (kptr_field) {
                         err = check_map_kptr_access(env, regno, value_regno, insn_idx, kptr_field);
                 } else if (t == BPF_READ && value_regno >= 0) {
                         struct bpf_map *map = reg->map_ptr;
 
                         /* if map is read-only, track its contents as scalars */
                         if (tnum_is_const(reg->var_off) &&
                             bpf_map_is_rdonly(map) &&
                             map->ops->map_direct_value_addr) {
                                 int map_off = off + reg->var_off.value;
                                 u64 val = 0;
 
                                 err = bpf_map_direct_read(map, map_off, size,
                                                           &val, is_ldsx);
                                 if (err)
                                         return err;
 
                                 regs[value_regno].type = SCALAR_VALUE;
                                 __mark_reg_known(&regs[value_regno], val);
                         } else {
                                 mark_reg_unknown(env, regs, value_regno);
                         }
                 }
         } else if (base_type(reg->type) == PTR_TO_MEM) {
                 bool rdonly_mem = type_is_rdonly_mem(reg->type);
 
                 if (type_may_be_null(reg->type)) {
                         verbose(env, "R%d invalid mem access '%s'\n", regno,
                                 reg_type_str(env, reg->type));
                         return -EACCES;
                 }
 
                 if (t == BPF_WRITE && rdonly_mem) {
                         verbose(env, "R%d cannot write into %s\n",
                                 regno, reg_type_str(env, reg->type));
                         return -EACCES;
                 }
 
                 if (t == BPF_WRITE && value_regno >= 0 &&
                     is_pointer_value(env, value_regno)) {
                         verbose(env, "R%d leaks addr into mem\n", value_regno);
                         return -EACCES;
                 }
 
                 err = check_mem_region_access(env, regno, off, size,
                                               reg->mem_size, false);
                 if (!err && value_regno >= 0 && (t == BPF_READ || rdonly_mem))
                         mark_reg_unknown(env, regs, value_regno);
         } else if (reg->type == PTR_TO_CTX) {
                 bool is_retval = false;
                 struct bpf_retval_range range;
                 enum bpf_reg_type reg_type = SCALAR_VALUE;
                 struct btf *btf = NULL;
                 u32 btf_id = 0;
 
                 if (t == BPF_WRITE && value_regno >= 0 &&
                     is_pointer_value(env, value_regno)) {
                         verbose(env, "R%d leaks addr into ctx\n", value_regno);
                         return -EACCES;
                 }
 
                 err = check_ptr_off_reg(env, reg, regno);
                 if (err < 0)
                         return err;
 
                 err = check_ctx_access(env, insn_idx, off, size, t, &reg_type, &btf,
                                        &btf_id, &is_retval, is_ldsx);
                 if (err)
                         verbose_linfo(env, insn_idx, "; ");
                 if (!err && t == BPF_READ && value_regno >= 0) {
                         /* ctx access returns either a scalar, or a
                          * PTR_TO_PACKET[_META,_END]. In the latter
                          * case, we know the offset is zero.
                          */
                         if (reg_type == SCALAR_VALUE) {
                                 if (is_retval && get_func_retval_range(env->prog, &range)) {
                                         err = __mark_reg_s32_range(env, regs, value_regno,
                                                                    range.minval, range.maxval);
                                         if (err)
                                                 return err;
                                 } else {
                                         mark_reg_unknown(env, regs, value_regno);
                                 }
                         } else {
                                 mark_reg_known_zero(env, regs,
                                                     value_regno);
                                 if (type_may_be_null(reg_type))
                                         regs[value_regno].id = ++env->id_gen;
                                 /* A load of ctx field could have different
                                  * actual load size with the one encoded in the
                                  * insn. When the dst is PTR, it is for sure not
                                  * a sub-register.
                                  */
                                 regs[value_regno].subreg_def = DEF_NOT_SUBREG;
                                 if (base_type(reg_type) == PTR_TO_BTF_ID) {
                                         regs[value_regno].btf = btf;
                                         regs[value_regno].btf_id = btf_id;
                                 }
                         }
                         regs[value_regno].type = reg_type;
                 }
 
         } else if (reg->type == PTR_TO_STACK) {
                 /* Basic bounds checks. */
                 err = check_stack_access_within_bounds(env, regno, off, size, ACCESS_DIRECT, t);
                 if (err)
                         return err;
 
                 if (t == BPF_READ)
                         err = check_stack_read(env, regno, off, size,
                                                value_regno);
                 else
                         err = check_stack_write(env, regno, off, size,
                                                 value_regno, insn_idx);
         } else if (reg_is_pkt_pointer(reg)) {
                 if (t == BPF_WRITE && !may_access_direct_pkt_data(env, NULL, t)) {
                         verbose(env, "cannot write into packet\n");
                         return -EACCES;
                 }
                 if (t == BPF_WRITE && value_regno >= 0 &&
                     is_pointer_value(env, value_regno)) {
                         verbose(env, "R%d leaks addr into packet\n",
                                 value_regno);
                         return -EACCES;
                 }
                 err = check_packet_access(env, regno, off, size, false);
                 if (!err && t == BPF_READ && value_regno >= 0)
                         mark_reg_unknown(env, regs, value_regno);
         } else if (reg->type == PTR_TO_FLOW_KEYS) {
                 if (t == BPF_WRITE && value_regno >= 0 &&
                     is_pointer_value(env, value_regno)) {
                         verbose(env, "R%d leaks addr into flow keys\n",
                                 value_regno);
                         return -EACCES;
                 }
 
                 err = check_flow_keys_access(env, off, size);
                 if (!err && t == BPF_READ && value_regno >= 0)
                         mark_reg_unknown(env, regs, value_regno);
         } else if (type_is_sk_pointer(reg->type)) {
                 if (t == BPF_WRITE) {
                         verbose(env, "R%d cannot write into %s\n",
                                 regno, reg_type_str(env, reg->type));
                         return -EACCES;
                 }
                 err = check_sock_access(env, insn_idx, regno, off, size, t);
                 if (!err && value_regno >= 0)
                         mark_reg_unknown(env, regs, value_regno);
         } else if (reg->type == PTR_TO_TP_BUFFER) {
                 err = check_tp_buffer_access(env, reg, regno, off, size);
                 if (!err && t == BPF_READ && value_regno >= 0)
                         mark_reg_unknown(env, regs, value_regno);
         } else if (base_type(reg->type) == PTR_TO_BTF_ID &&
                    !type_may_be_null(reg->type)) {
                 err = check_ptr_to_btf_access(env, regs, regno, off, size, t,
                                               value_regno);
         } else if (reg->type == CONST_PTR_TO_MAP) {
                 err = check_ptr_to_map_access(env, regs, regno, off, size, t,
                                               value_regno);
         } else if (base_type(reg->type) == PTR_TO_BUF) {
                 bool rdonly_mem = type_is_rdonly_mem(reg->type);
                 u32 *max_access;
 
                 if (rdonly_mem) {
                         if (t == BPF_WRITE) {
                                 verbose(env, "R%d cannot write into %s\n",
                                         regno, reg_type_str(env, reg->type));
                                 return -EACCES;
                         }
                         max_access = &env->prog->aux->max_rdonly_access;
                 } else {
                         max_access = &env->prog->aux->max_rdwr_access;
                 }
 
                 err = check_buffer_access(env, reg, regno, off, size, false,
                                           max_access);
 
                 if (!err && value_regno >= 0 && (rdonly_mem || t == BPF_READ))
                         mark_reg_unknown(env, regs, value_regno);
         } else if (reg->type == PTR_TO_ARENA) {
                 if (t == BPF_READ && value_regno >= 0)
                         mark_reg_unknown(env, regs, value_regno);
         } else {
                 verbose(env, "R%d invalid mem access '%s'\n", regno,
                         reg_type_str(env, reg->type));
                 return -EACCES;
         }
 
         if (!err && size < BPF_REG_SIZE && value_regno >= 0 && t == BPF_READ &&
             regs[value_regno].type == SCALAR_VALUE) {
                 if (!is_ldsx)
                         /* b/h/w load zero-extends, mark upper bits as known 0 */
                         coerce_reg_to_size(&regs[value_regno], size);
                 else
                         coerce_reg_to_size_sx(&regs[value_regno], size);
         }
         return err;
 }
 
 static int save_aux_ptr_type(struct bpf_verifier_env *env, enum bpf_reg_type type,
                              bool allow_trust_mismatch);
 
 static int check_atomic(struct bpf_verifier_env *env, int insn_idx, struct bpf_insn *insn)
 {
         int load_reg;
         int err;
 
         switch (insn->imm) {
         case BPF_ADD:
         case BPF_ADD | BPF_FETCH:
         case BPF_AND:
         case BPF_AND | BPF_FETCH:
         case BPF_OR:
         case BPF_OR | BPF_FETCH:
         case BPF_XOR:
         case BPF_XOR | BPF_FETCH:
         case BPF_XCHG:
         case BPF_CMPXCHG:
                 break;
         default:
                 verbose(env, "BPF_ATOMIC uses invalid atomic opcode %02x\n", insn->imm);
                 return -EINVAL;
         }
 
         if (BPF_SIZE(insn->code) != BPF_W && BPF_SIZE(insn->code) != BPF_DW) {
                 verbose(env, "invalid atomic operand size\n");
                 return -EINVAL;
         }
 
         /* check src1 operand */
         err = check_reg_arg(env, insn->src_reg, SRC_OP);
         if (err)
                 return err;
 
         /* check src2 operand */
         err = check_reg_arg(env, insn->dst_reg, SRC_OP);
         if (err)
                 return err;
 
         if (insn->imm == BPF_CMPXCHG) {
                 /* Check comparison of R0 with memory location */
                 const u32 aux_reg = BPF_REG_0;
 
                 err = check_reg_arg(env, aux_reg, SRC_OP);
                 if (err)
                         return err;
 
                 if (is_pointer_value(env, aux_reg)) {
                         verbose(env, "R%d leaks addr into mem\n", aux_reg);
                         return -EACCES;
                 }
         }
 
         if (is_pointer_value(env, insn->src_reg)) {
                 verbose(env, "R%d leaks addr into mem\n", insn->src_reg);
                 return -EACCES;
         }
 
         if (is_ctx_reg(env, insn->dst_reg) ||
             is_pkt_reg(env, insn->dst_reg) ||
             is_flow_key_reg(env, insn->dst_reg) ||
             is_sk_reg(env, insn->dst_reg) ||
             (is_arena_reg(env, insn->dst_reg) && !bpf_jit_supports_insn(insn, true))) {
                 verbose(env, "BPF_ATOMIC stores into R%d %s is not allowed\n",
                         insn->dst_reg,
                         reg_type_str(env, reg_state(env, insn->dst_reg)->type));
                 return -EACCES;
         }
 
         if (insn->imm & BPF_FETCH) {
                 if (insn->imm == BPF_CMPXCHG)
                         load_reg = BPF_REG_0;
                 else
                         load_reg = insn->src_reg;
 
                 /* check and record load of old value */
                 err = check_reg_arg(env, load_reg, DST_OP);
                 if (err)
                         return err;
         } else {
                 /* This instruction accesses a memory location but doesn't
                  * actually load it into a register.
                  */
                 load_reg = -1;
         }
 
         /* Check whether we can read the memory, with second call for fetch
          * case to simulate the register fill.
          */
         err = check_mem_access(env, insn_idx, insn->dst_reg, insn->off,
                                BPF_SIZE(insn->code), BPF_READ, -1, true, false);
         if (!err && load_reg >= 0)
                 err = check_mem_access(env, insn_idx, insn->dst_reg, insn->off,
                                        BPF_SIZE(insn->code), BPF_READ, load_reg,
                                        true, false);
         if (err)
                 return err;
 
         if (is_arena_reg(env, insn->dst_reg)) {
                 err = save_aux_ptr_type(env, PTR_TO_ARENA, false);
                 if (err)
                         return err;
         }
         /* Check whether we can write into the same memory. */
         err = check_mem_access(env, insn_idx, insn->dst_reg, insn->off,
                                BPF_SIZE(insn->code), BPF_WRITE, -1, true, false);
         if (err)
                 return err;
         return 0;
 }
 
 /* When register 'regno' is used to read the stack (either directly or through
  * a helper function) make sure that it's within stack boundary and, depending
  * on the access type and privileges, that all elements of the stack are
  * initialized.
  *
  * 'off' includes 'regno->off', but not its dynamic part (if any).
  *
  * All registers that have been spilled on the stack in the slots within the
  * read offsets are marked as read.
  */
 static int check_stack_range_initialized(
                 struct bpf_verifier_env *env, int regno, int off,
                 int access_size, bool zero_size_allowed,
                 enum bpf_access_src type, struct bpf_call_arg_meta *meta)
 {
         struct bpf_reg_state *reg = reg_state(env, regno);
         struct bpf_func_state *state = func(env, reg);
         int err, min_off, max_off, i, j, slot, spi;
         char *err_extra = type == ACCESS_HELPER ? " indirect" : "";
         enum bpf_access_type bounds_check_type;
         /* Some accesses can write anything into the stack, others are
          * read-only.
          */
         bool clobber = false;
 
         if (access_size == 0 && !zero_size_allowed) {
                 verbose(env, "invalid zero-sized read\n");
                 return -EACCES;
         }
 
         if (type == ACCESS_HELPER) {
                 /* The bounds checks for writes are more permissive than for
                  * reads. However, if raw_mode is not set, we'll do extra
                  * checks below.
                  */
                 bounds_check_type = BPF_WRITE;
                 clobber = true;
         } else {
                 bounds_check_type = BPF_READ;
         }
         err = check_stack_access_within_bounds(env, regno, off, access_size,
                                                type, bounds_check_type);
         if (err)
                 return err;
 
 
         if (tnum_is_const(reg->var_off)) {
                 min_off = max_off = reg->var_off.value + off;
         } else {
                 /* Variable offset is prohibited for unprivileged mode for
                  * simplicity since it requires corresponding support in
                  * Spectre masking for stack ALU.
                  * See also retrieve_ptr_limit().
                  */
                 if (!env->bypass_spec_v1) {
                         char tn_buf[48];
 
                         tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
                         verbose(env, "R%d%s variable offset stack access prohibited for !root, var_off=%s\n",
                                 regno, err_extra, tn_buf);
                         return -EACCES;
                 }
                 /* Only initialized buffer on stack is allowed to be accessed
                  * with variable offset. With uninitialized buffer it's hard to
                  * guarantee that whole memory is marked as initialized on
                  * helper return since specific bounds are unknown what may
                  * cause uninitialized stack leaking.
                  */
                 if (meta && meta->raw_mode)
                         meta = NULL;
 
                 min_off = reg->smin_value + off;
                 max_off = reg->smax_value + off;
         }
 
         if (meta && meta->raw_mode) {
                 /* Ensure we won't be overwriting dynptrs when simulating byte
                  * by byte access in check_helper_call using meta.access_size.
                  * This would be a problem if we have a helper in the future
                  * which takes:
                  *
                  *      helper(uninit_mem, len, dynptr)
                  *
                  * Now, uninint_mem may overlap with dynptr pointer. Hence, it
                  * may end up writing to dynptr itself when touching memory from
                  * arg 1. This can be relaxed on a case by case basis for known
                  * safe cases, but reject due to the possibilitiy of aliasing by
                  * default.
                  */
                 for (i = min_off; i < max_off + access_size; i++) {
                         int stack_off = -i - 1;
 
                         spi = __get_spi(i);
                         /* raw_mode may write past allocated_stack */
                         if (state->allocated_stack <= stack_off)
                                 continue;
                         if (state->stack[spi].slot_type[stack_off % BPF_REG_SIZE] == STACK_DYNPTR) {
                                 verbose(env, "potential write to dynptr at off=%d disallowed\n", i);
                                 return -EACCES;
                         }
                 }
                 meta->access_size = access_size;
                 meta->regno = regno;
                 return 0;
         }
 
         for (i = min_off; i < max_off + access_size; i++) {
                 u8 *stype;
 
                 slot = -i - 1;
                 spi = slot / BPF_REG_SIZE;
                 if (state->allocated_stack <= slot) {
                         verbose(env, "verifier bug: allocated_stack too small");
                         return -EFAULT;
                 }
 
                 stype = &state->stack[spi].slot_type[slot % BPF_REG_SIZE];
                 if (*stype == STACK_MISC)
                         goto mark;
                 if ((*stype == STACK_ZERO) ||
                     (*stype == STACK_INVALID && env->allow_uninit_stack)) {
                         if (clobber) {
                                 /* helper can write anything into the stack */
                                 *stype = STACK_MISC;
                         }
                         goto mark;
                 }
 
                 if (is_spilled_reg(&state->stack[spi]) &&
                     (state->stack[spi].spilled_ptr.type == SCALAR_VALUE ||
                      env->allow_ptr_leaks)) {
                         if (clobber) {
                                 __mark_reg_unknown(env, &state->stack[spi].spilled_ptr);
                                 for (j = 0; j < BPF_REG_SIZE; j++)
                                         scrub_spilled_slot(&state->stack[spi].slot_type[j]);
                         }
                         goto mark;
                 }
 
                 if (tnum_is_const(reg->var_off)) {
                         verbose(env, "invalid%s read from stack R%d off %d+%d size %d\n",
                                 err_extra, regno, min_off, i - min_off, access_size);
                 } else {
                         char tn_buf[48];
 
                         tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
                         verbose(env, "invalid%s read from stack R%d var_off %s+%d size %d\n",
                                 err_extra, regno, tn_buf, i - min_off, access_size);
                 }
                 return -EACCES;
 mark:
                 /* reading any byte out of 8-byte 'spill_slot' will cause
                  * the whole slot to be marked as 'read'
                  */
                 mark_reg_read(env, &state->stack[spi].spilled_ptr,
                               state->stack[spi].spilled_ptr.parent,
                               REG_LIVE_READ64);
                 /* We do not set REG_LIVE_WRITTEN for stack slot, as we can not
                  * be sure that whether stack slot is written to or not. Hence,
                  * we must still conservatively propagate reads upwards even if
                  * helper may write to the entire memory range.
                  */
         }
         return 0;
 }
 
 static int check_helper_mem_access(struct bpf_verifier_env *env, int regno,
                                    int access_size, bool zero_size_allowed,
                                    struct bpf_call_arg_meta *meta)
 {
         struct bpf_reg_state *regs = cur_regs(env), *reg = &regs[regno];
         u32 *max_access;
 
         switch (base_type(reg->type)) {
         case PTR_TO_PACKET:
         case PTR_TO_PACKET_META:
                 return check_packet_access(env, regno, reg->off, access_size,
                                            zero_size_allowed);
         case PTR_TO_MAP_KEY:
                 if (meta && meta->raw_mode) {
                         verbose(env, "R%d cannot write into %s\n", regno,
                                 reg_type_str(env, reg->type));
                         return -EACCES;
                 }
                 return check_mem_region_access(env, regno, reg->off, access_size,
                                                reg->map_ptr->key_size, false);
         case PTR_TO_MAP_VALUE:
                 if (check_map_access_type(env, regno, reg->off, access_size,
                                           meta && meta->raw_mode ? BPF_WRITE :
                                           BPF_READ))
                         return -EACCES;
                 return check_map_access(env, regno, reg->off, access_size,
                                         zero_size_allowed, ACCESS_HELPER);
         case PTR_TO_MEM:
                 if (type_is_rdonly_mem(reg->type)) {
                         if (meta && meta->raw_mode) {
                                 verbose(env, "R%d cannot write into %s\n", regno,
                                         reg_type_str(env, reg->type));
                                 return -EACCES;
                         }
                 }
                 return check_mem_region_access(env, regno, reg->off,
                                                access_size, reg->mem_size,
                                                zero_size_allowed);
         case PTR_TO_BUF:
                 if (type_is_rdonly_mem(reg->type)) {
                         if (meta && meta->raw_mode) {
                                 verbose(env, "R%d cannot write into %s\n", regno,
                                         reg_type_str(env, reg->type));
                                 return -EACCES;
                         }
 
                         max_access = &env->prog->aux->max_rdonly_access;
                 } else {
                         max_access = &env->prog->aux->max_rdwr_access;
                 }
                 return check_buffer_access(env, reg, regno, reg->off,
                                            access_size, zero_size_allowed,
                                            max_access);
         case PTR_TO_STACK:
                 return check_stack_range_initialized(
                                 env,
                                 regno, reg->off, access_size,
                                 zero_size_allowed, ACCESS_HELPER, meta);
         case PTR_TO_BTF_ID:
                 return check_ptr_to_btf_access(env, regs, regno, reg->off,
                                                access_size, BPF_READ, -1);
         case PTR_TO_CTX:
                 /* in case the function doesn't know how to access the context,
                  * (because we are in a program of type SYSCALL for example), we
                  * can not statically check its size.
                  * Dynamically check it now.
                  */
                 if (!env->ops->convert_ctx_access) {
                         enum bpf_access_type atype = meta && meta->raw_mode ? BPF_WRITE : BPF_READ;
                         int offset = access_size - 1;
 
                         /* Allow zero-byte read from PTR_TO_CTX */
                         if (access_size == 0)
                                 return zero_size_allowed ? 0 : -EACCES;
 
                         return check_mem_access(env, env->insn_idx, regno, offset, BPF_B,
                                                 atype, -1, false, false);
                 }
 
                 fallthrough;
         default: /* scalar_value or invalid ptr */
                 /* Allow zero-byte read from NULL, regardless of pointer type */
                 if (zero_size_allowed && access_size == 0 &&
                     register_is_null(reg))
                         return 0;
 
                 verbose(env, "R%d type=%s ", regno,
                         reg_type_str(env, reg->type));
                 verbose(env, "expected=%s\n", reg_type_str(env, PTR_TO_STACK));
                 return -EACCES;
         }
 }
 
 /* verify arguments to helpers or kfuncs consisting of a pointer and an access
  * size.
  *
  * @regno is the register containing the access size. regno-1 is the register
  * containing the pointer.
  */
 static int check_mem_size_reg(struct bpf_verifier_env *env,
                               struct bpf_reg_state *reg, u32 regno,
                               bool zero_size_allowed,
                               struct bpf_call_arg_meta *meta)
 {
         int err;
 
         /* This is used to refine r0 return value bounds for helpers
          * that enforce this value as an upper bound on return values.
          * See do_refine_retval_range() for helpers that can refine
          * the return value. C type of helper is u32 so we pull register
          * bound from umax_value however, if negative verifier errors
          * out. Only upper bounds can be learned because retval is an
          * int type and negative retvals are allowed.
          */
         meta->msize_max_value = reg->umax_value;
 
         /* The register is SCALAR_VALUE; the access check
          * happens using its boundaries.
          */
         if (!tnum_is_const(reg->var_off))
                 /* For unprivileged variable accesses, disable raw
                  * mode so that the program is required to
                  * initialize all the memory that the helper could
                  * just partially fill up.
                  */
                 meta = NULL;
 
         if (reg->smin_value < 0) {
                 verbose(env, "R%d min value is negative, either use unsigned or 'var &= const'\n",
                         regno);
                 return -EACCES;
         }
 
         if (reg->umin_value == 0 && !zero_size_allowed) {
                 verbose(env, "R%d invalid zero-sized read: u64=[%lld,%lld]\n",
                         regno, reg->umin_value, reg->umax_value);
                 return -EACCES;
         }
 
         if (reg->umax_value >= BPF_MAX_VAR_SIZ) {
                 verbose(env, "R%d unbounded memory access, use 'var &= const' or 'if (var < const)'\n",
                         regno);
                 return -EACCES;
         }
         err = check_helper_mem_access(env, regno - 1,
                                       reg->umax_value,
                                       zero_size_allowed, meta);
         if (!err)
                 err = mark_chain_precision(env, regno);
         return err;
 }
 
 static int check_mem_reg(struct bpf_verifier_env *env, struct bpf_reg_state *reg,
                          u32 regno, u32 mem_size)
 {
         bool may_be_null = type_may_be_null(reg->type);
         struct bpf_reg_state saved_reg;
         struct bpf_call_arg_meta meta;
         int err;
 
         if (register_is_null(reg))
                 return 0;
 
         memset(&meta, 0, sizeof(meta));
         /* Assuming that the register contains a value check if the memory
          * access is safe. Temporarily save and restore the register's state as
          * the conversion shouldn't be visible to a caller.
          */
         if (may_be_null) {
                 saved_reg = *reg;
                 mark_ptr_not_null_reg(reg);
         }
 
         err = check_helper_mem_access(env, regno, mem_size, true, &meta);
         /* Check access for BPF_WRITE */
         meta.raw_mode = true;
         err = err ?: check_helper_mem_access(env, regno, mem_size, true, &meta);
 
         if (may_be_null)
                 *reg = saved_reg;
 
         return err;
 }
 
 static int check_kfunc_mem_size_reg(struct bpf_verifier_env *env, struct bpf_reg_state *reg,
                                     u32 regno)
 {
         struct bpf_reg_state *mem_reg = &cur_regs(env)[regno - 1];
         bool may_be_null = type_may_be_null(mem_reg->type);
         struct bpf_reg_state saved_reg;
         struct bpf_call_arg_meta meta;
         int err;
 
         WARN_ON_ONCE(regno < BPF_REG_2 || regno > BPF_REG_5);
 
         memset(&meta, 0, sizeof(meta));
 
         if (may_be_null) {
                 saved_reg = *mem_reg;
                 mark_ptr_not_null_reg(mem_reg);
         }
 
         err = check_mem_size_reg(env, reg, regno, true, &meta);
         /* Check access for BPF_WRITE */
         meta.raw_mode = true;
         err = err ?: check_mem_size_reg(env, reg, regno, true, &meta);
 
         if (may_be_null)
                 *mem_reg = saved_reg;
         return err;
 }
 
 /* Implementation details:
  * bpf_map_lookup returns PTR_TO_MAP_VALUE_OR_NULL.
  * bpf_obj_new returns PTR_TO_BTF_ID | MEM_ALLOC | PTR_MAYBE_NULL.
  * Two bpf_map_lookups (even with the same key) will have different reg->id.
  * Two separate bpf_obj_new will also have different reg->id.
  * For traditional PTR_TO_MAP_VALUE or PTR_TO_BTF_ID | MEM_ALLOC, the verifier
  * clears reg->id after value_or_null->value transition, since the verifier only
  * cares about the range of access to valid map value pointer and doesn't care
  * about actual address of the map element.
  * For maps with 'struct bpf_spin_lock' inside map value the verifier keeps
  * reg->id > 0 after value_or_null->value transition. By doing so
  * two bpf_map_lookups will be considered two different pointers that
  * point to different bpf_spin_locks. Likewise for pointers to allocated objects
  * returned from bpf_obj_new.
  * The verifier allows taking only one bpf_spin_lock at a time to avoid
  * dead-locks.
  * Since only one bpf_spin_lock is allowed the checks are simpler than
  * reg_is_refcounted() logic. The verifier needs to remember only
  * one spin_lock instead of array of acquired_refs.
  * cur_state->active_lock remembers which map value element or allocated
  * object got locked and clears it after bpf_spin_unlock.
  */
 static int process_spin_lock(struct bpf_verifier_env *env, int regno,
                              bool is_lock)
 {
         struct bpf_reg_state *regs = cur_regs(env), *reg = &regs[regno];
         struct bpf_verifier_state *cur = env->cur_state;
         bool is_const = tnum_is_const(reg->var_off);
         u64 val = reg->var_off.value;
         struct bpf_map *map = NULL;
         struct btf *btf = NULL;
         struct btf_record *rec;
 
         if (!is_const) {
                 verbose(env,
                         "R%d doesn't have constant offset. bpf_spin_lock has to be at the constant offset\n",
                         regno);
                 return -EINVAL;
         }
         if (reg->type == PTR_TO_MAP_VALUE) {
                 map = reg->map_ptr;
                 if (!map->btf) {
                         verbose(env,
                                 "map '%s' has to have BTF in order to use bpf_spin_lock\n",
                                 map->name);
                         return -EINVAL;
                 }
         } else {
                 btf = reg->btf;
         }
 
         rec = reg_btf_record(reg);
         if (!btf_record_has_field(rec, BPF_SPIN_LOCK)) {
                 verbose(env, "%s '%s' has no valid bpf_spin_lock\n", map ? "map" : "local",
                         map ? map->name : "kptr");
                 return -EINVAL;
         }
         if (rec->spin_lock_off != val + reg->off) {
                 verbose(env, "off %lld doesn't point to 'struct bpf_spin_lock' that is at %d\n",
                         val + reg->off, rec->spin_lock_off);
                 return -EINVAL;
         }
         if (is_lock) {
                 if (cur->active_lock.ptr) {
                         verbose(env,
                                 "Locking two bpf_spin_locks are not allowed\n");
                         return -EINVAL;
                 }
                 if (map)
                         cur->active_lock.ptr = map;
                 else
                         cur->active_lock.ptr = btf;
                 cur->active_lock.id = reg->id;
         } else {
                 void *ptr;
 
                 if (map)
                         ptr = map;
                 else
                         ptr = btf;
 
                 if (!cur->active_lock.ptr) {
                         verbose(env, "bpf_spin_unlock without taking a lock\n");
                         return -EINVAL;
                 }
                 if (cur->active_lock.ptr != ptr ||
                     cur->active_lock.id != reg->id) {
                         verbose(env, "bpf_spin_unlock of different lock\n");
                         return -EINVAL;
                 }
 
                 invalidate_non_owning_refs(env);
 
                 cur->active_lock.ptr = NULL;
                 cur->active_lock.id = 0;
         }
         return 0;
 }
 
 static int process_timer_func(struct bpf_verifier_env *env, int regno,
                               struct bpf_call_arg_meta *meta)
 {
         struct bpf_reg_state *regs = cur_regs(env), *reg = &regs[regno];
         bool is_const = tnum_is_const(reg->var_off);
         struct bpf_map *map = reg->map_ptr;
         u64 val = reg->var_off.value;
 
         if (!is_const) {
                 verbose(env,
                         "R%d doesn't have constant offset. bpf_timer has to be at the constant offset\n",
                         regno);
                 return -EINVAL;
         }
         if (!map->btf) {
                 verbose(env, "map '%s' has to have BTF in order to use bpf_timer\n",
                         map->name);
                 return -EINVAL;
         }
         if (!btf_record_has_field(map->record, BPF_TIMER)) {
                 verbose(env, "map '%s' has no valid bpf_timer\n", map->name);
                 return -EINVAL;
         }
         if (map->record->timer_off != val + reg->off) {
                 verbose(env, "off %lld doesn't point to 'struct bpf_timer' that is at %d\n",
                         val + reg->off, map->record->timer_off);
                 return -EINVAL;
         }
         if (meta->map_ptr) {
                 verbose(env, "verifier bug. Two map pointers in a timer helper\n");
                 return -EFAULT;
         }
         meta->map_uid = reg->map_uid;
         meta->map_ptr = map;
         return 0;
 }
 
 static int process_wq_func(struct bpf_verifier_env *env, int regno,
                            struct bpf_kfunc_call_arg_meta *meta)
 {
         struct bpf_reg_state *regs = cur_regs(env), *reg = &regs[regno];
         struct bpf_map *map = reg->map_ptr;
         u64 val = reg->var_off.value;
 
         if (map->record->wq_off != val + reg->off) {
                 verbose(env, "off %lld doesn't point to 'struct bpf_wq' that is at %d\n",
                         val + reg->off, map->record->wq_off);
                 return -EINVAL;
         }
         meta->map.uid = reg->map_uid;
         meta->map.ptr = map;
         return 0;
 }
 
 static int process_kptr_func(struct bpf_verifier_env *env, int regno,
                              struct bpf_call_arg_meta *meta)
 {
         struct bpf_reg_state *regs = cur_regs(env), *reg = &regs[regno];
         struct bpf_map *map_ptr = reg->map_ptr;
         struct btf_field *kptr_field;
         u32 kptr_off;
 
         if (!tnum_is_const(reg->var_off)) {
                 verbose(env,
                         "R%d doesn't have constant offset. kptr has to be at the constant offset\n",
                         regno);
                 return -EINVAL;
         }
         if (!map_ptr->btf) {
                 verbose(env, "map '%s' has to have BTF in order to use bpf_kptr_xchg\n",
                         map_ptr->name);
                 return -EINVAL;
         }
         if (!btf_record_has_field(map_ptr->record, BPF_KPTR)) {
                 verbose(env, "map '%s' has no valid kptr\n", map_ptr->name);
                 return -EINVAL;
         }
 
         meta->map_ptr = map_ptr;
         kptr_off = reg->off + reg->var_off.value;
         kptr_field = btf_record_find(map_ptr->record, kptr_off, BPF_KPTR);
         if (!kptr_field) {
                 verbose(env, "off=%d doesn't point to kptr\n", kptr_off);
                 return -EACCES;
         }
         if (kptr_field->type != BPF_KPTR_REF && kptr_field->type != BPF_KPTR_PERCPU) {
                 verbose(env, "off=%d kptr isn't referenced kptr\n", kptr_off);
                 return -EACCES;
         }
         meta->kptr_field = kptr_field;
         return 0;
 }
 
 /* There are two register types representing a bpf_dynptr, one is PTR_TO_STACK
  * which points to a stack slot, and the other is CONST_PTR_TO_DYNPTR.
  *
  * In both cases we deal with the first 8 bytes, but need to mark the next 8
  * bytes as STACK_DYNPTR in case of PTR_TO_STACK. In case of
  * CONST_PTR_TO_DYNPTR, we are guaranteed to get the beginning of the object.
  *
  * Mutability of bpf_dynptr is at two levels, one is at the level of struct
  * bpf_dynptr itself, i.e. whether the helper is receiving a pointer to struct
  * bpf_dynptr or pointer to const struct bpf_dynptr. In the former case, it can
  * mutate the view of the dynptr and also possibly destroy it. In the latter
  * case, it cannot mutate the bpf_dynptr itself but it can still mutate the
  * memory that dynptr points to.
  *
  * The verifier will keep track both levels of mutation (bpf_dynptr's in
  * reg->type and the memory's in reg->dynptr.type), but there is no support for
  * readonly dynptr view yet, hence only the first case is tracked and checked.
  *
  * This is consistent with how C applies the const modifier to a struct object,
  * where the pointer itself inside bpf_dynptr becomes const but not what it
  * points to.
  *
  * Helpers which do not mutate the bpf_dynptr set MEM_RDONLY in their argument
  * type, and declare it as 'const struct bpf_dynptr *' in their prototype.
  */
 static int process_dynptr_func(struct bpf_verifier_env *env, int regno, int insn_idx,
                                enum bpf_arg_type arg_type, int clone_ref_obj_id)
 {
         struct bpf_reg_state *regs = cur_regs(env), *reg = &regs[regno];
         int err;
 
         if (reg->type != PTR_TO_STACK && reg->type != CONST_PTR_TO_DYNPTR) {
                 verbose(env,
                         "arg#%d expected pointer to stack or const struct bpf_dynptr\n",
                         regno);
                 return -EINVAL;
         }
 
         /* MEM_UNINIT and MEM_RDONLY are exclusive, when applied to an
          * ARG_PTR_TO_DYNPTR (or ARG_PTR_TO_DYNPTR | DYNPTR_TYPE_*):
          */
         if ((arg_type & (MEM_UNINIT | MEM_RDONLY)) == (MEM_UNINIT | MEM_RDONLY)) {
                 verbose(env, "verifier internal error: misconfigured dynptr helper type flags\n");
                 return -EFAULT;
         }
 
         /*  MEM_UNINIT - Points to memory that is an appropriate candidate for
          *               constructing a mutable bpf_dynptr object.
          *
          *               Currently, this is only possible with PTR_TO_STACK
          *               pointing to a region of at least 16 bytes which doesn't
          *               contain an existing bpf_dynptr.
          *
          *  MEM_RDONLY - Points to a initialized bpf_dynptr that will not be
          *               mutated or destroyed. However, the memory it points to
          *               may be mutated.
          *
          *  None       - Points to a initialized dynptr that can be mutated and
          *               destroyed, including mutation of the memory it points
          *               to.
          */
         if (arg_type & MEM_UNINIT) {
                 int i;
 
                 if (!is_dynptr_reg_valid_uninit(env, reg)) {
                         verbose(env, "Dynptr has to be an uninitialized dynptr\n");
                         return -EINVAL;
                 }
 
                 /* we write BPF_DW bits (8 bytes) at a time */
                 for (i = 0; i < BPF_DYNPTR_SIZE; i += 8) {
                         err = check_mem_access(env, insn_idx, regno,
                                                i, BPF_DW, BPF_WRITE, -1, false, false);
                         if (err)
                                 return err;
                 }
 
                 err = mark_stack_slots_dynptr(env, reg, arg_type, insn_idx, clone_ref_obj_id);
         } else /* MEM_RDONLY and None case from above */ {
                 /* For the reg->type == PTR_TO_STACK case, bpf_dynptr is never const */
                 if (reg->type == CONST_PTR_TO_DYNPTR && !(arg_type & MEM_RDONLY)) {
                         verbose(env, "cannot pass pointer to const bpf_dynptr, the helper mutates it\n");
                         return -EINVAL;
                 }
 
                 if (!is_dynptr_reg_valid_init(env, reg)) {
                         verbose(env,
                                 "Expected an initialized dynptr as arg #%d\n",
                                 regno);
                         return -EINVAL;
                 }
 
                 /* Fold modifiers (in this case, MEM_RDONLY) when checking expected type */
                 if (!is_dynptr_type_expected(env, reg, arg_type & ~MEM_RDONLY)) {
                         verbose(env,
                                 "Expected a dynptr of type %s as arg #%d\n",
                                 dynptr_type_str(arg_to_dynptr_type(arg_type)), regno);
                         return -EINVAL;
                 }
 
                 err = mark_dynptr_read(env, reg);
         }
         return err;
 }
 
 static u32 iter_ref_obj_id(struct bpf_verifier_env *env, struct bpf_reg_state *reg, int spi)
 {
         struct bpf_func_state *state = func(env, reg);
 
         return state->stack[spi].spilled_ptr.ref_obj_id;
 }
 
 static bool is_iter_kfunc(struct bpf_kfunc_call_arg_meta *meta)
 {
         return meta->kfunc_flags & (KF_ITER_NEW | KF_ITER_NEXT | KF_ITER_DESTROY);
 }
 
 static bool is_iter_new_kfunc(struct bpf_kfunc_call_arg_meta *meta)
 {
         return meta->kfunc_flags & KF_ITER_NEW;
 }
 
 static bool is_iter_next_kfunc(struct bpf_kfunc_call_arg_meta *meta)
 {
         return meta->kfunc_flags & KF_ITER_NEXT;
 }
 
 static bool is_iter_destroy_kfunc(struct bpf_kfunc_call_arg_meta *meta)
 {
         return meta->kfunc_flags & KF_ITER_DESTROY;
 }
 
 static bool is_kfunc_arg_iter(struct bpf_kfunc_call_arg_meta *meta, int arg)
 {
         /* btf_check_iter_kfuncs() guarantees that first argument of any iter
          * kfunc is iter state pointer
          */
         return arg == 0 && is_iter_kfunc(meta);
 }
 
 static int process_iter_arg(struct bpf_verifier_env *env, int regno, int insn_idx,
                             struct bpf_kfunc_call_arg_meta *meta)
 {
         struct bpf_reg_state *regs = cur_regs(env), *reg = &regs[regno];
         const struct btf_type *t;
         const struct btf_param *arg;
         int spi, err, i, nr_slots;
         u32 btf_id;
 
         /* btf_check_iter_kfuncs() ensures we don't need to validate anything here */
         arg = &btf_params(meta->func_proto)[0];
         t = btf_type_skip_modifiers(meta->btf, arg->type, NULL);        /* PTR */
         t = btf_type_skip_modifiers(meta->btf, t->type, &btf_id);       /* STRUCT */
         nr_slots = t->size / BPF_REG_SIZE;
 
         if (is_iter_new_kfunc(meta)) {
                 /* bpf_iter_<type>_new() expects pointer to uninit iter state */
                 if (!is_iter_reg_valid_uninit(env, reg, nr_slots)) {
                         verbose(env, "expected uninitialized iter_%s as arg #%d\n",
                                 iter_type_str(meta->btf, btf_id), regno);
                         return -EINVAL;
                 }
 
                 for (i = 0; i < nr_slots * 8; i += BPF_REG_SIZE) {
                         err = check_mem_access(env, insn_idx, regno,
                                                i, BPF_DW, BPF_WRITE, -1, false, false);
                         if (err)
                                 return err;
                 }
 
                 err = mark_stack_slots_iter(env, meta, reg, insn_idx, meta->btf, btf_id, nr_slots);
                 if (err)
                         return err;
         } else {
                 /* iter_next() or iter_destroy() expect initialized iter state*/
                 err = is_iter_reg_valid_init(env, reg, meta->btf, btf_id, nr_slots);
                 switch (err) {
                 case 0:
                         break;
                 case -EINVAL:
                         verbose(env, "expected an initialized iter_%s as arg #%d\n",
                                 iter_type_str(meta->btf, btf_id), regno);
                         return err;
                 case -EPROTO:
                         verbose(env, "expected an RCU CS when using %s\n", meta->func_name);
                         return err;
                 default:
                         return err;
                 }
 
                 spi = iter_get_spi(env, reg, nr_slots);
                 if (spi < 0)
                         return spi;
 
                 err = mark_iter_read(env, reg, spi, nr_slots);
                 if (err)
                         return err;
 
                 /* remember meta->iter info for process_iter_next_call() */
                 meta->iter.spi = spi;
                 meta->iter.frameno = reg->frameno;
                 meta->ref_obj_id = iter_ref_obj_id(env, reg, spi);
 
                 if (is_iter_destroy_kfunc(meta)) {
                         err = unmark_stack_slots_iter(env, reg, nr_slots);
                         if (err)
                                 return err;
                 }
         }
 
         return 0;
 }
 
 /* Look for a previous loop entry at insn_idx: nearest parent state
  * stopped at insn_idx with callsites matching those in cur->frame.
  */
 static struct bpf_verifier_state *find_prev_entry(struct bpf_verifier_env *env,
                                                   struct bpf_verifier_state *cur,
                                                   int insn_idx)
 {
         struct bpf_verifier_state_list *sl;
         struct bpf_verifier_state *st;
 
         /* Explored states are pushed in stack order, most recent states come first */
         sl = *explored_state(env, insn_idx);
         for (; sl; sl = sl->next) {
                 /* If st->branches != 0 state is a part of current DFS verification path,
                  * hence cur & st for a loop.
                  */
                 st = &sl->state;
                 if (st->insn_idx == insn_idx && st->branches && same_callsites(st, cur) &&
                     st->dfs_depth < cur->dfs_depth)
                         return st;
         }
 
         return NULL;
 }
 
 static void reset_idmap_scratch(struct bpf_verifier_env *env);
 static bool regs_exact(const struct bpf_reg_state *rold,
                        const struct bpf_reg_state *rcur,
                        struct bpf_idmap *idmap);
 
 static void maybe_widen_reg(struct bpf_verifier_env *env,
                             struct bpf_reg_state *rold, struct bpf_reg_state *rcur,
                             struct bpf_idmap *idmap)
 {
         if (rold->type != SCALAR_VALUE)
                 return;
         if (rold->type != rcur->type)
                 return;
         if (rold->precise || rcur->precise || regs_exact(rold, rcur, idmap))
                 return;
         __mark_reg_unknown(env, rcur);
 }
 
 static int widen_imprecise_scalars(struct bpf_verifier_env *env,
                                    struct bpf_verifier_state *old,
                                    struct bpf_verifier_state *cur)
 {
         struct bpf_func_state *fold, *fcur;
         int i, fr;
 
         reset_idmap_scratch(env);
         for (fr = old->curframe; fr >= 0; fr--) {
                 fold = old->frame[fr];
                 fcur = cur->frame[fr];
 
                 for (i = 0; i < MAX_BPF_REG; i++)
                         maybe_widen_reg(env,
                                         &fold->regs[i],
                                         &fcur->regs[i],
                                         &env->idmap_scratch);
 
                 for (i = 0; i < fold->allocated_stack / BPF_REG_SIZE; i++) {
                         if (!is_spilled_reg(&fold->stack[i]) ||
                             !is_spilled_reg(&fcur->stack[i]))
                                 continue;
 
                         maybe_widen_reg(env,
                                         &fold->stack[i].spilled_ptr,
                                         &fcur->stack[i].spilled_ptr,
                                         &env->idmap_scratch);
                 }
         }
         return 0;
 }
 
 static struct bpf_reg_state *get_iter_from_state(struct bpf_verifier_state *cur_st,
                                                  struct bpf_kfunc_call_arg_meta *meta)
 {
         int iter_frameno = meta->iter.frameno;
         int iter_spi = meta->iter.spi;
 
         return &cur_st->frame[iter_frameno]->stack[iter_spi].spilled_ptr;
 }
 
 /* process_iter_next_call() is called when verifier gets to iterator's next
  * "method" (e.g., bpf_iter_num_next() for numbers iterator) call. We'll refer
  * to it as just "iter_next()" in comments below.
  *
  * BPF verifier relies on a crucial contract for any iter_next()
  * implementation: it should *eventually* return NULL, and once that happens
  * it should keep returning NULL. That is, once iterator exhausts elements to
  * iterate, it should never reset or spuriously return new elements.
  *
  * With the assumption of such contract, process_iter_next_call() simulates
  * a fork in the verifier state to validate loop logic correctness and safety
  * without having to simulate infinite amount of iterations.
  *
  * In current state, we first assume that iter_next() returned NULL and
  * iterator state is set to DRAINED (BPF_ITER_STATE_DRAINED). In such
  * conditions we should not form an infinite loop and should eventually reach
  * exit.
  *
  * Besides that, we also fork current state and enqueue it for later
  * verification. In a forked state we keep iterator state as ACTIVE
  * (BPF_ITER_STATE_ACTIVE) and assume non-NULL return from iter_next(). We
  * also bump iteration depth to prevent erroneous infinite loop detection
  * later on (see iter_active_depths_differ() comment for details). In this
  * state we assume that we'll eventually loop back to another iter_next()
  * calls (it could be in exactly same location or in some other instruction,
  * it doesn't matter, we don't make any unnecessary assumptions about this,
  * everything revolves around iterator state in a stack slot, not which
  * instruction is calling iter_next()). When that happens, we either will come
  * to iter_next() with equivalent state and can conclude that next iteration
  * will proceed in exactly the same way as we just verified, so it's safe to
  * assume that loop converges. If not, we'll go on another iteration
  * simulation with a different input state, until all possible starting states
  * are validated or we reach maximum number of instructions limit.
  *
  * This way, we will either exhaustively discover all possible input states
  * that iterator loop can start with and eventually will converge, or we'll
  * effectively regress into bounded loop simulation logic and either reach
  * maximum number of instructions if loop is not provably convergent, or there
  * is some statically known limit on number of iterations (e.g., if there is
  * an explicit `if n > 100 then break;` statement somewhere in the loop).
  *
  * Iteration convergence logic in is_state_visited() relies on exact
  * states comparison, which ignores read and precision marks.
  * This is necessary because read and precision marks are not finalized
  * while in the loop. Exact comparison might preclude convergence for
  * simple programs like below:
  *
  *     i = 0;
  *     while(iter_next(&it))
  *       i++;
  *
  * At each iteration step i++ would produce a new distinct state and
  * eventually instruction processing limit would be reached.
  *
  * To avoid such behavior speculatively forget (widen) range for
  * imprecise scalar registers, if those registers were not precise at the
  * end of the previous iteration and do not match exactly.
  *
  * This is a conservative heuristic that allows to verify wide range of programs,
  * however it precludes verification of programs that conjure an
  * imprecise value on the first loop iteration and use it as precise on a second.
  * For example, the following safe program would fail to verify:
  *
  *     struct bpf_num_iter it;
  *     int arr[10];
  *     int i = 0, a = 0;
  *     bpf_iter_num_new(&it, 0, 10);
  *     while (bpf_iter_num_next(&it)) {
  *       if (a == 0) {
  *         a = 1;
  *         i = 7; // Because i changed verifier would forget
  *                // it's range on second loop entry.
  *       } else {
  *         arr[i] = 42; // This would fail to verify.
  *       }
  *     }
  *     bpf_iter_num_destroy(&it);
  */
 static int process_iter_next_call(struct bpf_verifier_env *env, int insn_idx,
                                   struct bpf_kfunc_call_arg_meta *meta)
 {
         struct bpf_verifier_state *cur_st = env->cur_state, *queued_st, *prev_st;
         struct bpf_func_state *cur_fr = cur_st->frame[cur_st->curframe], *queued_fr;
         struct bpf_reg_state *cur_iter, *queued_iter;
 
         BTF_TYPE_EMIT(struct bpf_iter);
 
         cur_iter = get_iter_from_state(cur_st, meta);
 
         if (cur_iter->iter.state != BPF_ITER_STATE_ACTIVE &&
             cur_iter->iter.state != BPF_ITER_STATE_DRAINED) {
                 verbose(env, "verifier internal error: unexpected iterator state %d (%s)\n",
                         cur_iter->iter.state, iter_state_str(cur_iter->iter.state));
                 return -EFAULT;
         }
 
         if (cur_iter->iter.state == BPF_ITER_STATE_ACTIVE) {
                 /* Because iter_next() call is a checkpoint is_state_visitied()
                  * should guarantee parent state with same call sites and insn_idx.
                  */
                 if (!cur_st->parent || cur_st->parent->insn_idx != insn_idx ||
                     !same_callsites(cur_st->parent, cur_st)) {
                         verbose(env, "bug: bad parent state for iter next call");
                         return -EFAULT;
                 }
                 /* Note cur_st->parent in the call below, it is necessary to skip
                  * checkpoint created for cur_st by is_state_visited()
                  * right at this instruction.
                  */
                 prev_st = find_prev_entry(env, cur_st->parent, insn_idx);
                 /* branch out active iter state */
                 queued_st = push_stack(env, insn_idx + 1, insn_idx, false);
                 if (!queued_st)
                         return -ENOMEM;
 
                 queued_iter = get_iter_from_state(queued_st, meta);
                 queued_iter->iter.state = BPF_ITER_STATE_ACTIVE;
                 queued_iter->iter.depth++;
                 if (prev_st)
                         widen_imprecise_scalars(env, prev_st, queued_st);
 
                 queued_fr = queued_st->frame[queued_st->curframe];
                 mark_ptr_not_null_reg(&queued_fr->regs[BPF_REG_0]);
         }
 
         /* switch to DRAINED state, but keep the depth unchanged */
         /* mark current iter state as drained and assume returned NULL */
         cur_iter->iter.state = BPF_ITER_STATE_DRAINED;
         __mark_reg_const_zero(env, &cur_fr->regs[BPF_REG_0]);
 
         return 0;
 }
 
 static bool arg_type_is_mem_size(enum bpf_arg_type type)
 {
         return type == ARG_CONST_SIZE ||
                type == ARG_CONST_SIZE_OR_ZERO;
 }
 
 static bool arg_type_is_raw_mem(enum bpf_arg_type type)
 {
         return base_type(type) == ARG_PTR_TO_MEM &&
                type & MEM_UNINIT;
 }
 
 static bool arg_type_is_release(enum bpf_arg_type type)
 {
         return type & OBJ_RELEASE;
 }
 
 static bool arg_type_is_dynptr(enum bpf_arg_type type)
 {
         return base_type(type) == ARG_PTR_TO_DYNPTR;
 }
 
 static int resolve_map_arg_type(struct bpf_verifier_env *env,
                                  const struct bpf_call_arg_meta *meta,
                                  enum bpf_arg_type *arg_type)
 {
         if (!meta->map_ptr) {
                 /* kernel subsystem misconfigured verifier */
                 verbose(env, "invalid map_ptr to access map->type\n");
                 return -EACCES;
         }
 
         switch (meta->map_ptr->map_type) {
         case BPF_MAP_TYPE_SOCKMAP:
         case BPF_MAP_TYPE_SOCKHASH:
                 if (*arg_type == ARG_PTR_TO_MAP_VALUE) {
                         *arg_type = ARG_PTR_TO_BTF_ID_SOCK_COMMON;
                 } else {
                         verbose(env, "invalid arg_type for sockmap/sockhash\n");
                         return -EINVAL;
                 }
                 break;
         case BPF_MAP_TYPE_BLOOM_FILTER:
                 if (meta->func_id == BPF_FUNC_map_peek_elem)
                         *arg_type = ARG_PTR_TO_MAP_VALUE;
                 break;
         default:
                 break;
         }
         return 0;
 }
 
 struct bpf_reg_types {
         const enum bpf_reg_type types[10];
         u32 *btf_id;
 };
 
 static const struct bpf_reg_types sock_types = {
         .types = {
                 PTR_TO_SOCK_COMMON,
                 PTR_TO_SOCKET,
                 PTR_TO_TCP_SOCK,
                 PTR_TO_XDP_SOCK,
         },
 };
 
 #ifdef CONFIG_NET
 static const struct bpf_reg_types btf_id_sock_common_types = {
         .types = {
                 PTR_TO_SOCK_COMMON,
                 PTR_TO_SOCKET,
                 PTR_TO_TCP_SOCK,
                 PTR_TO_XDP_SOCK,
                 PTR_TO_BTF_ID,
                 PTR_TO_BTF_ID | PTR_TRUSTED,
         },
         .btf_id = &btf_sock_ids[BTF_SOCK_TYPE_SOCK_COMMON],
 };
 #endif
 
 static const struct bpf_reg_types mem_types = {
         .types = {
                 PTR_TO_STACK,
                 PTR_TO_PACKET,
                 PTR_TO_PACKET_META,
                 PTR_TO_MAP_KEY,
                 PTR_TO_MAP_VALUE,
                 PTR_TO_MEM,
                 PTR_TO_MEM | MEM_RINGBUF,
                 PTR_TO_BUF,
                 PTR_TO_BTF_ID | PTR_TRUSTED,
         },
 };
 
 static const struct bpf_reg_types spin_lock_types = {
         .types = {
                 PTR_TO_MAP_VALUE,
                 PTR_TO_BTF_ID | MEM_ALLOC,
         }
 };
 
 static const struct bpf_reg_types fullsock_types = { .types = { PTR_TO_SOCKET } };
 static const struct bpf_reg_types scalar_types = { .types = { SCALAR_VALUE } };
 static const struct bpf_reg_types context_types = { .types = { PTR_TO_CTX } };
 static const struct bpf_reg_types ringbuf_mem_types = { .types = { PTR_TO_MEM | MEM_RINGBUF } };
 static const struct bpf_reg_types const_map_ptr_types = { .types = { CONST_PTR_TO_MAP } };
 static const struct bpf_reg_types btf_ptr_types = {
         .types = {
                 PTR_TO_BTF_ID,
                 PTR_TO_BTF_ID | PTR_TRUSTED,
                 PTR_TO_BTF_ID | MEM_RCU,
         },
 };
 static const struct bpf_reg_types percpu_btf_ptr_types = {
         .types = {
                 PTR_TO_BTF_ID | MEM_PERCPU,
                 PTR_TO_BTF_ID | MEM_PERCPU | MEM_RCU,
                 PTR_TO_BTF_ID | MEM_PERCPU | PTR_TRUSTED,
         }
 };
 static const struct bpf_reg_types func_ptr_types = { .types = { PTR_TO_FUNC } };
 static const struct bpf_reg_types stack_ptr_types = { .types = { PTR_TO_STACK } };
 static const struct bpf_reg_types const_str_ptr_types = { .types = { PTR_TO_MAP_VALUE } };
 static const struct bpf_reg_types timer_types = { .types = { PTR_TO_MAP_VALUE } };
 static const struct bpf_reg_types kptr_types = { .types = { PTR_TO_MAP_VALUE } };
 static const struct bpf_reg_types dynptr_types = {
         .types = {
                 PTR_TO_STACK,
                 CONST_PTR_TO_DYNPTR,
         }
 };
 
 static const struct bpf_reg_types *compatible_reg_types[__BPF_ARG_TYPE_MAX] = {
         [ARG_PTR_TO_MAP_KEY]            = &mem_types,
         [ARG_PTR_TO_MAP_VALUE]          = &mem_types,
         [ARG_CONST_SIZE]                = &scalar_types,
         [ARG_CONST_SIZE_OR_ZERO]        = &scalar_types,
         [ARG_CONST_ALLOC_SIZE_OR_ZERO]  = &scalar_types,
         [ARG_CONST_MAP_PTR]             = &const_map_ptr_types,
         [ARG_PTR_TO_CTX]                = &context_types,
         [ARG_PTR_TO_SOCK_COMMON]        = &sock_types,
 #ifdef CONFIG_NET
         [ARG_PTR_TO_BTF_ID_SOCK_COMMON] = &btf_id_sock_common_types,
 #endif
         [ARG_PTR_TO_SOCKET]             = &fullsock_types,
         [ARG_PTR_TO_BTF_ID]             = &btf_ptr_types,
         [ARG_PTR_TO_SPIN_LOCK]          = &spin_lock_types,
         [ARG_PTR_TO_MEM]                = &mem_types,
         [ARG_PTR_TO_RINGBUF_MEM]        = &ringbuf_mem_types,
         [ARG_PTR_TO_PERCPU_BTF_ID]      = &percpu_btf_ptr_types,
         [ARG_PTR_TO_FUNC]               = &func_ptr_types,
         [ARG_PTR_TO_STACK]              = &stack_ptr_types,
         [ARG_PTR_TO_CONST_STR]          = &const_str_ptr_types,
         [ARG_PTR_TO_TIMER]              = &timer_types,
         [ARG_PTR_TO_KPTR]               = &kptr_types,
         [ARG_PTR_TO_DYNPTR]             = &dynptr_types,
 };
 
 static int check_reg_type(struct bpf_verifier_env *env, u32 regno,
                           enum bpf_arg_type arg_type,
                           const u32 *arg_btf_id,
                           struct bpf_call_arg_meta *meta)
 {
         struct bpf_reg_state *regs = cur_regs(env), *reg = &regs[regno];
         enum bpf_reg_type expected, type = reg->type;
         const struct bpf_reg_types *compatible;
         int i, j;
 
         compatible = compatible_reg_types[base_type(arg_type)];
         if (!compatible) {
                 verbose(env, "verifier internal error: unsupported arg type %d\n", arg_type);
                 return -EFAULT;
         }
 
         /* ARG_PTR_TO_MEM + RDONLY is compatible with PTR_TO_MEM and PTR_TO_MEM + RDONLY,
          * but ARG_PTR_TO_MEM is compatible only with PTR_TO_MEM and NOT with PTR_TO_MEM + RDONLY
          *
          * Same for MAYBE_NULL:
          *
          * ARG_PTR_TO_MEM + MAYBE_NULL is compatible with PTR_TO_MEM and PTR_TO_MEM + MAYBE_NULL,
          * but ARG_PTR_TO_MEM is compatible only with PTR_TO_MEM but NOT with PTR_TO_MEM + MAYBE_NULL
          *
          * ARG_PTR_TO_MEM is compatible with PTR_TO_MEM that is tagged with a dynptr type.
          *
          * Therefore we fold these flags depending on the arg_type before comparison.
          */
         if (arg_type & MEM_RDONLY)
                 type &= ~MEM_RDONLY;
         if (arg_type & PTR_MAYBE_NULL)
                 type &= ~PTR_MAYBE_NULL;
         if (base_type(arg_type) == ARG_PTR_TO_MEM)
                 type &= ~DYNPTR_TYPE_FLAG_MASK;
 
         if (meta->func_id == BPF_FUNC_kptr_xchg && type_is_alloc(type)) {
                 type &= ~MEM_ALLOC;
                 type &= ~MEM_PERCPU;
         }
 
         for (i = 0; i < ARRAY_SIZE(compatible->types); i++) {
                 expected = compatible->types[i];
                 if (expected == NOT_INIT)
                         break;
 
                 if (type == expected)
                         goto found;
         }
 
         verbose(env, "R%d type=%s expected=", regno, reg_type_str(env, reg->type));
         for (j = 0; j + 1 < i; j++)
                 verbose(env, "%s, ", reg_type_str(env, compatible->types[j]));
         verbose(env, "%s\n", reg_type_str(env, compatible->types[j]));
         return -EACCES;
 
 found:
         if (base_type(reg->type) != PTR_TO_BTF_ID)
                 return 0;
 
         if (compatible == &mem_types) {
                 if (!(arg_type & MEM_RDONLY)) {
                         verbose(env,
                                 "%s() may write into memory pointed by R%d type=%s\n",
                                 func_id_name(meta->func_id),
                                 regno, reg_type_str(env, reg->type));
                         return -EACCES;
                 }
                 return 0;
         }
 
         switch ((int)reg->type) {
         case PTR_TO_BTF_ID:
         case PTR_TO_BTF_ID | PTR_TRUSTED:
         case PTR_TO_BTF_ID | PTR_TRUSTED | PTR_MAYBE_NULL:
         case PTR_TO_BTF_ID | MEM_RCU:
         case PTR_TO_BTF_ID | PTR_MAYBE_NULL:
         case PTR_TO_BTF_ID | PTR_MAYBE_NULL | MEM_RCU:
         {
                 /* For bpf_sk_release, it needs to match against first member
                  * 'struct sock_common', hence make an exception for it. This
                  * allows bpf_sk_release to work for multiple socket types.
                  */
                 bool strict_type_match = arg_type_is_release(arg_type) &&
                                          meta->func_id != BPF_FUNC_sk_release;
 
                 if (type_may_be_null(reg->type) &&
                     (!type_may_be_null(arg_type) || arg_type_is_release(arg_type))) {
                         verbose(env, "Possibly NULL pointer passed to helper arg%d\n", regno);
                         return -EACCES;
                 }
 
                 if (!arg_btf_id) {
                         if (!compatible->btf_id) {
                                 verbose(env, "verifier internal error: missing arg compatible BTF ID\n");
                                 return -EFAULT;
                         }
                         arg_btf_id = compatible->btf_id;
                 }
 
                 if (meta->func_id == BPF_FUNC_kptr_xchg) {
                         if (map_kptr_match_type(env, meta->kptr_field, reg, regno))
                                 return -EACCES;
                 } else {
                         if (arg_btf_id == BPF_PTR_POISON) {
                                 verbose(env, "verifier internal error:");
                                 verbose(env, "R%d has non-overwritten BPF_PTR_POISON type\n",
                                         regno);
                                 return -EACCES;
                         }
 
                         if (!btf_struct_ids_match(&env->log, reg->btf, reg->btf_id, reg->off,
                                                   btf_vmlinux, *arg_btf_id,
                                                   strict_type_match)) {
                                 verbose(env, "R%d is of type %s but %s is expected\n",
                                         regno, btf_type_name(reg->btf, reg->btf_id),
                                         btf_type_name(btf_vmlinux, *arg_btf_id));
                                 return -EACCES;
                         }
                 }
                 break;
         }
         case PTR_TO_BTF_ID | MEM_ALLOC:
         case PTR_TO_BTF_ID | MEM_PERCPU | MEM_ALLOC:
                 if (meta->func_id != BPF_FUNC_spin_lock && meta->func_id != BPF_FUNC_spin_unlock &&
                     meta->func_id != BPF_FUNC_kptr_xchg) {
                         verbose(env, "verifier internal error: unimplemented handling of MEM_ALLOC\n");
                         return -EFAULT;
                 }
                 if (meta->func_id == BPF_FUNC_kptr_xchg) {
                         if (map_kptr_match_type(env, meta->kptr_field, reg, regno))
                                 return -EACCES;
                 }
                 break;
         case PTR_TO_BTF_ID | MEM_PERCPU:
         case PTR_TO_BTF_ID | MEM_PERCPU | MEM_RCU:
         case PTR_TO_BTF_ID | MEM_PERCPU | PTR_TRUSTED:
                 /* Handled by helper specific checks */
                 break;
         default:
                 verbose(env, "verifier internal error: invalid PTR_TO_BTF_ID register for type match\n");
                 return -EFAULT;
         }
         return 0;
 }
 
 static struct btf_field *
 reg_find_field_offset(const struct bpf_reg_state *reg, s32 off, u32 fields)
 {
         struct btf_field *field;
         struct btf_record *rec;
 
         rec = reg_btf_record(reg);
         if (!rec)
                 return NULL;
 
         field = btf_record_find(rec, off, fields);
         if (!field)
                 return NULL;
 
         return field;
 }
 
 static int check_func_arg_reg_off(struct bpf_verifier_env *env,
                                   const struct bpf_reg_state *reg, int regno,
                                   enum bpf_arg_type arg_type)
 {
         u32 type = reg->type;
 
         /* When referenced register is passed to release function, its fixed
          * offset must be 0.
          *
          * We will check arg_type_is_release reg has ref_obj_id when storing
          * meta->release_regno.
          */
         if (arg_type_is_release(arg_type)) {
                 /* ARG_PTR_TO_DYNPTR with OBJ_RELEASE is a bit special, as it
                  * may not directly point to the object being released, but to
                  * dynptr pointing to such object, which might be at some offset
                  * on the stack. In that case, we simply to fallback to the
                  * default handling.
                  */
                 if (arg_type_is_dynptr(arg_type) && type == PTR_TO_STACK)
                         return 0;
 
                 /* Doing check_ptr_off_reg check for the offset will catch this
                  * because fixed_off_ok is false, but checking here allows us
                  * to give the user a better error message.
                  */
                 if (reg->off) {
                         verbose(env, "R%d must have zero offset when passed to release func or trusted arg to kfunc\n",
                                 regno);
                         return -EINVAL;
                 }
                 return __check_ptr_off_reg(env, reg, regno, false);
         }
 
         switch (type) {
         /* Pointer types where both fixed and variable offset is explicitly allowed: */
         case PTR_TO_STACK:
         case PTR_TO_PACKET:
         case PTR_TO_PACKET_META:
         case PTR_TO_MAP_KEY:
         case PTR_TO_MAP_VALUE:
         case PTR_TO_MEM:
         case PTR_TO_MEM | MEM_RDONLY:
         case PTR_TO_MEM | MEM_RINGBUF:
         case PTR_TO_BUF:
         case PTR_TO_BUF | MEM_RDONLY:
         case PTR_TO_ARENA:
         case SCALAR_VALUE:
                 return 0;
         /* All the rest must be rejected, except PTR_TO_BTF_ID which allows
          * fixed offset.
          */
         case PTR_TO_BTF_ID:
         case PTR_TO_BTF_ID | MEM_ALLOC:
         case PTR_TO_BTF_ID | PTR_TRUSTED:
         case PTR_TO_BTF_ID | MEM_RCU:
         case PTR_TO_BTF_ID | MEM_ALLOC | NON_OWN_REF:
         case PTR_TO_BTF_ID | MEM_ALLOC | NON_OWN_REF | MEM_RCU:
                 /* When referenced PTR_TO_BTF_ID is passed to release function,
                  * its fixed offset must be 0. In the other cases, fixed offset
                  * can be non-zero. This was already checked above. So pass
                  * fixed_off_ok as true to allow fixed offset for all other
                  * cases. var_off always must be 0 for PTR_TO_BTF_ID, hence we
                  * still need to do checks instead of returning.
                  */
                 return __check_ptr_off_reg(env, reg, regno, true);
         default:
                 return __check_ptr_off_reg(env, reg, regno, false);
         }
 }
 
 static struct bpf_reg_state *get_dynptr_arg_reg(struct bpf_verifier_env *env,
                                                 const struct bpf_func_proto *fn,
                                                 struct bpf_reg_state *regs)
 {
         struct bpf_reg_state *state = NULL;
         int i;
 
         for (i = 0; i < MAX_BPF_FUNC_REG_ARGS; i++)
                 if (arg_type_is_dynptr(fn->arg_type[i])) {
                         if (state) {
                                 verbose(env, "verifier internal error: multiple dynptr args\n");
                                 return NULL;
                         }
                         state = &regs[BPF_REG_1 + i];
                 }
 
         if (!state)
                 verbose(env, "verifier internal error: no dynptr arg found\n");
 
         return state;
 }
 
 static int dynptr_id(struct bpf_verifier_env *env, struct bpf_reg_state *reg)
 {
         struct bpf_func_state *state = func(env, reg);
         int spi;
 
         if (reg->type == CONST_PTR_TO_DYNPTR)
                 return reg->id;
         spi = dynptr_get_spi(env, reg);
         if (spi < 0)
                 return spi;
         return state->stack[spi].spilled_ptr.id;
 }
 
 static int dynptr_ref_obj_id(struct bpf_verifier_env *env, struct bpf_reg_state *reg)
 {
         struct bpf_func_state *state = func(env, reg);
         int spi;
 
         if (reg->type == CONST_PTR_TO_DYNPTR)
                 return reg->ref_obj_id;
         spi = dynptr_get_spi(env, reg);
         if (spi < 0)
                 return spi;
         return state->stack[spi].spilled_ptr.ref_obj_id;
 }
 
 static enum bpf_dynptr_type dynptr_get_type(struct bpf_verifier_env *env,
                                             struct bpf_reg_state *reg)
 {
         struct bpf_func_state *state = func(env, reg);
         int spi;
 
         if (reg->type == CONST_PTR_TO_DYNPTR)
                 return reg->dynptr.type;
 
         spi = __get_spi(reg->off);
         if (spi < 0) {
                 verbose(env, "verifier internal error: invalid spi when querying dynptr type\n");
                 return BPF_DYNPTR_TYPE_INVALID;
         }
 
         return state->stack[spi].spilled_ptr.dynptr.type;
 }
 
 static int check_reg_const_str(struct bpf_verifier_env *env,
                                struct bpf_reg_state *reg, u32 regno)
 {
         struct bpf_map *map = reg->map_ptr;
         int err;
         int map_off;
         u64 map_addr;
         char *str_ptr;
 
         if (reg->type != PTR_TO_MAP_VALUE)
                 return -EINVAL;
 
         if (!bpf_map_is_rdonly(map)) {
                 verbose(env, "R%d does not point to a readonly map'\n", regno);
                 return -EACCES;
         }
 
         if (!tnum_is_const(reg->var_off)) {
                 verbose(env, "R%d is not a constant address'\n", regno);
                 return -EACCES;
         }
 
         if (!map->ops->map_direct_value_addr) {
                 verbose(env, "no direct value access support for this map type\n");
                 return -EACCES;
         }
 
         err = check_map_access(env, regno, reg->off,
                                map->value_size - reg->off, false,
                                ACCESS_HELPER);
         if (err)
                 return err;
 
         map_off = reg->off + reg->var_off.value;
         err = map->ops->map_direct_value_addr(map, &map_addr, map_off);
         if (err) {
                 verbose(env, "direct value access on string failed\n");
                 return err;
         }
 
         str_ptr = (char *)(long)(map_addr);
         if (!strnchr(str_ptr + map_off, map->value_size - map_off, 0)) {
                 verbose(env, "string is not zero-terminated\n");
                 return -EINVAL;
         }
         return 0;
 }
 
 static int check_func_arg(struct bpf_verifier_env *env, u32 arg,
                           struct bpf_call_arg_meta *meta,
                           const struct bpf_func_proto *fn,
                           int insn_idx)
 {
         u32 regno = BPF_REG_1 + arg;
         struct bpf_reg_state *regs = cur_regs(env), *reg = &regs[regno];
         enum bpf_arg_type arg_type = fn->arg_type[arg];
         enum bpf_reg_type type = reg->type;
         u32 *arg_btf_id = NULL;
         int err = 0;
 
         if (arg_type == ARG_DONTCARE)
                 return 0;
 
         err = check_reg_arg(env, regno, SRC_OP);
         if (err)
                 return err;
 
         if (arg_type == ARG_ANYTHING) {
                 if (is_pointer_value(env, regno)) {
                         verbose(env, "R%d leaks addr into helper function\n",
                                 regno);
                         return -EACCES;
                 }
                 return 0;
         }
 
         if (type_is_pkt_pointer(type) &&
             !may_access_direct_pkt_data(env, meta, BPF_READ)) {
                 verbose(env, "helper access to the packet is not allowed\n");
                 return -EACCES;
         }
 
         if (base_type(arg_type) == ARG_PTR_TO_MAP_VALUE) {
                 err = resolve_map_arg_type(env, meta, &arg_type);
                 if (err)
                         return err;
         }
 
         if (register_is_null(reg) && type_may_be_null(arg_type))
                 /* A NULL register has a SCALAR_VALUE type, so skip
                  * type checking.
                  */
                 goto skip_type_check;
 
         /* arg_btf_id and arg_size are in a union. */
         if (base_type(arg_type) == ARG_PTR_TO_BTF_ID ||
             base_type(arg_type) == ARG_PTR_TO_SPIN_LOCK)
                 arg_btf_id = fn->arg_btf_id[arg];
 
         err = check_reg_type(env, regno, arg_type, arg_btf_id, meta);
         if (err)
                 return err;
 
         err = check_func_arg_reg_off(env, reg, regno, arg_type);
         if (err)
                 return err;
 
 skip_type_check:
         if (arg_type_is_release(arg_type)) {
                 if (arg_type_is_dynptr(arg_type)) {
                         struct bpf_func_state *state = func(env, reg);
                         int spi;
 
                         /* Only dynptr created on stack can be released, thus
                          * the get_spi and stack state checks for spilled_ptr
                          * should only be done before process_dynptr_func for
                          * PTR_TO_STACK.
                          */
                         if (reg->type == PTR_TO_STACK) {
                                 spi = dynptr_get_spi(env, reg);
                                 if (spi < 0 || !state->stack[spi].spilled_ptr.ref_obj_id) {
                                         verbose(env, "arg %d is an unacquired reference\n", regno);
                                         return -EINVAL;
                                 }
                         } else {
                                 verbose(env, "cannot release unowned const bpf_dynptr\n");
                                 return -EINVAL;
                         }
                 } else if (!reg->ref_obj_id && !register_is_null(reg)) {
                         verbose(env, "R%d must be referenced when passed to release function\n",
                                 regno);
                         return -EINVAL;
                 }
                 if (meta->release_regno) {
                         verbose(env, "verifier internal error: more than one release argument\n");
                         return -EFAULT;
                 }
                 meta->release_regno = regno;
         }
 
         if (reg->ref_obj_id) {
                 if (meta->ref_obj_id) {
                         verbose(env, "verifier internal error: more than one arg with ref_obj_id R%d %u %u\n",
                                 regno, reg->ref_obj_id,
                                 meta->ref_obj_id);
                         return -EFAULT;
                 }
                 meta->ref_obj_id = reg->ref_obj_id;
         }
 
         switch (base_type(arg_type)) {
         case ARG_CONST_MAP_PTR:
                 /* bpf_map_xxx(map_ptr) call: remember that map_ptr */
                 if (meta->map_ptr) {
                         /* Use map_uid (which is unique id of inner map) to reject:
                          * inner_map1 = bpf_map_lookup_elem(outer_map, key1)
                          * inner_map2 = bpf_map_lookup_elem(outer_map, key2)
                          * if (inner_map1 && inner_map2) {
                          *     timer = bpf_map_lookup_elem(inner_map1);
                          *     if (timer)
                          *         // mismatch would have been allowed
                          *         bpf_timer_init(timer, inner_map2);
                          * }
                          *
                          * Comparing map_ptr is enough to distinguish normal and outer maps.
                          */
                         if (meta->map_ptr != reg->map_ptr ||
                             meta->map_uid != reg->map_uid) {
                                 verbose(env,
                                         "timer pointer in R1 map_uid=%d doesn't match map pointer in R2 map_uid=%d\n",
                                         meta->map_uid, reg->map_uid);
                                 return -EINVAL;
                         }
                 }
                 meta->map_ptr = reg->map_ptr;
                 meta->map_uid = reg->map_uid;
                 break;
         case ARG_PTR_TO_MAP_KEY:
                 /* bpf_map_xxx(..., map_ptr, ..., key) call:
                  * check that [key, key + map->key_size) are within
                  * stack limits and initialized
                  */
                 if (!meta->map_ptr) {
                         /* in function declaration map_ptr must come before
                          * map_key, so that it's verified and known before
                          * we have to check map_key here. Otherwise it means
                          * that kernel subsystem misconfigured verifier
                          */
                         verbose(env, "invalid map_ptr to access map->key\n");
                         return -EACCES;
                 }
                 err = check_helper_mem_access(env, regno,
                                               meta->map_ptr->key_size, false,
                                               NULL);
                 break;
         case ARG_PTR_TO_MAP_VALUE:
                 if (type_may_be_null(arg_type) && register_is_null(reg))
                         return 0;
 
                 /* bpf_map_xxx(..., map_ptr, ..., value) call:
                  * check [value, value + map->value_size) validity
                  */
                 if (!meta->map_ptr) {
                         /* kernel subsystem misconfigured verifier */
                         verbose(env, "invalid map_ptr to access map->value\n");
                         return -EACCES;
                 }
                 meta->raw_mode = arg_type & MEM_UNINIT;
                 err = check_helper_mem_access(env, regno,
                                               meta->map_ptr->value_size, false,
                                               meta);
                 break;
         case ARG_PTR_TO_PERCPU_BTF_ID:
                 if (!reg->btf_id) {
                         verbose(env, "Helper has invalid btf_id in R%d\n", regno);
                         return -EACCES;
                 }
                 meta->ret_btf = reg->btf;
                 meta->ret_btf_id = reg->btf_id;
                 break;
         case ARG_PTR_TO_SPIN_LOCK:
                 if (in_rbtree_lock_required_cb(env)) {
                         verbose(env, "can't spin_{lock,unlock} in rbtree cb\n");
                         return -EACCES;
                 }
                 if (meta->func_id == BPF_FUNC_spin_lock) {
                         err = process_spin_lock(env, regno, true);
                         if (err)
                                 return err;
                 } else if (meta->func_id == BPF_FUNC_spin_unlock) {
                         err = process_spin_lock(env, regno, false);
                         if (err)
                                 return err;
                 } else {
                         verbose(env, "verifier internal error\n");
                         return -EFAULT;
                 }
                 break;
         case ARG_PTR_TO_TIMER:
                 err = process_timer_func(env, regno, meta);
                 if (err)
                         return err;
                 break;
         case ARG_PTR_TO_FUNC:
                 meta->subprogno = reg->subprogno;
                 break;
         case ARG_PTR_TO_MEM:
                 /* The access to this pointer is only checked when we hit the
                  * next is_mem_size argument below.
                  */
                 meta->raw_mode = arg_type & MEM_UNINIT;
                 if (arg_type & MEM_FIXED_SIZE) {
                         err = check_helper_mem_access(env, regno, fn->arg_size[arg], false, meta);
                         if (err)
                                 return err;
                         if (arg_type & MEM_ALIGNED)
                                 err = check_ptr_alignment(env, reg, 0, fn->arg_size[arg], true);
                 }
                 break;
         case ARG_CONST_SIZE:
                 err = check_mem_size_reg(env, reg, regno, false, meta);
                 break;
         case ARG_CONST_SIZE_OR_ZERO:
                 err = check_mem_size_reg(env, reg, regno, true, meta);
                 break;
         case ARG_PTR_TO_DYNPTR:
                 err = process_dynptr_func(env, regno, insn_idx, arg_type, 0);
                 if (err)
                         return err;
                 break;
         case ARG_CONST_ALLOC_SIZE_OR_ZERO:
                 if (!tnum_is_const(reg->var_off)) {
                         verbose(env, "R%d is not a known constant'\n",
                                 regno);
                         return -EACCES;
                 }
                 meta->mem_size = reg->var_off.value;
                 err = mark_chain_precision(env, regno);
                 if (err)
                         return err;
                 break;
         case ARG_PTR_TO_CONST_STR:
         {
                 err = check_reg_const_str(env, reg, regno);
                 if (err)
                         return err;
                 break;
         }
         case ARG_PTR_TO_KPTR:
                 err = process_kptr_func(env, regno, meta);
                 if (err)
                         return err;
                 break;
         }
 
         return err;
 }
 
 static bool may_update_sockmap(struct bpf_verifier_env *env, int func_id)
 {
         enum bpf_attach_type eatype = env->prog->expected_attach_type;
         enum bpf_prog_type type = resolve_prog_type(env->prog);
 
         if (func_id != BPF_FUNC_map_update_elem &&
             func_id != BPF_FUNC_map_delete_elem)
                 return false;
 
         /* It's not possible to get access to a locked struct sock in these
          * contexts, so updating is safe.
          */
         switch (type) {
         case BPF_PROG_TYPE_TRACING:
                 if (eatype == BPF_TRACE_ITER)
                         return true;
                 break;
         case BPF_PROG_TYPE_SOCK_OPS:
                 /* map_update allowed only via dedicated helpers with event type checks */
                 if (func_id == BPF_FUNC_map_delete_elem)
                         return true;
                 break;
         case BPF_PROG_TYPE_SOCKET_FILTER:
         case BPF_PROG_TYPE_SCHED_CLS:
         case BPF_PROG_TYPE_SCHED_ACT:
         case BPF_PROG_TYPE_XDP:
         case BPF_PROG_TYPE_SK_REUSEPORT:
         case BPF_PROG_TYPE_FLOW_DISSECTOR:
         case BPF_PROG_TYPE_SK_LOOKUP:
                 return true;
         default:
                 break;
         }
 
         verbose(env, "cannot update sockmap in this context\n");
         return false;
 }
 
 static bool allow_tail_call_in_subprogs(struct bpf_verifier_env *env)
 {
         return env->prog->jit_requested &&
                bpf_jit_supports_subprog_tailcalls();
 }
 
 static int check_map_func_compatibility(struct bpf_verifier_env *env,
                                         struct bpf_map *map, int func_id)
 {
         if (!map)
                 return 0;
 
         /* We need a two way check, first is from map perspective ... */
         switch (map->map_type) {
         case BPF_MAP_TYPE_PROG_ARRAY:
                 if (func_id != BPF_FUNC_tail_call)
                         goto error;
                 break;
         case BPF_MAP_TYPE_PERF_EVENT_ARRAY:
                 if (func_id != BPF_FUNC_perf_event_read &&
                     func_id != BPF_FUNC_perf_event_output &&
                     func_id != BPF_FUNC_skb_output &&
                     func_id != BPF_FUNC_perf_event_read_value &&
                     func_id != BPF_FUNC_xdp_output)
                         goto error;
                 break;
         case BPF_MAP_TYPE_RINGBUF:
                 if (func_id != BPF_FUNC_ringbuf_output &&
                     func_id != BPF_FUNC_ringbuf_reserve &&
                     func_id != BPF_FUNC_ringbuf_query &&
                     func_id != BPF_FUNC_ringbuf_reserve_dynptr &&
                     func_id != BPF_FUNC_ringbuf_submit_dynptr &&
                     func_id != BPF_FUNC_ringbuf_discard_dynptr)
                         goto error;
                 break;
         case BPF_MAP_TYPE_USER_RINGBUF:
                 if (func_id != BPF_FUNC_user_ringbuf_drain)
                         goto error;
                 break;
         case BPF_MAP_TYPE_STACK_TRACE:
                 if (func_id != BPF_FUNC_get_stackid)
                         goto error;
                 break;
         case BPF_MAP_TYPE_CGROUP_ARRAY:
                 if (func_id != BPF_FUNC_skb_under_cgroup &&
                     func_id != BPF_FUNC_current_task_under_cgroup)
                         goto error;
                 break;
         case BPF_MAP_TYPE_CGROUP_STORAGE:
         case BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE:
                 if (func_id != BPF_FUNC_get_local_storage)
                         goto error;
                 break;
         case BPF_MAP_TYPE_DEVMAP:
         case BPF_MAP_TYPE_DEVMAP_HASH:
                 if (func_id != BPF_FUNC_redirect_map &&
                     func_id != BPF_FUNC_map_lookup_elem)
                         goto error;
                 break;
         /* Restrict bpf side of cpumap and xskmap, open when use-cases
          * appear.
          */
         case BPF_MAP_TYPE_CPUMAP:
                 if (func_id != BPF_FUNC_redirect_map)
                         goto error;
                 break;
         case BPF_MAP_TYPE_XSKMAP:
                 if (func_id != BPF_FUNC_redirect_map &&
                     func_id != BPF_FUNC_map_lookup_elem)
                         goto error;
                 break;
         case BPF_MAP_TYPE_ARRAY_OF_MAPS:
         case BPF_MAP_TYPE_HASH_OF_MAPS:
                 if (func_id != BPF_FUNC_map_lookup_elem)
                         goto error;
                 break;
         case BPF_MAP_TYPE_SOCKMAP:
                 if (func_id != BPF_FUNC_sk_redirect_map &&
                     func_id != BPF_FUNC_sock_map_update &&
                     func_id != BPF_FUNC_msg_redirect_map &&
                     func_id != BPF_FUNC_sk_select_reuseport &&
                     func_id != BPF_FUNC_map_lookup_elem &&
                     !may_update_sockmap(env, func_id))
                         goto error;
                 break;
         case BPF_MAP_TYPE_SOCKHASH:
                 if (func_id != BPF_FUNC_sk_redirect_hash &&
                     func_id != BPF_FUNC_sock_hash_update &&
                     func_id != BPF_FUNC_msg_redirect_hash &&
                     func_id != BPF_FUNC_sk_select_reuseport &&
                     func_id != BPF_FUNC_map_lookup_elem &&
                     !may_update_sockmap(env, func_id))
                         goto error;
                 break;
         case BPF_MAP_TYPE_REUSEPORT_SOCKARRAY:
                 if (func_id != BPF_FUNC_sk_select_reuseport)
                         goto error;
                 break;
         case BPF_MAP_TYPE_QUEUE:
         case BPF_MAP_TYPE_STACK:
                 if (func_id != BPF_FUNC_map_peek_elem &&
                     func_id != BPF_FUNC_map_pop_elem &&
                     func_id != BPF_FUNC_map_push_elem)
                         goto error;
                 break;
         case BPF_MAP_TYPE_SK_STORAGE:
                 if (func_id != BPF_FUNC_sk_storage_get &&
                     func_id != BPF_FUNC_sk_storage_delete &&
                     func_id != BPF_FUNC_kptr_xchg)
                         goto error;
                 break;
         case BPF_MAP_TYPE_INODE_STORAGE:
                 if (func_id != BPF_FUNC_inode_storage_get &&
                     func_id != BPF_FUNC_inode_storage_delete &&
                     func_id != BPF_FUNC_kptr_xchg)
                         goto error;
                 break;
         case BPF_MAP_TYPE_TASK_STORAGE:
                 if (func_id != BPF_FUNC_task_storage_get &&
                     func_id != BPF_FUNC_task_storage_delete &&
                     func_id != BPF_FUNC_kptr_xchg)
                         goto error;
                 break;
         case BPF_MAP_TYPE_CGRP_STORAGE:
                 if (func_id != BPF_FUNC_cgrp_storage_get &&
                     func_id != BPF_FUNC_cgrp_storage_delete &&
                     func_id != BPF_FUNC_kptr_xchg)
                         goto error;
                 break;
         case BPF_MAP_TYPE_BLOOM_FILTER:
                 if (func_id != BPF_FUNC_map_peek_elem &&
                     func_id != BPF_FUNC_map_push_elem)
                         goto error;
                 break;
         default:
                 break;
         }
 
         /* ... and second from the function itself. */
         switch (func_id) {
         case BPF_FUNC_tail_call:
                 if (map->map_type != BPF_MAP_TYPE_PROG_ARRAY)
                         goto error;
                 if (env->subprog_cnt > 1 && !allow_tail_call_in_subprogs(env)) {
                         verbose(env, "tail_calls are not allowed in non-JITed programs with bpf-to-bpf calls\n");
                         return -EINVAL;
                 }
                 break;
         case BPF_FUNC_perf_event_read:
         case BPF_FUNC_perf_event_output:
         case BPF_FUNC_perf_event_read_value:
         case BPF_FUNC_skb_output:
         case BPF_FUNC_xdp_output:
                 if (map->map_type != BPF_MAP_TYPE_PERF_EVENT_ARRAY)
                         goto error;
                 break;
         case BPF_FUNC_ringbuf_output:
         case BPF_FUNC_ringbuf_reserve:
         case BPF_FUNC_ringbuf_query:
         case BPF_FUNC_ringbuf_reserve_dynptr:
         case BPF_FUNC_ringbuf_submit_dynptr:
         case BPF_FUNC_ringbuf_discard_dynptr:
                 if (map->map_type != BPF_MAP_TYPE_RINGBUF)
                         goto error;
                 break;
         case BPF_FUNC_user_ringbuf_drain:
                 if (map->map_type != BPF_MAP_TYPE_USER_RINGBUF)
                         goto error;
                 break;
         case BPF_FUNC_get_stackid:
                 if (map->map_type != BPF_MAP_TYPE_STACK_TRACE)
                         goto error;
                 break;
         case BPF_FUNC_current_task_under_cgroup:
         case BPF_FUNC_skb_under_cgroup:
                 if (map->map_type != BPF_MAP_TYPE_CGROUP_ARRAY)
                         goto error;
                 break;
         case BPF_FUNC_redirect_map:
                 if (map->map_type != BPF_MAP_TYPE_DEVMAP &&
                     map->map_type != BPF_MAP_TYPE_DEVMAP_HASH &&
                     map->map_type != BPF_MAP_TYPE_CPUMAP &&
                     map->map_type != BPF_MAP_TYPE_XSKMAP)
                         goto error;
                 break;
         case BPF_FUNC_sk_redirect_map:
         case BPF_FUNC_msg_redirect_map:
         case BPF_FUNC_sock_map_update:
                 if (map->map_type != BPF_MAP_TYPE_SOCKMAP)
                         goto error;
                 break;
         case BPF_FUNC_sk_redirect_hash:
         case BPF_FUNC_msg_redirect_hash:
         case BPF_FUNC_sock_hash_update:
                 if (map->map_type != BPF_MAP_TYPE_SOCKHASH)
                         goto error;
                 break;
         case BPF_FUNC_get_local_storage:
                 if (map->map_type != BPF_MAP_TYPE_CGROUP_STORAGE &&
                     map->map_type != BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE)
                         goto error;
                 break;
         case BPF_FUNC_sk_select_reuseport:
                 if (map->map_type != BPF_MAP_TYPE_REUSEPORT_SOCKARRAY &&
                     map->map_type != BPF_MAP_TYPE_SOCKMAP &&
                     map->map_type != BPF_MAP_TYPE_SOCKHASH)
                         goto error;
                 break;
         case BPF_FUNC_map_pop_elem:
                 if (map->map_type != BPF_MAP_TYPE_QUEUE &&
                     map->map_type != BPF_MAP_TYPE_STACK)
                         goto error;
                 break;
         case BPF_FUNC_map_peek_elem:
         case BPF_FUNC_map_push_elem:
                 if (map->map_type != BPF_MAP_TYPE_QUEUE &&
                     map->map_type != BPF_MAP_TYPE_STACK &&
                     map->map_type != BPF_MAP_TYPE_BLOOM_FILTER)
                         goto error;
                 break;
         case BPF_FUNC_map_lookup_percpu_elem:
                 if (map->map_type != BPF_MAP_TYPE_PERCPU_ARRAY &&
                     map->map_type != BPF_MAP_TYPE_PERCPU_HASH &&
                     map->map_type != BPF_MAP_TYPE_LRU_PERCPU_HASH)
                         goto error;
                 break;
         case BPF_FUNC_sk_storage_get:
         case BPF_FUNC_sk_storage_delete:
                 if (map->map_type != BPF_MAP_TYPE_SK_STORAGE)
                         goto error;
                 break;
         case BPF_FUNC_inode_storage_get:
         case BPF_FUNC_inode_storage_delete:
                 if (map->map_type != BPF_MAP_TYPE_INODE_STORAGE)
                         goto error;
                 break;
         case BPF_FUNC_task_storage_get:
         case BPF_FUNC_task_storage_delete:
                 if (map->map_type != BPF_MAP_TYPE_TASK_STORAGE)
                         goto error;
                 break;
         case BPF_FUNC_cgrp_storage_get:
         case BPF_FUNC_cgrp_storage_delete:
                 if (map->map_type != BPF_MAP_TYPE_CGRP_STORAGE)
                         goto error;
                 break;
         default:
                 break;
         }
 
         return 0;
 error:
         verbose(env, "cannot pass map_type %d into func %s#%d\n",
                 map->map_type, func_id_name(func_id), func_id);
         return -EINVAL;
 }
 
 static bool check_raw_mode_ok(const struct bpf_func_proto *fn)
 {
         int count = 0;
 
         if (arg_type_is_raw_mem(fn->arg1_type))
                 count++;
         if (arg_type_is_raw_mem(fn->arg2_type))
                 count++;
         if (arg_type_is_raw_mem(fn->arg3_type))
                 count++;
         if (arg_type_is_raw_mem(fn->arg4_type))
                 count++;
         if (arg_type_is_raw_mem(fn->arg5_type))
                 count++;
 
         /* We only support one arg being in raw mode at the moment,
          * which is sufficient for the helper functions we have
          * right now.
          */
         return count <= 1;
 }
 
 static bool check_args_pair_invalid(const struct bpf_func_proto *fn, int arg)
 {
         bool is_fixed = fn->arg_type[arg] & MEM_FIXED_SIZE;
         bool has_size = fn->arg_size[arg] != 0;
         bool is_next_size = false;
 
         if (arg + 1 < ARRAY_SIZE(fn->arg_type))
                 is_next_size = arg_type_is_mem_size(fn->arg_type[arg + 1]);
 
         if (base_type(fn->arg_type[arg]) != ARG_PTR_TO_MEM)
                 return is_next_size;
 
         return has_size == is_next_size || is_next_size == is_fixed;
 }
 
 static bool check_arg_pair_ok(const struct bpf_func_proto *fn)
 {
         /* bpf_xxx(..., buf, len) call will access 'len'
          * bytes from memory 'buf'. Both arg types need
          * to be paired, so make sure there's no buggy
          * helper function specification.
          */
         if (arg_type_is_mem_size(fn->arg1_type) ||
             check_args_pair_invalid(fn, 0) ||
             check_args_pair_invalid(fn, 1) ||
             check_args_pair_invalid(fn, 2) ||
             check_args_pair_invalid(fn, 3) ||
             check_args_pair_invalid(fn, 4))
                 return false;
 
         return true;
 }
 
 static bool check_btf_id_ok(const struct bpf_func_proto *fn)
 {
         int i;
 
         for (i = 0; i < ARRAY_SIZE(fn->arg_type); i++) {
                 if (base_type(fn->arg_type[i]) == ARG_PTR_TO_BTF_ID)
                         return !!fn->arg_btf_id[i];
                 if (base_type(fn->arg_type[i]) == ARG_PTR_TO_SPIN_LOCK)
                         return fn->arg_btf_id[i] == BPF_PTR_POISON;
                 if (base_type(fn->arg_type[i]) != ARG_PTR_TO_BTF_ID && fn->arg_btf_id[i] &&
                     /* arg_btf_id and arg_size are in a union. */
                     (base_type(fn->arg_type[i]) != ARG_PTR_TO_MEM ||
                      !(fn->arg_type[i] & MEM_FIXED_SIZE)))
                         return false;
         }
 
         return true;
 }
 
 static int check_func_proto(const struct bpf_func_proto *fn, int func_id)
 {
         return check_raw_mode_ok(fn) &&
                check_arg_pair_ok(fn) &&
                check_btf_id_ok(fn) ? 0 : -EINVAL;
 }
 
 /* Packet data might have moved, any old PTR_TO_PACKET[_META,_END]
  * are now invalid, so turn them into unknown SCALAR_VALUE.
  *
  * This also applies to dynptr slices belonging to skb and xdp dynptrs,
  * since these slices point to packet data.
  */
 static void clear_all_pkt_pointers(struct bpf_verifier_env *env)
 {
         struct bpf_func_state *state;
         struct bpf_reg_state *reg;
 
         bpf_for_each_reg_in_vstate(env->cur_state, state, reg, ({
                 if (reg_is_pkt_pointer_any(reg) || reg_is_dynptr_slice_pkt(reg))
                         mark_reg_invalid(env, reg);
         }));
 }
 
 enum {
         AT_PKT_END = -1,
         BEYOND_PKT_END = -2,
 };
 
 static void mark_pkt_end(struct bpf_verifier_state *vstate, int regn, bool range_open)
 {
         struct bpf_func_state *state = vstate->frame[vstate->curframe];
         struct bpf_reg_state *reg = &state->regs[regn];
 
         if (reg->type != PTR_TO_PACKET)
                 /* PTR_TO_PACKET_META is not supported yet */
                 return;
 
         /* The 'reg' is pkt > pkt_end or pkt >= pkt_end.
          * How far beyond pkt_end it goes is unknown.
          * if (!range_open) it's the case of pkt >= pkt_end
          * if (range_open) it's the case of pkt > pkt_end
          * hence this pointer is at least 1 byte bigger than pkt_end
          */
         if (range_open)
                 reg->range = BEYOND_PKT_END;
         else
                 reg->range = AT_PKT_END;
 }
 
 /* The pointer with the specified id has released its reference to kernel
  * resources. Identify all copies of the same pointer and clear the reference.
  */
 static int release_reference(struct bpf_verifier_env *env,
                              int ref_obj_id)
 {
         struct bpf_func_state *state;
         struct bpf_reg_state *reg;
         int err;
 
         err = release_reference_state(cur_func(env), ref_obj_id);
         if (err)
                 return err;
 
         bpf_for_each_reg_in_vstate(env->cur_state, state, reg, ({
                 if (reg->ref_obj_id == ref_obj_id)
                         mark_reg_invalid(env, reg);
         }));
 
         return 0;
 }
 
 static void invalidate_non_owning_refs(struct bpf_verifier_env *env)
 {
         struct bpf_func_state *unused;
         struct bpf_reg_state *reg;
 
         bpf_for_each_reg_in_vstate(env->cur_state, unused, reg, ({
                 if (type_is_non_owning_ref(reg->type))
                         mark_reg_invalid(env, reg);
         }));
 }
 
 static void clear_caller_saved_regs(struct bpf_verifier_env *env,
                                     struct bpf_reg_state *regs)
 {
         int i;
 
         /* after the call registers r0 - r5 were scratched */
         for (i = 0; i < CALLER_SAVED_REGS; i++) {
                 mark_reg_not_init(env, regs, caller_saved[i]);
                 __check_reg_arg(env, regs, caller_saved[i], DST_OP_NO_MARK);
         }
 }
 
 typedef int (*set_callee_state_fn)(struct bpf_verifier_env *env,
                                    struct bpf_func_state *caller,
                                    struct bpf_func_state *callee,
                                    int insn_idx);
 
 static int set_callee_state(struct bpf_verifier_env *env,
                             struct bpf_func_state *caller,
                             struct bpf_func_state *callee, int insn_idx);
 
 static int setup_func_entry(struct bpf_verifier_env *env, int subprog, int callsite,
                             set_callee_state_fn set_callee_state_cb,
                             struct bpf_verifier_state *state)
 {
         struct bpf_func_state *caller, *callee;
         int err;
 
         if (state->curframe + 1 >= MAX_CALL_FRAMES) {
                 verbose(env, "the call stack of %d frames is too deep\n",
                         state->curframe + 2);
                 return -E2BIG;
         }
 
         if (state->frame[state->curframe + 1]) {
                 verbose(env, "verifier bug. Frame %d already allocated\n",
                         state->curframe + 1);
                 return -EFAULT;
         }
 
         caller = state->frame[state->curframe];
         callee = kzalloc(sizeof(*callee), GFP_KERNEL);
         if (!callee)
                 return -ENOMEM;
         state->frame[state->curframe + 1] = callee;
 
         /* callee cannot access r0, r6 - r9 for reading and has to write
          * into its own stack before reading from it.
          * callee can read/write into caller's stack
          */
         init_func_state(env, callee,
                         /* remember the callsite, it will be used by bpf_exit */
                         callsite,
                         state->curframe + 1 /* frameno within this callchain */,
                         subprog /* subprog number within this prog */);
         /* Transfer references to the callee */
         err = copy_reference_state(callee, caller);
         err = err ?: set_callee_state_cb(env, caller, callee, callsite);
         if (err)
                 goto err_out;
 
         /* only increment it after check_reg_arg() finished */
         state->curframe++;
 
         return 0;
 
 err_out:
         free_func_state(callee);
         state->frame[state->curframe + 1] = NULL;
         return err;
 }
 
 static int btf_check_func_arg_match(struct bpf_verifier_env *env, int subprog,
                                     const struct btf *btf,
                                     struct bpf_reg_state *regs)
 {
         struct bpf_subprog_info *sub = subprog_info(env, subprog);
         struct bpf_verifier_log *log = &env->log;
         u32 i;
         int ret;
 
         ret = btf_prepare_func_args(env, subprog);
         if (ret)
                 return ret;
 
         /* check that BTF function arguments match actual types that the
          * verifier sees.
          */
         for (i = 0; i < sub->arg_cnt; i++) {
                 u32 regno = i + 1;
                 struct bpf_reg_state *reg = &regs[regno];
                 struct bpf_subprog_arg_info *arg = &sub->args[i];
 
                 if (arg->arg_type == ARG_ANYTHING) {
                         if (reg->type != SCALAR_VALUE) {
                                 bpf_log(log, "R%d is not a scalar\n", regno);
                                 return -EINVAL;
                         }
                 } else if (arg->arg_type == ARG_PTR_TO_CTX) {
                         ret = check_func_arg_reg_off(env, reg, regno, ARG_DONTCARE);
                         if (ret < 0)
                                 return ret;
                         /* If function expects ctx type in BTF check that caller
                          * is passing PTR_TO_CTX.
                          */
                         if (reg->type != PTR_TO_CTX) {
                                 bpf_log(log, "arg#%d expects pointer to ctx\n", i);
                                 return -EINVAL;
                         }
                 } else if (base_type(arg->arg_type) == ARG_PTR_TO_MEM) {
                         ret = check_func_arg_reg_off(env, reg, regno, ARG_DONTCARE);
                         if (ret < 0)
                                 return ret;
                         if (check_mem_reg(env, reg, regno, arg->mem_size))
                                 return -EINVAL;
                         if (!(arg->arg_type & PTR_MAYBE_NULL) && (reg->type & PTR_MAYBE_NULL)) {
                                 bpf_log(log, "arg#%d is expected to be non-NULL\n", i);
                                 return -EINVAL;
                         }
                 } else if (base_type(arg->arg_type) == ARG_PTR_TO_ARENA) {
                         /*
                          * Can pass any value and the kernel won't crash, but
                          * only PTR_TO_ARENA or SCALAR make sense. Everything
                          * else is a bug in the bpf program. Point it out to
                          * the user at the verification time instead of
                          * run-time debug nightmare.
                          */
                         if (reg->type != PTR_TO_ARENA && reg->type != SCALAR_VALUE) {
                                 bpf_log(log, "R%d is not a pointer to arena or scalar.\n", regno);
                                 return -EINVAL;
                         }
                 } else if (arg->arg_type == (ARG_PTR_TO_DYNPTR | MEM_RDONLY)) {
                         ret = check_func_arg_reg_off(env, reg, regno, ARG_PTR_TO_DYNPTR);
                         if (ret)
                                 return ret;
 
                         ret = process_dynptr_func(env, regno, -1, arg->arg_type, 0);
                         if (ret)
                                 return ret;
                 } else if (base_type(arg->arg_type) == ARG_PTR_TO_BTF_ID) {
                         struct bpf_call_arg_meta meta;
                         int err;
 
                         if (register_is_null(reg) && type_may_be_null(arg->arg_type))
                                 continue;
 
                         memset(&meta, 0, sizeof(meta)); /* leave func_id as zero */
                         err = check_reg_type(env, regno, arg->arg_type, &arg->btf_id, &meta);
                         err = err ?: check_func_arg_reg_off(env, reg, regno, arg->arg_type);
                         if (err)
                                 return err;
                 } else {
                         bpf_log(log, "verifier bug: unrecognized arg#%d type %d\n",
                                 i, arg->arg_type);
                         return -EFAULT;
                 }
         }
 
         return 0;
 }
 
 /* Compare BTF of a function call with given bpf_reg_state.
  * Returns:
  * EFAULT - there is a verifier bug. Abort verification.
  * EINVAL - there is a type mismatch or BTF is not available.
  * 0 - BTF matches with what bpf_reg_state expects.
  * Only PTR_TO_CTX and SCALAR_VALUE states are recognized.
  */
 static int btf_check_subprog_call(struct bpf_verifier_env *env, int subprog,
                                   struct bpf_reg_state *regs)
 {
         struct bpf_prog *prog = env->prog;
         struct btf *btf = prog->aux->btf;
         u32 btf_id;
         int err;
 
         if (!prog->aux->func_info)
                 return -EINVAL;
 
         btf_id = prog->aux->func_info[subprog].type_id;
         if (!btf_id)
                 return -EFAULT;
 
         if (prog->aux->func_info_aux[subprog].unreliable)
                 return -EINVAL;
 
         err = btf_check_func_arg_match(env, subprog, btf, regs);
         /* Compiler optimizations can remove arguments from static functions
          * or mismatched type can be passed into a global function.
          * In such cases mark the function as unreliable from BTF point of view.
          */
         if (err)
                 prog->aux->func_info_aux[subprog].unreliable = true;
         return err;
 }
 
 static int push_callback_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
                               int insn_idx, int subprog,
                               set_callee_state_fn set_callee_state_cb)
 {
         struct bpf_verifier_state *state = env->cur_state, *callback_state;
         struct bpf_func_state *caller, *callee;
         int err;
 
         caller = state->frame[state->curframe];
         err = btf_check_subprog_call(env, subprog, caller->regs);
         if (err == -EFAULT)
                 return err;
 
         /* set_callee_state is used for direct subprog calls, but we are
          * interested in validating only BPF helpers that can call subprogs as
          * callbacks
          */
         env->subprog_info[subprog].is_cb = true;
         if (bpf_pseudo_kfunc_call(insn) &&
             !is_callback_calling_kfunc(insn->imm)) {
                 verbose(env, "verifier bug: kfunc %s#%d not marked as callback-calling\n",
                         func_id_name(insn->imm), insn->imm);
                 return -EFAULT;
         } else if (!bpf_pseudo_kfunc_call(insn) &&
                    !is_callback_calling_function(insn->imm)) { /* helper */
                 verbose(env, "verifier bug: helper %s#%d not marked as callback-calling\n",
                         func_id_name(insn->imm), insn->imm);
                 return -EFAULT;
         }
 
         if (is_async_callback_calling_insn(insn)) {
                 struct bpf_verifier_state *async_cb;
 
                 /* there is no real recursion here. timer and workqueue callbacks are async */
                 env->subprog_info[subprog].is_async_cb = true;
                 async_cb = push_async_cb(env, env->subprog_info[subprog].start,
                                          insn_idx, subprog,
                                          is_bpf_wq_set_callback_impl_kfunc(insn->imm));
                 if (!async_cb)
                         return -EFAULT;
                 callee = async_cb->frame[0];
                 callee->async_entry_cnt = caller->async_entry_cnt + 1;
 
                 /* Convert bpf_timer_set_callback() args into timer callback args */
                 err = set_callee_state_cb(env, caller, callee, insn_idx);
                 if (err)
                         return err;
 
                 return 0;
         }
 
         /* for callback functions enqueue entry to callback and
          * proceed with next instruction within current frame.
          */
         callback_state = push_stack(env, env->subprog_info[subprog].start, insn_idx, false);
         if (!callback_state)
                 return -ENOMEM;
 
         err = setup_func_entry(env, subprog, insn_idx, set_callee_state_cb,
                                callback_state);
         if (err)
                 return err;
 
         callback_state->callback_unroll_depth++;
         callback_state->frame[callback_state->curframe - 1]->callback_depth++;
         caller->callback_depth = 0;
         return 0;
 }
 
 static int check_func_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
                            int *insn_idx)
 {
         struct bpf_verifier_state *state = env->cur_state;
         struct bpf_func_state *caller;
         int err, subprog, target_insn;
 
         target_insn = *insn_idx + insn->imm + 1;
         subprog = find_subprog(env, target_insn);
         if (subprog < 0) {
                 verbose(env, "verifier bug. No program starts at insn %d\n", target_insn);
                 return -EFAULT;
         }
 
         caller = state->frame[state->curframe];
         err = btf_check_subprog_call(env, subprog, caller->regs);
         if (err == -EFAULT)
                 return err;
         if (subprog_is_global(env, subprog)) {
                 const char *sub_name = subprog_name(env, subprog);
 
                 /* Only global subprogs cannot be called with a lock held. */
                 if (env->cur_state->active_lock.ptr) {
                         verbose(env, "global function calls are not allowed while holding a lock,\n"
                                      "use static function instead\n");
                         return -EINVAL;
                 }
 
                 /* Only global subprogs cannot be called with preemption disabled. */
                 if (env->cur_state->active_preempt_lock) {
                         verbose(env, "global function calls are not allowed with preemption disabled,\n"
                                      "use static function instead\n");
                         return -EINVAL;
                 }
 
                 if (err) {
                         verbose(env, "Caller passes invalid args into func#%d ('%s')\n",
                                 subprog, sub_name);
                         return err;
                 }
 
                 verbose(env, "Func#%d ('%s') is global and assumed valid.\n",
                         subprog, sub_name);
                 /* mark global subprog for verifying after main prog */
                 subprog_aux(env, subprog)->called = true;
                 clear_caller_saved_regs(env, caller->regs);
 
                 /* All global functions return a 64-bit SCALAR_VALUE */
                 mark_reg_unknown(env, caller->regs, BPF_REG_0);
                 caller->regs[BPF_REG_0].subreg_def = DEF_NOT_SUBREG;
 
                 /* continue with next insn after call */
                 return 0;
         }
 
         /* for regular function entry setup new frame and continue
          * from that frame.
          */
         err = setup_func_entry(env, subprog, *insn_idx, set_callee_state, state);
         if (err)
                 return err;
 
         clear_caller_saved_regs(env, caller->regs);
 
         /* and go analyze first insn of the callee */
         *insn_idx = env->subprog_info[subprog].start - 1;
 
         if (env->log.level & BPF_LOG_LEVEL) {
                 verbose(env, "caller:\n");
                 print_verifier_state(env, caller, true);
                 verbose(env, "callee:\n");
                 print_verifier_state(env, state->frame[state->curframe], true);
         }
 
         return 0;
 }
 
 int map_set_for_each_callback_args(struct bpf_verifier_env *env,
                                    struct bpf_func_state *caller,
                                    struct bpf_func_state *callee)
 {
         /* bpf_for_each_map_elem(struct bpf_map *map, void *callback_fn,
          *      void *callback_ctx, u64 flags);
          * callback_fn(struct bpf_map *map, void *key, void *value,
          *      void *callback_ctx);
          */
         callee->regs[BPF_REG_1] = caller->regs[BPF_REG_1];
 
         callee->regs[BPF_REG_2].type = PTR_TO_MAP_KEY;
         __mark_reg_known_zero(&callee->regs[BPF_REG_2]);
         callee->regs[BPF_REG_2].map_ptr = caller->regs[BPF_REG_1].map_ptr;
 
         callee->regs[BPF_REG_3].type = PTR_TO_MAP_VALUE;
         __mark_reg_known_zero(&callee->regs[BPF_REG_3]);
         callee->regs[BPF_REG_3].map_ptr = caller->regs[BPF_REG_1].map_ptr;
 
         /* pointer to stack or null */
         callee->regs[BPF_REG_4] = caller->regs[BPF_REG_3];
 
         /* unused */
         __mark_reg_not_init(env, &callee->regs[BPF_REG_5]);
         return 0;
 }
 
 static int set_callee_state(struct bpf_verifier_env *env,
                             struct bpf_func_state *caller,
                             struct bpf_func_state *callee, int insn_idx)
 {
         int i;
 
         /* copy r1 - r5 args that callee can access.  The copy includes parent
          * pointers, which connects us up to the liveness chain
          */
         for (i = BPF_REG_1; i <= BPF_REG_5; i++)
                 callee->regs[i] = caller->regs[i];
         return 0;
 }
 
 static int set_map_elem_callback_state(struct bpf_verifier_env *env,
                                        struct bpf_func_state *caller,
                                        struct bpf_func_state *callee,
                                        int insn_idx)
 {
         struct bpf_insn_aux_data *insn_aux = &env->insn_aux_data[insn_idx];
         struct bpf_map *map;
         int err;
 
         /* valid map_ptr and poison value does not matter */
         map = insn_aux->map_ptr_state.map_ptr;
         if (!map->ops->map_set_for_each_callback_args ||
             !map->ops->map_for_each_callback) {
                 verbose(env, "callback function not allowed for map\n");
                 return -ENOTSUPP;
         }
 
         err = map->ops->map_set_for_each_callback_args(env, caller, callee);
         if (err)
                 return err;
 
         callee->in_callback_fn = true;
         callee->callback_ret_range = retval_range(0, 1);
         return 0;
 }
 
 static int set_loop_callback_state(struct bpf_verifier_env *env,
                                    struct bpf_func_state *caller,
                                    struct bpf_func_state *callee,
                                    int insn_idx)
 {
         /* bpf_loop(u32 nr_loops, void *callback_fn, void *callback_ctx,
          *          u64 flags);
          * callback_fn(u32 index, void *callback_ctx);
          */
         callee->regs[BPF_REG_1].type = SCALAR_VALUE;
         callee->regs[BPF_REG_2] = caller->regs[BPF_REG_3];
 
         /* unused */
         __mark_reg_not_init(env, &callee->regs[BPF_REG_3]);
         __mark_reg_not_init(env, &callee->regs[BPF_REG_4]);
         __mark_reg_not_init(env, &callee->regs[BPF_REG_5]);
 
         callee->in_callback_fn = true;
         callee->callback_ret_range = retval_range(0, 1);
         return 0;
 }
 
 static int set_timer_callback_state(struct bpf_verifier_env *env,
                                     struct bpf_func_state *caller,
                                     struct bpf_func_state *callee,
                                     int insn_idx)
 {
         struct bpf_map *map_ptr = caller->regs[BPF_REG_1].map_ptr;
 
         /* bpf_timer_set_callback(struct bpf_timer *timer, void *callback_fn);
          * callback_fn(struct bpf_map *map, void *key, void *value);
          */
         callee->regs[BPF_REG_1].type = CONST_PTR_TO_MAP;
         __mark_reg_known_zero(&callee->regs[BPF_REG_1]);
         callee->regs[BPF_REG_1].map_ptr = map_ptr;
 
         callee->regs[BPF_REG_2].type = PTR_TO_MAP_KEY;
         __mark_reg_known_zero(&callee->regs[BPF_REG_2]);
         callee->regs[BPF_REG_2].map_ptr = map_ptr;
 
         callee->regs[BPF_REG_3].type = PTR_TO_MAP_VALUE;
         __mark_reg_known_zero(&callee->regs[BPF_REG_3]);
         callee->regs[BPF_REG_3].map_ptr = map_ptr;
 
         /* unused */
         __mark_reg_not_init(env, &callee->regs[BPF_REG_4]);
         __mark_reg_not_init(env, &callee->regs[BPF_REG_5]);
         callee->in_async_callback_fn = true;
         callee->callback_ret_range = retval_range(0, 1);
         return 0;
 }
 
 static int set_find_vma_callback_state(struct bpf_verifier_env *env,
                                        struct bpf_func_state *caller,
                                        struct bpf_func_state *callee,
                                        int insn_idx)
 {
         /* bpf_find_vma(struct task_struct *task, u64 addr,
          *               void *callback_fn, void *callback_ctx, u64 flags)
          * (callback_fn)(struct task_struct *task,
          *               struct vm_area_struct *vma, void *callback_ctx);
          */
         callee->regs[BPF_REG_1] = caller->regs[BPF_REG_1];
 
         callee->regs[BPF_REG_2].type = PTR_TO_BTF_ID;
         __mark_reg_known_zero(&callee->regs[BPF_REG_2]);
         callee->regs[BPF_REG_2].btf =  btf_vmlinux;
         callee->regs[BPF_REG_2].btf_id = btf_tracing_ids[BTF_TRACING_TYPE_VMA];
 
         /* pointer to stack or null */
         callee->regs[BPF_REG_3] = caller->regs[BPF_REG_4];
 
         /* unused */
         __mark_reg_not_init(env, &callee->regs[BPF_REG_4]);
         __mark_reg_not_init(env, &callee->regs[BPF_REG_5]);
         callee->in_callback_fn = true;
         callee->callback_ret_range = retval_range(0, 1);
         return 0;
 }
 
 static int set_user_ringbuf_callback_state(struct bpf_verifier_env *env,
                                            struct bpf_func_state *caller,
                                            struct bpf_func_state *callee,
                                            int insn_idx)
 {
         /* bpf_user_ringbuf_drain(struct bpf_map *map, void *callback_fn, void
          *                        callback_ctx, u64 flags);
          * callback_fn(const struct bpf_dynptr_t* dynptr, void *callback_ctx);
          */
         __mark_reg_not_init(env, &callee->regs[BPF_REG_0]);
         mark_dynptr_cb_reg(env, &callee->regs[BPF_REG_1], BPF_DYNPTR_TYPE_LOCAL);
         callee->regs[BPF_REG_2] = caller->regs[BPF_REG_3];
 
         /* unused */
         __mark_reg_not_init(env, &callee->regs[BPF_REG_3]);
         __mark_reg_not_init(env, &callee->regs[BPF_REG_4]);
         __mark_reg_not_init(env, &callee->regs[BPF_REG_5]);
 
         callee->in_callback_fn = true;
         callee->callback_ret_range = retval_range(0, 1);
         return 0;
 }
 
 static int set_rbtree_add_callback_state(struct bpf_verifier_env *env,
                                          struct bpf_func_state *caller,
                                          struct bpf_func_state *callee,
                                          int insn_idx)
 {
         /* void bpf_rbtree_add_impl(struct bpf_rb_root *root, struct bpf_rb_node *node,
          *                     bool (less)(struct bpf_rb_node *a, const struct bpf_rb_node *b));
          *
          * 'struct bpf_rb_node *node' arg to bpf_rbtree_add_impl is the same PTR_TO_BTF_ID w/ offset
          * that 'less' callback args will be receiving. However, 'node' arg was release_reference'd
          * by this point, so look at 'root'
          */
         struct btf_field *field;
 
         field = reg_find_field_offset(&caller->regs[BPF_REG_1], caller->regs[BPF_REG_1].off,
                                       BPF_RB_ROOT);
         if (!field || !field->graph_root.value_btf_id)
                 return -EFAULT;
 
         mark_reg_graph_node(callee->regs, BPF_REG_1, &field->graph_root);
         ref_set_non_owning(env, &callee->regs[BPF_REG_1]);
         mark_reg_graph_node(callee->regs, BPF_REG_2, &field->graph_root);
         ref_set_non_owning(env, &callee->regs[BPF_REG_2]);
 
         __mark_reg_not_init(env, &callee->regs[BPF_REG_3]);
         __mark_reg_not_init(env, &callee->regs[BPF_REG_4]);
         __mark_reg_not_init(env, &callee->regs[BPF_REG_5]);
         callee->in_callback_fn = true;
         callee->callback_ret_range = retval_range(0, 1);
         return 0;
 }
 
 static bool is_rbtree_lock_required_kfunc(u32 btf_id);
 
 /* Are we currently verifying the callback for a rbtree helper that must
  * be called with lock held? If so, no need to complain about unreleased
  * lock
  */
 static bool in_rbtree_lock_required_cb(struct bpf_verifier_env *env)
 {
         struct bpf_verifier_state *state = env->cur_state;
         struct bpf_insn *insn = env->prog->insnsi;
         struct bpf_func_state *callee;
         int kfunc_btf_id;
 
         if (!state->curframe)
                 return false;
 
         callee = state->frame[state->curframe];
 
         if (!callee->in_callback_fn)
                 return false;
 
         kfunc_btf_id = insn[callee->callsite].imm;
         return is_rbtree_lock_required_kfunc(kfunc_btf_id);
 }
 
 static bool retval_range_within(struct bpf_retval_range range, const struct bpf_reg_state *reg,
                                 bool return_32bit)
 {
         if (return_32bit)
                 return range.minval <= reg->s32_min_value && reg->s32_max_value <= range.maxval;
         else
                 return range.minval <= reg->smin_value && reg->smax_value <= range.maxval;
 }
 
 static int prepare_func_exit(struct bpf_verifier_env *env, int *insn_idx)
 {
         struct bpf_verifier_state *state = env->cur_state, *prev_st;
         struct bpf_func_state *caller, *callee;
         struct bpf_reg_state *r0;
         bool in_callback_fn;
         int err;
 
         callee = state->frame[state->curframe];
         r0 = &callee->regs[BPF_REG_0];
         if (r0->type == PTR_TO_STACK) {
                 /* technically it's ok to return caller's stack pointer
                  * (or caller's caller's pointer) back to the caller,
                  * since these pointers are valid. Only current stack
                  * pointer will be invalid as soon as function exits,
                  * but let's be conservative
                  */
                 verbose(env, "cannot return stack pointer to the caller\n");
                 return -EINVAL;
         }
 
         caller = state->frame[state->curframe - 1];
         if (callee->in_callback_fn) {
                 if (r0->type != SCALAR_VALUE) {
                         verbose(env, "R0 not a scalar value\n");
                         return -EACCES;
                 }
 
                 /* we are going to rely on register's precise value */
                 err = mark_reg_read(env, r0, r0->parent, REG_LIVE_READ64);
                 err = err ?: mark_chain_precision(env, BPF_REG_0);
                 if (err)
                         return err;
 
                 /* enforce R0 return value range, and bpf_callback_t returns 64bit */
                 if (!retval_range_within(callee->callback_ret_range, r0, false)) {
                         verbose_invalid_scalar(env, r0, callee->callback_ret_range,
                                                "At callback return", "R0");
                         return -EINVAL;
                 }
                 if (!calls_callback(env, callee->callsite)) {
                         verbose(env, "BUG: in callback at %d, callsite %d !calls_callback\n",
                                 *insn_idx, callee->callsite);
                         return -EFAULT;
                 }
         } else {
                 /* return to the caller whatever r0 had in the callee */
                 caller->regs[BPF_REG_0] = *r0;
         }
 
         /* callback_fn frame should have released its own additions to parent's
          * reference state at this point, or check_reference_leak would
          * complain, hence it must be the same as the caller. There is no need
          * to copy it back.
          */
         if (!callee->in_callback_fn) {
                 /* Transfer references to the caller */
                 err = copy_reference_state(caller, callee);
                 if (err)
                         return err;
         }
 
         /* for callbacks like bpf_loop or bpf_for_each_map_elem go back to callsite,
          * there function call logic would reschedule callback visit. If iteration
          * converges is_state_visited() would prune that visit eventually.
          */
         in_callback_fn = callee->in_callback_fn;
         if (in_callback_fn)
                 *insn_idx = callee->callsite;
         else
                 *insn_idx = callee->callsite + 1;
 
         if (env->log.level & BPF_LOG_LEVEL) {
                 verbose(env, "returning from callee:\n");
                 print_verifier_state(env, callee, true);
                 verbose(env, "to caller at %d:\n", *insn_idx);
                 print_verifier_state(env, caller, true);
         }
         /* clear everything in the callee. In case of exceptional exits using
          * bpf_throw, this will be done by copy_verifier_state for extra frames. */
         free_func_state(callee);
         state->frame[state->curframe--] = NULL;
 
         /* for callbacks widen imprecise scalars to make programs like below verify:
          *
          *   struct ctx { int i; }
          *   void cb(int idx, struct ctx *ctx) { ctx->i++; ... }
          *   ...
          *   struct ctx = { .i = 0; }
          *   bpf_loop(100, cb, &ctx, 0);
          *
          * This is similar to what is done in process_iter_next_call() for open
          * coded iterators.
          */
         prev_st = in_callback_fn ? find_prev_entry(env, state, *insn_idx) : NULL;
         if (prev_st) {
                 err = widen_imprecise_scalars(env, prev_st, state);
                 if (err)
                         return err;
         }
         return 0;
 }
 
 static int do_refine_retval_range(struct bpf_verifier_env *env,
                                   struct bpf_reg_state *regs, int ret_type,
                                   int func_id,
                                   struct bpf_call_arg_meta *meta)
 {
         struct bpf_reg_state *ret_reg = &regs[BPF_REG_0];
 
         if (ret_type != RET_INTEGER)
                 return 0;
 
         switch (func_id) {
         case BPF_FUNC_get_stack:
         case BPF_FUNC_get_task_stack:
         case BPF_FUNC_probe_read_str:
         case BPF_FUNC_probe_read_kernel_str:
         case BPF_FUNC_probe_read_user_str:
                 ret_reg->smax_value = meta->msize_max_value;
                 ret_reg->s32_max_value = meta->msize_max_value;
                 ret_reg->smin_value = -MAX_ERRNO;
                 ret_reg->s32_min_value = -MAX_ERRNO;
                 reg_bounds_sync(ret_reg);
                 break;
         case BPF_FUNC_get_smp_processor_id:
                 ret_reg->umax_value = nr_cpu_ids - 1;
                 ret_reg->u32_max_value = nr_cpu_ids - 1;
                 ret_reg->smax_value = nr_cpu_ids - 1;
                 ret_reg->s32_max_value = nr_cpu_ids - 1;
                 ret_reg->umin_value = 0;
                 ret_reg->u32_min_value = 0;
                 ret_reg->smin_value = 0;
                 ret_reg->s32_min_value = 0;
                 reg_bounds_sync(ret_reg);
                 break;
         }
 
         return reg_bounds_sanity_check(env, ret_reg, "retval");
 }
 
 static int
 record_func_map(struct bpf_verifier_env *env, struct bpf_call_arg_meta *meta,
                 int func_id, int insn_idx)
 {
         struct bpf_insn_aux_data *aux = &env->insn_aux_data[insn_idx];
         struct bpf_map *map = meta->map_ptr;
 
         if (func_id != BPF_FUNC_tail_call &&
             func_id != BPF_FUNC_map_lookup_elem &&
             func_id != BPF_FUNC_map_update_elem &&
             func_id != BPF_FUNC_map_delete_elem &&
             func_id != BPF_FUNC_map_push_elem &&
             func_id != BPF_FUNC_map_pop_elem &&
             func_id != BPF_FUNC_map_peek_elem &&
             func_id != BPF_FUNC_for_each_map_elem &&
             func_id != BPF_FUNC_redirect_map &&
             func_id != BPF_FUNC_map_lookup_percpu_elem)
                 return 0;
 
         if (map == NULL) {
                 verbose(env, "kernel subsystem misconfigured verifier\n");
                 return -EINVAL;
         }
 
         /* In case of read-only, some additional restrictions
          * need to be applied in order to prevent altering the
          * state of the map from program side.
          */
         if ((map->map_flags & BPF_F_RDONLY_PROG) &&
             (func_id == BPF_FUNC_map_delete_elem ||
              func_id == BPF_FUNC_map_update_elem ||
              func_id == BPF_FUNC_map_push_elem ||
              func_id == BPF_FUNC_map_pop_elem)) {
                 verbose(env, "write into map forbidden\n");
                 return -EACCES;
         }
 
         if (!aux->map_ptr_state.map_ptr)
                 bpf_map_ptr_store(aux, meta->map_ptr,
                                   !meta->map_ptr->bypass_spec_v1, false);
         else if (aux->map_ptr_state.map_ptr != meta->map_ptr)
                 bpf_map_ptr_store(aux, meta->map_ptr,
                                   !meta->map_ptr->bypass_spec_v1, true);
         return 0;
 }
 
 static int
 record_func_key(struct bpf_verifier_env *env, struct bpf_call_arg_meta *meta,
                 int func_id, int insn_idx)
 {
         struct bpf_insn_aux_data *aux = &env->insn_aux_data[insn_idx];
         struct bpf_reg_state *regs = cur_regs(env), *reg;
         struct bpf_map *map = meta->map_ptr;
         u64 val, max;
         int err;
 
         if (func_id != BPF_FUNC_tail_call)
                 return 0;
         if (!map || map->map_type != BPF_MAP_TYPE_PROG_ARRAY) {
                 verbose(env, "kernel subsystem misconfigured verifier\n");
                 return -EINVAL;
         }
 
         reg = &regs[BPF_REG_3];
         val = reg->var_off.value;
         max = map->max_entries;
 
         if (!(is_reg_const(reg, false) && val < max)) {
                 bpf_map_key_store(aux, BPF_MAP_KEY_POISON);
                 return 0;
         }
 
         err = mark_chain_precision(env, BPF_REG_3);
         if (err)
                 return err;
         if (bpf_map_key_unseen(aux))
                 bpf_map_key_store(aux, val);
         else if (!bpf_map_key_poisoned(aux) &&
                   bpf_map_key_immediate(aux) != val)
                 bpf_map_key_store(aux, BPF_MAP_KEY_POISON);
         return 0;
 }
 
 static int check_reference_leak(struct bpf_verifier_env *env, bool exception_exit)
 {
         struct bpf_func_state *state = cur_func(env);
         bool refs_lingering = false;
         int i;
 
         if (!exception_exit && state->frameno && !state->in_callback_fn)
                 return 0;
 
         for (i = 0; i < state->acquired_refs; i++) {
                 if (!exception_exit && state->in_callback_fn && state->refs[i].callback_ref != state->frameno)
                         continue;
                 verbose(env, "Unreleased reference id=%d alloc_insn=%d\n",
                         state->refs[i].id, state->refs[i].insn_idx);
                 refs_lingering = true;
         }
         return refs_lingering ? -EINVAL : 0;
 }
 
 static int check_bpf_snprintf_call(struct bpf_verifier_env *env,
                                    struct bpf_reg_state *regs)
 {
         struct bpf_reg_state *fmt_reg = &regs[BPF_REG_3];
         struct bpf_reg_state *data_len_reg = &regs[BPF_REG_5];
         struct bpf_map *fmt_map = fmt_reg->map_ptr;
         struct bpf_bprintf_data data = {};
         int err, fmt_map_off, num_args;
         u64 fmt_addr;
         char *fmt;
 
         /* data must be an array of u64 */
         if (data_len_reg->var_off.value % 8)
                 return -EINVAL;
         num_args = data_len_reg->var_off.value / 8;
 
         /* fmt being ARG_PTR_TO_CONST_STR guarantees that var_off is const
          * and map_direct_value_addr is set.
          */
         fmt_map_off = fmt_reg->off + fmt_reg->var_off.value;
         err = fmt_map->ops->map_direct_value_addr(fmt_map, &fmt_addr,
                                                   fmt_map_off);
         if (err) {
                 verbose(env, "verifier bug\n");
                 return -EFAULT;
         }
         fmt = (char *)(long)fmt_addr + fmt_map_off;
 
         /* We are also guaranteed that fmt+fmt_map_off is NULL terminated, we
          * can focus on validating the format specifiers.
          */
         err = bpf_bprintf_prepare(fmt, UINT_MAX, NULL, num_args, &data);
         if (err < 0)
                 verbose(env, "Invalid format string\n");
 
         return err;
 }
 
 static int check_get_func_ip(struct bpf_verifier_env *env)
 {
         enum bpf_prog_type type = resolve_prog_type(env->prog);
         int func_id = BPF_FUNC_get_func_ip;
 
         if (type == BPF_PROG_TYPE_TRACING) {
                 if (!bpf_prog_has_trampoline(env->prog)) {
                         verbose(env, "func %s#%d supported only for fentry/fexit/fmod_ret programs\n",
                                 func_id_name(func_id), func_id);
                         return -ENOTSUPP;
                 }
                 return 0;
         } else if (type == BPF_PROG_TYPE_KPROBE) {
                 return 0;
         }
 
         verbose(env, "func %s#%d not supported for program type %d\n",
                 func_id_name(func_id), func_id, type);
         return -ENOTSUPP;
 }
 
 static struct bpf_insn_aux_data *cur_aux(struct bpf_verifier_env *env)
 {
         return &env->insn_aux_data[env->insn_idx];
 }
 
 static bool loop_flag_is_zero(struct bpf_verifier_env *env)
 {
         struct bpf_reg_state *regs = cur_regs(env);
         struct bpf_reg_state *reg = &regs[BPF_REG_4];
         bool reg_is_null = register_is_null(reg);
 
         if (reg_is_null)
                 mark_chain_precision(env, BPF_REG_4);
 
         return reg_is_null;
 }
 
 static void update_loop_inline_state(struct bpf_verifier_env *env, u32 subprogno)
 {
         struct bpf_loop_inline_state *state = &cur_aux(env)->loop_inline_state;
 
         if (!state->initialized) {
                 state->initialized = 1;
                 state->fit_for_inline = loop_flag_is_zero(env);
                 state->callback_subprogno = subprogno;
                 return;
         }
 
         if (!state->fit_for_inline)
                 return;
 
         state->fit_for_inline = (loop_flag_is_zero(env) &&
                                  state->callback_subprogno == subprogno);
 }
 
 static int check_helper_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
                              int *insn_idx_p)
 {
         enum bpf_prog_type prog_type = resolve_prog_type(env->prog);
         bool returns_cpu_specific_alloc_ptr = false;
         const struct bpf_func_proto *fn = NULL;
         enum bpf_return_type ret_type;
         enum bpf_type_flag ret_flag;
         struct bpf_reg_state *regs;
         struct bpf_call_arg_meta meta;
         int insn_idx = *insn_idx_p;
         bool changes_data;
         int i, err, func_id;
 
         /* find function prototype */
         func_id = insn->imm;
         if (func_id < 0 || func_id >= __BPF_FUNC_MAX_ID) {
                 verbose(env, "invalid func %s#%d\n", func_id_name(func_id),
                         func_id);
                 return -EINVAL;
         }
 
         if (env->ops->get_func_proto)
                 fn = env->ops->get_func_proto(func_id, env->prog);
         if (!fn) {
                 verbose(env, "program of this type cannot use helper %s#%d\n",
                         func_id_name(func_id), func_id);
                 return -EINVAL;
         }
 
         /* eBPF programs must be GPL compatible to use GPL-ed functions */
         if (!env->prog->gpl_compatible && fn->gpl_only) {
                 verbose(env, "cannot call GPL-restricted function from non-GPL compatible program\n");
                 return -EINVAL;
         }
 
         if (fn->allowed && !fn->allowed(env->prog)) {
                 verbose(env, "helper call is not allowed in probe\n");
                 return -EINVAL;
         }
 
         if (!in_sleepable(env) && fn->might_sleep) {
                 verbose(env, "helper call might sleep in a non-sleepable prog\n");
                 return -EINVAL;
         }
 
         /* With LD_ABS/IND some JITs save/restore skb from r1. */
         changes_data = bpf_helper_changes_pkt_data(fn->func);
         if (changes_data && fn->arg1_type != ARG_PTR_TO_CTX) {
                 verbose(env, "kernel subsystem misconfigured func %s#%d: r1 != ctx\n",
                         func_id_name(func_id), func_id);
                 return -EINVAL;
         }
 
         memset(&meta, 0, sizeof(meta));
         meta.pkt_access = fn->pkt_access;
 
         err = check_func_proto(fn, func_id);
         if (err) {
                 verbose(env, "kernel subsystem misconfigured func %s#%d\n",
                         func_id_name(func_id), func_id);
                 return err;
         }
 
         if (env->cur_state->active_rcu_lock) {
                 if (fn->might_sleep) {
                         verbose(env, "sleepable helper %s#%d in rcu_read_lock region\n",
                                 func_id_name(func_id), func_id);
                         return -EINVAL;
                 }
 
                 if (in_sleepable(env) && is_storage_get_function(func_id))
                         env->insn_aux_data[insn_idx].storage_get_func_atomic = true;
         }
 
         if (env->cur_state->active_preempt_lock) {
                 if (fn->might_sleep) {
                         verbose(env, "sleepable helper %s#%d in non-preemptible region\n",
                                 func_id_name(func_id), func_id);
                         return -EINVAL;
                 }
 
                 if (in_sleepable(env) && is_storage_get_function(func_id))
                         env->insn_aux_data[insn_idx].storage_get_func_atomic = true;
         }
 
         meta.func_id = func_id;
         /* check args */
         for (i = 0; i < MAX_BPF_FUNC_REG_ARGS; i++) {
                 err = check_func_arg(env, i, &meta, fn, insn_idx);
                 if (err)
                         return err;
         }
 
         err = record_func_map(env, &meta, func_id, insn_idx);
         if (err)
                 return err;
 
         err = record_func_key(env, &meta, func_id, insn_idx);
         if (err)
                 return err;
 
         /* Mark slots with STACK_MISC in case of raw mode, stack offset
          * is inferred from register state.
          */
         for (i = 0; i < meta.access_size; i++) {
                 err = check_mem_access(env, insn_idx, meta.regno, i, BPF_B,
                                        BPF_WRITE, -1, false, false);
                 if (err)
                         return err;
         }
 
         regs = cur_regs(env);
 
         if (meta.release_regno) {
                 err = -EINVAL;
                 /* This can only be set for PTR_TO_STACK, as CONST_PTR_TO_DYNPTR cannot
                  * be released by any dynptr helper. Hence, unmark_stack_slots_dynptr
                  * is safe to do directly.
                  */
                 if (arg_type_is_dynptr(fn->arg_type[meta.release_regno - BPF_REG_1])) {
                         if (regs[meta.release_regno].type == CONST_PTR_TO_DYNPTR) {
                                 verbose(env, "verifier internal error: CONST_PTR_TO_DYNPTR cannot be released\n");
                                 return -EFAULT;
                         }
                         err = unmark_stack_slots_dynptr(env, &regs[meta.release_regno]);
                 } else if (func_id == BPF_FUNC_kptr_xchg && meta.ref_obj_id) {
                         u32 ref_obj_id = meta.ref_obj_id;
                         bool in_rcu = in_rcu_cs(env);
                         struct bpf_func_state *state;
                         struct bpf_reg_state *reg;
 
                         err = release_reference_state(cur_func(env), ref_obj_id);
                         if (!err) {
                                 bpf_for_each_reg_in_vstate(env->cur_state, state, reg, ({
                                         if (reg->ref_obj_id == ref_obj_id) {
                                                 if (in_rcu && (reg->type & MEM_ALLOC) && (reg->type & MEM_PERCPU)) {
                                                         reg->ref_obj_id = 0;
                                                         reg->type &= ~MEM_ALLOC;
                                                         reg->type |= MEM_RCU;
                                                 } else {
                                                         mark_reg_invalid(env, reg);
                                                 }
                                         }
                                 }));
                         }
                 } else if (meta.ref_obj_id) {
                         err = release_reference(env, meta.ref_obj_id);
                 } else if (register_is_null(&regs[meta.release_regno])) {
                         /* meta.ref_obj_id can only be 0 if register that is meant to be
                          * released is NULL, which must be > R0.
                          */
                         err = 0;
                 }
                 if (err) {
                         verbose(env, "func %s#%d reference has not been acquired before\n",
                                 func_id_name(func_id), func_id);
                         return err;
                 }
         }
 
         switch (func_id) {
         case BPF_FUNC_tail_call:
                 err = check_reference_leak(env, false);
                 if (err) {
                         verbose(env, "tail_call would lead to reference leak\n");
                         return err;
                 }
                 break;
         case BPF_FUNC_get_local_storage:
                 /* check that flags argument in get_local_storage(map, flags) is 0,
                  * this is required because get_local_storage() can't return an error.
                  */
                 if (!register_is_null(&regs[BPF_REG_2])) {
                         verbose(env, "get_local_storage() doesn't support non-zero flags\n");
                         return -EINVAL;
                 }
                 break;
         case BPF_FUNC_for_each_map_elem:
                 err = push_callback_call(env, insn, insn_idx, meta.subprogno,
                                          set_map_elem_callback_state);
                 break;
         case BPF_FUNC_timer_set_callback:
                 err = push_callback_call(env, insn, insn_idx, meta.subprogno,
                                          set_timer_callback_state);
                 break;
         case BPF_FUNC_find_vma:
                 err = push_callback_call(env, insn, insn_idx, meta.subprogno,
                                          set_find_vma_callback_state);
                 break;
         case BPF_FUNC_snprintf:
                 err = check_bpf_snprintf_call(env, regs);
                 break;
         case BPF_FUNC_loop:
                 update_loop_inline_state(env, meta.subprogno);
                 /* Verifier relies on R1 value to determine if bpf_loop() iteration
                  * is finished, thus mark it precise.
                  */
                 err = mark_chain_precision(env, BPF_REG_1);
                 if (err)
                         return err;
                 if (cur_func(env)->callback_depth < regs[BPF_REG_1].umax_value) {
                         err = push_callback_call(env, insn, insn_idx, meta.subprogno,
                                                  set_loop_callback_state);
                 } else {
                         cur_func(env)->callback_depth = 0;
                         if (env->log.level & BPF_LOG_LEVEL2)
                                 verbose(env, "frame%d bpf_loop iteration limit reached\n",
                                         env->cur_state->curframe);
                 }
                 break;
         case BPF_FUNC_dynptr_from_mem:
                 if (regs[BPF_REG_1].type != PTR_TO_MAP_VALUE) {
                         verbose(env, "Unsupported reg type %s for bpf_dynptr_from_mem data\n",
                                 reg_type_str(env, regs[BPF_REG_1].type));
                         return -EACCES;
                 }
                 break;
         case BPF_FUNC_set_retval:
                 if (prog_type == BPF_PROG_TYPE_LSM &&
                     env->prog->expected_attach_type == BPF_LSM_CGROUP) {
                         if (!env->prog->aux->attach_func_proto->type) {
                                 /* Make sure programs that attach to void
                                  * hooks don't try to modify return value.
                                  */
                                 verbose(env, "BPF_LSM_CGROUP that attach to void LSM hooks can't modify return value!\n");
                                 return -EINVAL;
                         }
                 }
                 break;
         case BPF_FUNC_dynptr_data:
         {
                 struct bpf_reg_state *reg;
                 int id, ref_obj_id;
 
                 reg = get_dynptr_arg_reg(env, fn, regs);
                 if (!reg)
                         return -EFAULT;
 
 
                 if (meta.dynptr_id) {
                         verbose(env, "verifier internal error: meta.dynptr_id already set\n");
                         return -EFAULT;
                 }
                 if (meta.ref_obj_id) {
                         verbose(env, "verifier internal error: meta.ref_obj_id already set\n");
                         return -EFAULT;
                 }
 
                 id = dynptr_id(env, reg);
                 if (id < 0) {
                         verbose(env, "verifier internal error: failed to obtain dynptr id\n");
                         return id;
                 }
 
                 ref_obj_id = dynptr_ref_obj_id(env, reg);
                 if (ref_obj_id < 0) {
                         verbose(env, "verifier internal error: failed to obtain dynptr ref_obj_id\n");
                         return ref_obj_id;
                 }
 
                 meta.dynptr_id = id;
                 meta.ref_obj_id = ref_obj_id;
 
                 break;
         }
         case BPF_FUNC_dynptr_write:
         {
                 enum bpf_dynptr_type dynptr_type;
                 struct bpf_reg_state *reg;
 
                 reg = get_dynptr_arg_reg(env, fn, regs);
                 if (!reg)
                         return -EFAULT;
 
                 dynptr_type = dynptr_get_type(env, reg);
                 if (dynptr_type == BPF_DYNPTR_TYPE_INVALID)
                         return -EFAULT;
 
                 if (dynptr_type == BPF_DYNPTR_TYPE_SKB)
                         /* this will trigger clear_all_pkt_pointers(), which will
                          * invalidate all dynptr slices associated with the skb
                          */
                         changes_data = true;
 
                 break;
         }
         case BPF_FUNC_per_cpu_ptr:
         case BPF_FUNC_this_cpu_ptr:
         {
                 struct bpf_reg_state *reg = &regs[BPF_REG_1];
                 const struct btf_type *type;
 
                 if (reg->type & MEM_RCU) {
                         type = btf_type_by_id(reg->btf, reg->btf_id);
                         if (!type || !btf_type_is_struct(type)) {
                                 verbose(env, "Helper has invalid btf/btf_id in R1\n");
                                 return -EFAULT;
                         }
                         returns_cpu_specific_alloc_ptr = true;
                         env->insn_aux_data[insn_idx].call_with_percpu_alloc_ptr = true;
                 }
                 break;
         }
         case BPF_FUNC_user_ringbuf_drain:
                 err = push_callback_call(env, insn, insn_idx, meta.subprogno,
                                          set_user_ringbuf_callback_state);
                 break;
         }
 
         if (err)
                 return err;
 
         /* reset caller saved regs */
         for (i = 0; i < CALLER_SAVED_REGS; i++) {
                 mark_reg_not_init(env, regs, caller_saved[i]);
                 check_reg_arg(env, caller_saved[i], DST_OP_NO_MARK);
         }
 
         /* helper call returns 64-bit value. */
         regs[BPF_REG_0].subreg_def = DEF_NOT_SUBREG;
 
         /* update return register (already marked as written above) */
         ret_type = fn->ret_type;
         ret_flag = type_flag(ret_type);
 
         switch (base_type(ret_type)) {
         case RET_INTEGER:
                 /* sets type to SCALAR_VALUE */
                 mark_reg_unknown(env, regs, BPF_REG_0);
                 break;
         case RET_VOID:
                 regs[BPF_REG_0].type = NOT_INIT;
                 break;
         case RET_PTR_TO_MAP_VALUE:
                 /* There is no offset yet applied, variable or fixed */
                 mark_reg_known_zero(env, regs, BPF_REG_0);
                 /* remember map_ptr, so that check_map_access()
                  * can check 'value_size' boundary of memory access
                  * to map element returned from bpf_map_lookup_elem()
                  */
                 if (meta.map_ptr == NULL) {
                         verbose(env,
                                 "kernel subsystem misconfigured verifier\n");
                         return -EINVAL;
                 }
                 regs[BPF_REG_0].map_ptr = meta.map_ptr;
                 regs[BPF_REG_0].map_uid = meta.map_uid;
                 regs[BPF_REG_0].type = PTR_TO_MAP_VALUE | ret_flag;
                 if (!type_may_be_null(ret_type) &&
                     btf_record_has_field(meta.map_ptr->record, BPF_SPIN_LOCK)) {
                         regs[BPF_REG_0].id = ++env->id_gen;
                 }
                 break;
         case RET_PTR_TO_SOCKET:
                 mark_reg_known_zero(env, regs, BPF_REG_0);
                 regs[BPF_REG_0].type = PTR_TO_SOCKET | ret_flag;
                 break;
         case RET_PTR_TO_SOCK_COMMON:
                 mark_reg_known_zero(env, regs, BPF_REG_0);
                 regs[BPF_REG_0].type = PTR_TO_SOCK_COMMON | ret_flag;
                 break;
         case RET_PTR_TO_TCP_SOCK:
                 mark_reg_known_zero(env, regs, BPF_REG_0);
                 regs[BPF_REG_0].type = PTR_TO_TCP_SOCK | ret_flag;
                 break;
         case RET_PTR_TO_MEM:
                 mark_reg_known_zero(env, regs, BPF_REG_0);
                 regs[BPF_REG_0].type = PTR_TO_MEM | ret_flag;
                 regs[BPF_REG_0].mem_size = meta.mem_size;
                 break;
         case RET_PTR_TO_MEM_OR_BTF_ID:
         {
                 const struct btf_type *t;
 
                 mark_reg_known_zero(env, regs, BPF_REG_0);
                 t = btf_type_skip_modifiers(meta.ret_btf, meta.ret_btf_id, NULL);
                 if (!btf_type_is_struct(t)) {
                         u32 tsize;
                         const struct btf_type *ret;
                         const char *tname;
 
                         /* resolve the type size of ksym. */
                         ret = btf_resolve_size(meta.ret_btf, t, &tsize);
                         if (IS_ERR(ret)) {
                                 tname = btf_name_by_offset(meta.ret_btf, t->name_off);
                                 verbose(env, "unable to resolve the size of type '%s': %ld\n",
                                         tname, PTR_ERR(ret));
                                 return -EINVAL;
                         }
                         regs[BPF_REG_0].type = PTR_TO_MEM | ret_flag;
                         regs[BPF_REG_0].mem_size = tsize;
                 } else {
                         if (returns_cpu_specific_alloc_ptr) {
                                 regs[BPF_REG_0].type = PTR_TO_BTF_ID | MEM_ALLOC | MEM_RCU;
                         } else {
                                 /* MEM_RDONLY may be carried from ret_flag, but it
                                  * doesn't apply on PTR_TO_BTF_ID. Fold it, otherwise
                                  * it will confuse the check of PTR_TO_BTF_ID in
                                  * check_mem_access().
                                  */
                                 ret_flag &= ~MEM_RDONLY;
                                 regs[BPF_REG_0].type = PTR_TO_BTF_ID | ret_flag;
                         }
 
                         regs[BPF_REG_0].btf = meta.ret_btf;
                         regs[BPF_REG_0].btf_id = meta.ret_btf_id;
                 }
                 break;
         }
         case RET_PTR_TO_BTF_ID:
         {
                 struct btf *ret_btf;
                 int ret_btf_id;
 
                 mark_reg_known_zero(env, regs, BPF_REG_0);
                 regs[BPF_REG_0].type = PTR_TO_BTF_ID | ret_flag;
                 if (func_id == BPF_FUNC_kptr_xchg) {
                         ret_btf = meta.kptr_field->kptr.btf;
                         ret_btf_id = meta.kptr_field->kptr.btf_id;
                         if (!btf_is_kernel(ret_btf)) {
                                 regs[BPF_REG_0].type |= MEM_ALLOC;
                                 if (meta.kptr_field->type == BPF_KPTR_PERCPU)
                                         regs[BPF_REG_0].type |= MEM_PERCPU;
                         }
                 } else {
                         if (fn->ret_btf_id == BPF_PTR_POISON) {
                                 verbose(env, "verifier internal error:");
                                 verbose(env, "func %s has non-overwritten BPF_PTR_POISON return type\n",
                                         func_id_name(func_id));
                                 return -EINVAL;
                         }
                         ret_btf = btf_vmlinux;
                         ret_btf_id = *fn->ret_btf_id;
                 }
                 if (ret_btf_id == 0) {
                         verbose(env, "invalid return type %u of func %s#%d\n",
                                 base_type(ret_type), func_id_name(func_id),
                                 func_id);
                         return -EINVAL;
                 }
                 regs[BPF_REG_0].btf = ret_btf;
                 regs[BPF_REG_0].btf_id = ret_btf_id;
                 break;
         }
         default:
                 verbose(env, "unknown return type %u of func %s#%d\n",
                         base_type(ret_type), func_id_name(func_id), func_id);
                 return -EINVAL;
         }
 
         if (type_may_be_null(regs[BPF_REG_0].type))
                 regs[BPF_REG_0].id = ++env->id_gen;
 
         if (helper_multiple_ref_obj_use(func_id, meta.map_ptr)) {
                 verbose(env, "verifier internal error: func %s#%d sets ref_obj_id more than once\n",
                         func_id_name(func_id), func_id);
                 return -EFAULT;
         }
 
         if (is_dynptr_ref_function(func_id))
                 regs[BPF_REG_0].dynptr_id = meta.dynptr_id;
 
         if (is_ptr_cast_function(func_id) || is_dynptr_ref_function(func_id)) {
                 /* For release_reference() */
                 regs[BPF_REG_0].ref_obj_id = meta.ref_obj_id;
         } else if (is_acquire_function(func_id, meta.map_ptr)) {
                 int id = acquire_reference_state(env, insn_idx);
 
                 if (id < 0)
                         return id;
                 /* For mark_ptr_or_null_reg() */
                 regs[BPF_REG_0].id = id;
                 /* For release_reference() */
                 regs[BPF_REG_0].ref_obj_id = id;
         }
 
         err = do_refine_retval_range(env, regs, fn->ret_type, func_id, &meta);
         if (err)
                 return err;
 
         err = check_map_func_compatibility(env, meta.map_ptr, func_id);
         if (err)
                 return err;
 
         if ((func_id == BPF_FUNC_get_stack ||
              func_id == BPF_FUNC_get_task_stack) &&
             !env->prog->has_callchain_buf) {
                 const char *err_str;
 
 #ifdef CONFIG_PERF_EVENTS
                 err = get_callchain_buffers(sysctl_perf_event_max_stack);
                 err_str = "cannot get callchain buffer for func %s#%d\n";
 #else
                 err = -ENOTSUPP;
                 err_str = "func %s#%d not supported without CONFIG_PERF_EVENTS\n";
 #endif
                 if (err) {
                         verbose(env, err_str, func_id_name(func_id), func_id);
                         return err;
                 }
 
                 env->prog->has_callchain_buf = true;
         }
 
         if (func_id == BPF_FUNC_get_stackid || func_id == BPF_FUNC_get_stack)
                 env->prog->call_get_stack = true;
 
         if (func_id == BPF_FUNC_get_func_ip) {
                 if (check_get_func_ip(env))
                         return -ENOTSUPP;
                 env->prog->call_get_func_ip = true;
         }
 
         if (changes_data)
                 clear_all_pkt_pointers(env);
         return 0;
 }
 
 /* mark_btf_func_reg_size() is used when the reg size is determined by
  * the BTF func_proto's return value size and argument.
  */
 static void mark_btf_func_reg_size(struct bpf_verifier_env *env, u32 regno,
                                    size_t reg_size)
 {
         struct bpf_reg_state *reg = &cur_regs(env)[regno];
 
         if (regno == BPF_REG_0) {
                 /* Function return value */
                 reg->live |= REG_LIVE_WRITTEN;
                 reg->subreg_def = reg_size == sizeof(u64) ?
                         DEF_NOT_SUBREG : env->insn_idx + 1;
         } else {
                 /* Function argument */
                 if (reg_size == sizeof(u64)) {
                         mark_insn_zext(env, reg);
                         mark_reg_read(env, reg, reg->parent, REG_LIVE_READ64);
                 } else {
                         mark_reg_read(env, reg, reg->parent, REG_LIVE_READ32);
                 }
         }
 }
 
 static bool is_kfunc_acquire(struct bpf_kfunc_call_arg_meta *meta)
 {
         return meta->kfunc_flags & KF_ACQUIRE;
 }
 
 static bool is_kfunc_release(struct bpf_kfunc_call_arg_meta *meta)
 {
         return meta->kfunc_flags & KF_RELEASE;
 }
 
 static bool is_kfunc_trusted_args(struct bpf_kfunc_call_arg_meta *meta)
 {
         return (meta->kfunc_flags & KF_TRUSTED_ARGS) || is_kfunc_release(meta);
 }
 
 static bool is_kfunc_sleepable(struct bpf_kfunc_call_arg_meta *meta)
 {
         return meta->kfunc_flags & KF_SLEEPABLE;
 }
 
 static bool is_kfunc_destructive(struct bpf_kfunc_call_arg_meta *meta)
 {
         return meta->kfunc_flags & KF_DESTRUCTIVE;
 }
 
 static bool is_kfunc_rcu(struct bpf_kfunc_call_arg_meta *meta)
 {
         return meta->kfunc_flags & KF_RCU;
 }
 
 static bool is_kfunc_rcu_protected(struct bpf_kfunc_call_arg_meta *meta)
 {
         return meta->kfunc_flags & KF_RCU_PROTECTED;
 }
 
 static bool is_kfunc_arg_mem_size(const struct btf *btf,
                                   const struct btf_param *arg,
                                   const struct bpf_reg_state *reg)
 {
         const struct btf_type *t;
 
         t = btf_type_skip_modifiers(btf, arg->type, NULL);
         if (!btf_type_is_scalar(t) || reg->type != SCALAR_VALUE)
                 return false;
 
         return btf_param_match_suffix(btf, arg, "__sz");
 }
 
 static bool is_kfunc_arg_const_mem_size(const struct btf *btf,
                                         const struct btf_param *arg,
                                         const struct bpf_reg_state *reg)
 {
         const struct btf_type *t;
 
         t = btf_type_skip_modifiers(btf, arg->type, NULL);
         if (!btf_type_is_scalar(t) || reg->type != SCALAR_VALUE)
                 return false;
 
         return btf_param_match_suffix(btf, arg, "__szk");
 }
 
 static bool is_kfunc_arg_optional(const struct btf *btf, const struct btf_param *arg)
 {
         return btf_param_match_suffix(btf, arg, "__opt");
 }
 
 static bool is_kfunc_arg_constant(const struct btf *btf, const struct btf_param *arg)
 {
         return btf_param_match_suffix(btf, arg, "__k");
 }
 
 static bool is_kfunc_arg_ignore(const struct btf *btf, const struct btf_param *arg)
 {
         return btf_param_match_suffix(btf, arg, "__ign");
 }
 
 static bool is_kfunc_arg_map(const struct btf *btf, const struct btf_param *arg)
 {
         return btf_param_match_suffix(btf, arg, "__map");
 }
 
 static bool is_kfunc_arg_alloc_obj(const struct btf *btf, const struct btf_param *arg)
 {
         return btf_param_match_suffix(btf, arg, "__alloc");
 }
 
 static bool is_kfunc_arg_uninit(const struct btf *btf, const struct btf_param *arg)
 {
         return btf_param_match_suffix(btf, arg, "__uninit");
 }
 
 static bool is_kfunc_arg_refcounted_kptr(const struct btf *btf, const struct btf_param *arg)
 {
         return btf_param_match_suffix(btf, arg, "__refcounted_kptr");
 }
 
 static bool is_kfunc_arg_nullable(const struct btf *btf, const struct btf_param *arg)
 {
         return btf_param_match_suffix(btf, arg, "__nullable");
 }
 
 static bool is_kfunc_arg_const_str(const struct btf *btf, const struct btf_param *arg)
 {
         return btf_param_match_suffix(btf, arg, "__str");
 }
 
 static bool is_kfunc_arg_scalar_with_name(const struct btf *btf,
                                           const struct btf_param *arg,
                                           const char *name)
 {
         int len, target_len = strlen(name);
         const char *param_name;
 
         param_name = btf_name_by_offset(btf, arg->name_off);
         if (str_is_empty(param_name))
                 return false;
         len = strlen(param_name);
         if (len != target_len)
                 return false;
         if (strcmp(param_name, name))
                 return false;
 
         return true;
 }
 
 enum {
         KF_ARG_DYNPTR_ID,
         KF_ARG_LIST_HEAD_ID,
         KF_ARG_LIST_NODE_ID,
         KF_ARG_RB_ROOT_ID,
         KF_ARG_RB_NODE_ID,
         KF_ARG_WORKQUEUE_ID,
 };
 
 BTF_ID_LIST(kf_arg_btf_ids)
 BTF_ID(struct, bpf_dynptr)
 BTF_ID(struct, bpf_list_head)
 BTF_ID(struct, bpf_list_node)
 BTF_ID(struct, bpf_rb_root)
 BTF_ID(struct, bpf_rb_node)
 BTF_ID(struct, bpf_wq)
 
 static bool __is_kfunc_ptr_arg_type(const struct btf *btf,
                                     const struct btf_param *arg, int type)
 {
         const struct btf_type *t;
         u32 res_id;
 
         t = btf_type_skip_modifiers(btf, arg->type, NULL);
         if (!t)
                 return false;
         if (!btf_type_is_ptr(t))
                 return false;
         t = btf_type_skip_modifiers(btf, t->type, &res_id);
         if (!t)
                 return false;
         return btf_types_are_same(btf, res_id, btf_vmlinux, kf_arg_btf_ids[type]);
 }
 
 static bool is_kfunc_arg_dynptr(const struct btf *btf, const struct btf_param *arg)
 {
         return __is_kfunc_ptr_arg_type(btf, arg, KF_ARG_DYNPTR_ID);
 }
 
 static bool is_kfunc_arg_list_head(const struct btf *btf, const struct btf_param *arg)
 {
         return __is_kfunc_ptr_arg_type(btf, arg, KF_ARG_LIST_HEAD_ID);
 }
 
 static bool is_kfunc_arg_list_node(const struct btf *btf, const struct btf_param *arg)
 {
         return __is_kfunc_ptr_arg_type(btf, arg, KF_ARG_LIST_NODE_ID);
 }
 
 static bool is_kfunc_arg_rbtree_root(const struct btf *btf, const struct btf_param *arg)
 {
         return __is_kfunc_ptr_arg_type(btf, arg, KF_ARG_RB_ROOT_ID);
 }
 
 static bool is_kfunc_arg_rbtree_node(const struct btf *btf, const struct btf_param *arg)
 {
         return __is_kfunc_ptr_arg_type(btf, arg, KF_ARG_RB_NODE_ID);
 }
 
 static bool is_kfunc_arg_wq(const struct btf *btf, const struct btf_param *arg)
 {
         return __is_kfunc_ptr_arg_type(btf, arg, KF_ARG_WORKQUEUE_ID);
 }
 
 static bool is_kfunc_arg_callback(struct bpf_verifier_env *env, const struct btf *btf,
                                   const struct btf_param *arg)
 {
         const struct btf_type *t;
 
         t = btf_type_resolve_func_ptr(btf, arg->type, NULL);
         if (!t)
                 return false;
 
         return true;
 }
 
 /* Returns true if struct is composed of scalars, 4 levels of nesting allowed */
 static bool __btf_type_is_scalar_struct(struct bpf_verifier_env *env,
                                         const struct btf *btf,
                                         const struct btf_type *t, int rec)
 {
         const struct btf_type *member_type;
         const struct btf_member *member;
         u32 i;
 
         if (!btf_type_is_struct(t))
                 return false;
 
         for_each_member(i, t, member) {
                 const struct btf_array *array;
 
                 member_type = btf_type_skip_modifiers(btf, member->type, NULL);
                 if (btf_type_is_struct(member_type)) {
                         if (rec >= 3) {
                                 verbose(env, "max struct nesting depth exceeded\n");
                                 return false;
                         }
                         if (!__btf_type_is_scalar_struct(env, btf, member_type, rec + 1))
                                 return false;
                         continue;
                 }
                 if (btf_type_is_array(member_type)) {
                         array = btf_array(member_type);
                         if (!array->nelems)
                                 return false;
                         member_type = btf_type_skip_modifiers(btf, array->type, NULL);
                         if (!btf_type_is_scalar(member_type))
                                 return false;
                         continue;
                 }
                 if (!btf_type_is_scalar(member_type))
                         return false;
         }
         return true;
 }
 
 enum kfunc_ptr_arg_type {
         KF_ARG_PTR_TO_CTX,
         KF_ARG_PTR_TO_ALLOC_BTF_ID,    /* Allocated object */
         KF_ARG_PTR_TO_REFCOUNTED_KPTR, /* Refcounted local kptr */
         KF_ARG_PTR_TO_DYNPTR,
         KF_ARG_PTR_TO_ITER,
         KF_ARG_PTR_TO_LIST_HEAD,
         KF_ARG_PTR_TO_LIST_NODE,
         KF_ARG_PTR_TO_BTF_ID,          /* Also covers reg2btf_ids conversions */
         KF_ARG_PTR_TO_MEM,
         KF_ARG_PTR_TO_MEM_SIZE,        /* Size derived from next argument, skip it */
         KF_ARG_PTR_TO_CALLBACK,
         KF_ARG_PTR_TO_RB_ROOT,
         KF_ARG_PTR_TO_RB_NODE,
         KF_ARG_PTR_TO_NULL,
         KF_ARG_PTR_TO_CONST_STR,
         KF_ARG_PTR_TO_MAP,
         KF_ARG_PTR_TO_WORKQUEUE,
 };
 
 enum special_kfunc_type {
         KF_bpf_obj_new_impl,
         KF_bpf_obj_drop_impl,
         KF_bpf_refcount_acquire_impl,
         KF_bpf_list_push_front_impl,
         KF_bpf_list_push_back_impl,
         KF_bpf_list_pop_front,
         KF_bpf_list_pop_back,
         KF_bpf_cast_to_kern_ctx,
         KF_bpf_rdonly_cast,
         KF_bpf_rcu_read_lock,
         KF_bpf_rcu_read_unlock,
         KF_bpf_rbtree_remove,
         KF_bpf_rbtree_add_impl,
         KF_bpf_rbtree_first,
         KF_bpf_dynptr_from_skb,
         KF_bpf_dynptr_from_xdp,
         KF_bpf_dynptr_slice,
         KF_bpf_dynptr_slice_rdwr,
         KF_bpf_dynptr_clone,
         KF_bpf_percpu_obj_new_impl,
         KF_bpf_percpu_obj_drop_impl,
         KF_bpf_throw,
         KF_bpf_wq_set_callback_impl,
         KF_bpf_preempt_disable,
         KF_bpf_preempt_enable,
         KF_bpf_iter_css_task_new,
         KF_bpf_session_cookie,
 };
 
 BTF_SET_START(special_kfunc_set)
 BTF_ID(func, bpf_obj_new_impl)
 BTF_ID(func, bpf_obj_drop_impl)
 BTF_ID(func, bpf_refcount_acquire_impl)
 BTF_ID(func, bpf_list_push_front_impl)
 BTF_ID(func, bpf_list_push_back_impl)
 BTF_ID(func, bpf_list_pop_front)
 BTF_ID(func, bpf_list_pop_back)
 BTF_ID(func, bpf_cast_to_kern_ctx)
 BTF_ID(func, bpf_rdonly_cast)
 BTF_ID(func, bpf_rbtree_remove)
 BTF_ID(func, bpf_rbtree_add_impl)
 BTF_ID(func, bpf_rbtree_first)
 BTF_ID(func, bpf_dynptr_from_skb)
 BTF_ID(func, bpf_dynptr_from_xdp)
 BTF_ID(func, bpf_dynptr_slice)
 BTF_ID(func, bpf_dynptr_slice_rdwr)
 BTF_ID(func, bpf_dynptr_clone)
 BTF_ID(func, bpf_percpu_obj_new_impl)
 BTF_ID(func, bpf_percpu_obj_drop_impl)
 BTF_ID(func, bpf_throw)
 BTF_ID(func, bpf_wq_set_callback_impl)
 #ifdef CONFIG_CGROUPS
 BTF_ID(func, bpf_iter_css_task_new)
 #endif
 BTF_SET_END(special_kfunc_set)
 
 BTF_ID_LIST(special_kfunc_list)
 BTF_ID(func, bpf_obj_new_impl)
 BTF_ID(func, bpf_obj_drop_impl)
 BTF_ID(func, bpf_refcount_acquire_impl)
 BTF_ID(func, bpf_list_push_front_impl)
 BTF_ID(func, bpf_list_push_back_impl)
 BTF_ID(func, bpf_list_pop_front)
 BTF_ID(func, bpf_list_pop_back)
 BTF_ID(func, bpf_cast_to_kern_ctx)
 BTF_ID(func, bpf_rdonly_cast)
 BTF_ID(func, bpf_rcu_read_lock)
 BTF_ID(func, bpf_rcu_read_unlock)
 BTF_ID(func, bpf_rbtree_remove)
 BTF_ID(func, bpf_rbtree_add_impl)
 BTF_ID(func, bpf_rbtree_first)
 BTF_ID(func, bpf_dynptr_from_skb)
 BTF_ID(func, bpf_dynptr_from_xdp)
 BTF_ID(func, bpf_dynptr_slice)
 BTF_ID(func, bpf_dynptr_slice_rdwr)
 BTF_ID(func, bpf_dynptr_clone)
 BTF_ID(func, bpf_percpu_obj_new_impl)
 BTF_ID(func, bpf_percpu_obj_drop_impl)
 BTF_ID(func, bpf_throw)
 BTF_ID(func, bpf_wq_set_callback_impl)
 BTF_ID(func, bpf_preempt_disable)
 BTF_ID(func, bpf_preempt_enable)
 #ifdef CONFIG_CGROUPS
 BTF_ID(func, bpf_iter_css_task_new)
 #else
 BTF_ID_UNUSED
 #endif
 #ifdef CONFIG_BPF_EVENTS
 BTF_ID(func, bpf_session_cookie)
 #else
 BTF_ID_UNUSED
 #endif
 
 static bool is_kfunc_ret_null(struct bpf_kfunc_call_arg_meta *meta)
 {
         if (meta->func_id == special_kfunc_list[KF_bpf_refcount_acquire_impl] &&
             meta->arg_owning_ref) {
                 return false;
         }
 
         return meta->kfunc_flags & KF_RET_NULL;
 }
 
 static bool is_kfunc_bpf_rcu_read_lock(struct bpf_kfunc_call_arg_meta *meta)
 {
         return meta->func_id == special_kfunc_list[KF_bpf_rcu_read_lock];
 }
 
 static bool is_kfunc_bpf_rcu_read_unlock(struct bpf_kfunc_call_arg_meta *meta)
 {
         return meta->func_id == special_kfunc_list[KF_bpf_rcu_read_unlock];
 }
 
 static bool is_kfunc_bpf_preempt_disable(struct bpf_kfunc_call_arg_meta *meta)
 {
         return meta->func_id == special_kfunc_list[KF_bpf_preempt_disable];
 }
 
 static bool is_kfunc_bpf_preempt_enable(struct bpf_kfunc_call_arg_meta *meta)
 {
         return meta->func_id == special_kfunc_list[KF_bpf_preempt_enable];
 }
 
 static enum kfunc_ptr_arg_type
 get_kfunc_ptr_arg_type(struct bpf_verifier_env *env,
                        struct bpf_kfunc_call_arg_meta *meta,
                        const struct btf_type *t, const struct btf_type *ref_t,
                        const char *ref_tname, const struct btf_param *args,
                        int argno, int nargs)
 {
         u32 regno = argno + 1;
         struct bpf_reg_state *regs = cur_regs(env);
         struct bpf_reg_state *reg = &regs[regno];
         bool arg_mem_size = false;
 
         if (meta->func_id == special_kfunc_list[KF_bpf_cast_to_kern_ctx])
                 return KF_ARG_PTR_TO_CTX;
 
         /* In this function, we verify the kfunc's BTF as per the argument type,
          * leaving the rest of the verification with respect to the register
          * type to our caller. When a set of conditions hold in the BTF type of
          * arguments, we resolve it to a known kfunc_ptr_arg_type.
          */
         if (btf_is_prog_ctx_type(&env->log, meta->btf, t, resolve_prog_type(env->prog), argno))
                 return KF_ARG_PTR_TO_CTX;
 
         if (is_kfunc_arg_nullable(meta->btf, &args[argno]) && register_is_null(reg))
                 return KF_ARG_PTR_TO_NULL;
 
         if (is_kfunc_arg_alloc_obj(meta->btf, &args[argno]))
                 return KF_ARG_PTR_TO_ALLOC_BTF_ID;
 
         if (is_kfunc_arg_refcounted_kptr(meta->btf, &args[argno]))
                 return KF_ARG_PTR_TO_REFCOUNTED_KPTR;
 
         if (is_kfunc_arg_dynptr(meta->btf, &args[argno]))
                 return KF_ARG_PTR_TO_DYNPTR;
 
         if (is_kfunc_arg_iter(meta, argno))
                 return KF_ARG_PTR_TO_ITER;
 
         if (is_kfunc_arg_list_head(meta->btf, &args[argno]))
                 return KF_ARG_PTR_TO_LIST_HEAD;
 
         if (is_kfunc_arg_list_node(meta->btf, &args[argno]))
                 return KF_ARG_PTR_TO_LIST_NODE;
 
         if (is_kfunc_arg_rbtree_root(meta->btf, &args[argno]))
                 return KF_ARG_PTR_TO_RB_ROOT;
 
         if (is_kfunc_arg_rbtree_node(meta->btf, &args[argno]))
                 return KF_ARG_PTR_TO_RB_NODE;
 
         if (is_kfunc_arg_const_str(meta->btf, &args[argno]))
                 return KF_ARG_PTR_TO_CONST_STR;
 
         if (is_kfunc_arg_map(meta->btf, &args[argno]))
                 return KF_ARG_PTR_TO_MAP;
 
         if (is_kfunc_arg_wq(meta->btf, &args[argno]))
                 return KF_ARG_PTR_TO_WORKQUEUE;
 
         if ((base_type(reg->type) == PTR_TO_BTF_ID || reg2btf_ids[base_type(reg->type)])) {
                 if (!btf_type_is_struct(ref_t)) {
                         verbose(env, "kernel function %s args#%d pointer type %s %s is not supported\n",
                                 meta->func_name, argno, btf_type_str(ref_t), ref_tname);
                         return -EINVAL;
                 }
                 return KF_ARG_PTR_TO_BTF_ID;
         }
 
         if (is_kfunc_arg_callback(env, meta->btf, &args[argno]))
                 return KF_ARG_PTR_TO_CALLBACK;
 
         if (argno + 1 < nargs &&
             (is_kfunc_arg_mem_size(meta->btf, &args[argno + 1], &regs[regno + 1]) ||
              is_kfunc_arg_const_mem_size(meta->btf, &args[argno + 1], &regs[regno + 1])))
                 arg_mem_size = true;
 
         /* This is the catch all argument type of register types supported by
          * check_helper_mem_access. However, we only allow when argument type is
          * pointer to scalar, or struct composed (recursively) of scalars. When
          * arg_mem_size is true, the pointer can be void *.
          */
         if (!btf_type_is_scalar(ref_t) && !__btf_type_is_scalar_struct(env, meta->btf, ref_t, 0) &&
             (arg_mem_size ? !btf_type_is_void(ref_t) : 1)) {
                 verbose(env, "arg#%d pointer type %s %s must point to %sscalar, or struct with scalar\n",
                         argno, btf_type_str(ref_t), ref_tname, arg_mem_size ? "void, " : "");
                 return -EINVAL;
         }
         return arg_mem_size ? KF_ARG_PTR_TO_MEM_SIZE : KF_ARG_PTR_TO_MEM;
 }
 
 static int process_kf_arg_ptr_to_btf_id(struct bpf_verifier_env *env,
                                         struct bpf_reg_state *reg,
                                         const struct btf_type *ref_t,
                                         const char *ref_tname, u32 ref_id,
                                         struct bpf_kfunc_call_arg_meta *meta,
                                         int argno)
 {
         const struct btf_type *reg_ref_t;
         bool strict_type_match = false;
         const struct btf *reg_btf;
         const char *reg_ref_tname;
         bool taking_projection;
         bool struct_same;
         u32 reg_ref_id;
 
         if (base_type(reg->type) == PTR_TO_BTF_ID) {
                 reg_btf = reg->btf;
                 reg_ref_id = reg->btf_id;
         } else {
                 reg_btf = btf_vmlinux;
                 reg_ref_id = *reg2btf_ids[base_type(reg->type)];
         }
 
         /* Enforce strict type matching for calls to kfuncs that are acquiring
          * or releasing a reference, or are no-cast aliases. We do _not_
          * enforce strict matching for plain KF_TRUSTED_ARGS kfuncs by default,
          * as we want to enable BPF programs to pass types that are bitwise
          * equivalent without forcing them to explicitly cast with something
          * like bpf_cast_to_kern_ctx().
          *
          * For example, say we had a type like the following:
          *
          * struct bpf_cpumask {
          *      cpumask_t cpumask;
          *      refcount_t usage;
          * };
          *
          * Note that as specified in <linux/cpumask.h>, cpumask_t is typedef'ed
          * to a struct cpumask, so it would be safe to pass a struct
          * bpf_cpumask * to a kfunc expecting a struct cpumask *.
          *
          * The philosophy here is similar to how we allow scalars of different
          * types to be passed to kfuncs as long as the size is the same. The
          * only difference here is that we're simply allowing
          * btf_struct_ids_match() to walk the struct at the 0th offset, and
          * resolve types.
          */
         if (is_kfunc_acquire(meta) ||
             (is_kfunc_release(meta) && reg->ref_obj_id) ||
             btf_type_ids_nocast_alias(&env->log, reg_btf, reg_ref_id, meta->btf, ref_id))
                 strict_type_match = true;
 
         WARN_ON_ONCE(is_kfunc_release(meta) &&
                      (reg->off || !tnum_is_const(reg->var_off) ||
                       reg->var_off.value));
 
         reg_ref_t = btf_type_skip_modifiers(reg_btf, reg_ref_id, &reg_ref_id);
         reg_ref_tname = btf_name_by_offset(reg_btf, reg_ref_t->name_off);
         struct_same = btf_struct_ids_match(&env->log, reg_btf, reg_ref_id, reg->off, meta->btf, ref_id, strict_type_match);
         /* If kfunc is accepting a projection type (ie. __sk_buff), it cannot
          * actually use it -- it must cast to the underlying type. So we allow
          * caller to pass in the underlying type.
          */
         taking_projection = btf_is_projection_of(ref_tname, reg_ref_tname);
         if (!taking_projection && !struct_same) {
                 verbose(env, "kernel function %s args#%d expected pointer to %s %s but R%d has a pointer to %s %s\n",
                         meta->func_name, argno, btf_type_str(ref_t), ref_tname, argno + 1,
                         btf_type_str(reg_ref_t), reg_ref_tname);
                 return -EINVAL;
         }
         return 0;
 }
 
 static int ref_set_non_owning(struct bpf_verifier_env *env, struct bpf_reg_state *reg)
 {
         struct bpf_verifier_state *state = env->cur_state;
         struct btf_record *rec = reg_btf_record(reg);
 
         if (!state->active_lock.ptr) {
                 verbose(env, "verifier internal error: ref_set_non_owning w/o active lock\n");
                 return -EFAULT;
         }
 
         if (type_flag(reg->type) & NON_OWN_REF) {
                 verbose(env, "verifier internal error: NON_OWN_REF already set\n");
                 return -EFAULT;
         }
 
         reg->type |= NON_OWN_REF;
         if (rec->refcount_off >= 0)
                 reg->type |= MEM_RCU;
 
         return 0;
 }
 
 static int ref_convert_owning_non_owning(struct bpf_verifier_env *env, u32 ref_obj_id)
 {
         struct bpf_func_state *state, *unused;
         struct bpf_reg_state *reg;
         int i;
 
         state = cur_func(env);
 
         if (!ref_obj_id) {
                 verbose(env, "verifier internal error: ref_obj_id is zero for "
                              "owning -> non-owning conversion\n");
                 return -EFAULT;
         }
 
         for (i = 0; i < state->acquired_refs; i++) {
                 if (state->refs[i].id != ref_obj_id)
                         continue;
 
                 /* Clear ref_obj_id here so release_reference doesn't clobber
                  * the whole reg
                  */
                 bpf_for_each_reg_in_vstate(env->cur_state, unused, reg, ({
                         if (reg->ref_obj_id == ref_obj_id) {
                                 reg->ref_obj_id = 0;
                                 ref_set_non_owning(env, reg);
                         }
                 }));
                 return 0;
         }
 
         verbose(env, "verifier internal error: ref state missing for ref_obj_id\n");
         return -EFAULT;
 }
 
 /* Implementation details:
  *
  * Each register points to some region of memory, which we define as an
  * allocation. Each allocation may embed a bpf_spin_lock which protects any
  * special BPF objects (bpf_list_head, bpf_rb_root, etc.) part of the same
  * allocation. The lock and the data it protects are colocated in the same
  * memory region.
  *
  * Hence, everytime a register holds a pointer value pointing to such
  * allocation, the verifier preserves a unique reg->id for it.
  *
  * The verifier remembers the lock 'ptr' and the lock 'id' whenever
  * bpf_spin_lock is called.
  *
  * To enable this, lock state in the verifier captures two values:
  *      active_lock.ptr = Register's type specific pointer
  *      active_lock.id  = A unique ID for each register pointer value
  *
  * Currently, PTR_TO_MAP_VALUE and PTR_TO_BTF_ID | MEM_ALLOC are the two
  * supported register types.
  *
  * The active_lock.ptr in case of map values is the reg->map_ptr, and in case of
  * allocated objects is the reg->btf pointer.
  *
  * The active_lock.id is non-unique for maps supporting direct_value_addr, as we
  * can establish the provenance of the map value statically for each distinct
  * lookup into such maps. They always contain a single map value hence unique
  * IDs for each pseudo load pessimizes the algorithm and rejects valid programs.
  *
  * So, in case of global variables, they use array maps with max_entries = 1,
  * hence their active_lock.ptr becomes map_ptr and id = 0 (since they all point
  * into the same map value as max_entries is 1, as described above).
  *
  * In case of inner map lookups, the inner map pointer has same map_ptr as the
  * outer map pointer (in verifier context), but each lookup into an inner map
  * assigns a fresh reg->id to the lookup, so while lookups into distinct inner
  * maps from the same outer map share the same map_ptr as active_lock.ptr, they
  * will get different reg->id assigned to each lookup, hence different
  * active_lock.id.
  *
  * In case of allocated objects, active_lock.ptr is the reg->btf, and the
  * reg->id is a unique ID preserved after the NULL pointer check on the pointer
  * returned from bpf_obj_new. Each allocation receives a new reg->id.
  */
 static int check_reg_allocation_locked(struct bpf_verifier_env *env, struct bpf_reg_state *reg)
 {
         void *ptr;
         u32 id;
 
         switch ((int)reg->type) {
         case PTR_TO_MAP_VALUE:
                 ptr = reg->map_ptr;
                 break;
         case PTR_TO_BTF_ID | MEM_ALLOC:
                 ptr = reg->btf;
                 break;
         default:
                 verbose(env, "verifier internal error: unknown reg type for lock check\n");
                 return -EFAULT;
         }
         id = reg->id;
 
         if (!env->cur_state->active_lock.ptr)
                 return -EINVAL;
         if (env->cur_state->active_lock.ptr != ptr ||
             env->cur_state->active_lock.id != id) {
                 verbose(env, "held lock and object are not in the same allocation\n");
                 return -EINVAL;
         }
         return 0;
 }
 
 static bool is_bpf_list_api_kfunc(u32 btf_id)
 {
         return btf_id == special_kfunc_list[KF_bpf_list_push_front_impl] ||
                btf_id == special_kfunc_list[KF_bpf_list_push_back_impl] ||
                btf_id == special_kfunc_list[KF_bpf_list_pop_front] ||
                btf_id == special_kfunc_list[KF_bpf_list_pop_back];
 }
 
 static bool is_bpf_rbtree_api_kfunc(u32 btf_id)
 {
         return btf_id == special_kfunc_list[KF_bpf_rbtree_add_impl] ||
                btf_id == special_kfunc_list[KF_bpf_rbtree_remove] ||
                btf_id == special_kfunc_list[KF_bpf_rbtree_first];
 }
 
 static bool is_bpf_graph_api_kfunc(u32 btf_id)
 {
         return is_bpf_list_api_kfunc(btf_id) || is_bpf_rbtree_api_kfunc(btf_id) ||
                btf_id == special_kfunc_list[KF_bpf_refcount_acquire_impl];
 }
 
 static bool is_sync_callback_calling_kfunc(u32 btf_id)
 {
         return btf_id == special_kfunc_list[KF_bpf_rbtree_add_impl];
 }
 
 static bool is_async_callback_calling_kfunc(u32 btf_id)
 {
         return btf_id == special_kfunc_list[KF_bpf_wq_set_callback_impl];
 }
 
 static bool is_bpf_throw_kfunc(struct bpf_insn *insn)
 {
         return bpf_pseudo_kfunc_call(insn) && insn->off == 0 &&
                insn->imm == special_kfunc_list[KF_bpf_throw];
 }
 
 static bool is_bpf_wq_set_callback_impl_kfunc(u32 btf_id)
 {
         return btf_id == special_kfunc_list[KF_bpf_wq_set_callback_impl];
 }
 
 static bool is_callback_calling_kfunc(u32 btf_id)
 {
         return is_sync_callback_calling_kfunc(btf_id) ||
                is_async_callback_calling_kfunc(btf_id);
 }
 
 static bool is_rbtree_lock_required_kfunc(u32 btf_id)
 {
         return is_bpf_rbtree_api_kfunc(btf_id);
 }
 
 static bool check_kfunc_is_graph_root_api(struct bpf_verifier_env *env,
                                           enum btf_field_type head_field_type,
                                           u32 kfunc_btf_id)
 {
         bool ret;
 
         switch (head_field_type) {
         case BPF_LIST_HEAD:
                 ret = is_bpf_list_api_kfunc(kfunc_btf_id);
                 break;
         case BPF_RB_ROOT:
                 ret = is_bpf_rbtree_api_kfunc(kfunc_btf_id);
                 break;
         default:
                 verbose(env, "verifier internal error: unexpected graph root argument type %s\n",
                         btf_field_type_name(head_field_type));
                 return false;
         }
 
         if (!ret)
                 verbose(env, "verifier internal error: %s head arg for unknown kfunc\n",
                         btf_field_type_name(head_field_type));
         return ret;
 }
 
 static bool check_kfunc_is_graph_node_api(struct bpf_verifier_env *env,
                                           enum btf_field_type node_field_type,
                                           u32 kfunc_btf_id)
 {
         bool ret;
 
         switch (node_field_type) {
         case BPF_LIST_NODE:
                 ret = (kfunc_btf_id == special_kfunc_list[KF_bpf_list_push_front_impl] ||
                        kfunc_btf_id == special_kfunc_list[KF_bpf_list_push_back_impl]);
                 break;
         case BPF_RB_NODE:
                 ret = (kfunc_btf_id == special_kfunc_list[KF_bpf_rbtree_remove] ||
                        kfunc_btf_id == special_kfunc_list[KF_bpf_rbtree_add_impl]);
                 break;
         default:
                 verbose(env, "verifier internal error: unexpected graph node argument type %s\n",
                         btf_field_type_name(node_field_type));
                 return false;
         }
 
         if (!ret)
                 verbose(env, "verifier internal error: %s node arg for unknown kfunc\n",
                         btf_field_type_name(node_field_type));
         return ret;
 }
 
 static int
 __process_kf_arg_ptr_to_graph_root(struct bpf_verifier_env *env,
                                    struct bpf_reg_state *reg, u32 regno,
                                    struct bpf_kfunc_call_arg_meta *meta,
                                    enum btf_field_type head_field_type,
                                    struct btf_field **head_field)
 {
         const char *head_type_name;
         struct btf_field *field;
         struct btf_record *rec;
         u32 head_off;
 
         if (meta->btf != btf_vmlinux) {
                 verbose(env, "verifier internal error: unexpected btf mismatch in kfunc call\n");
                 return -EFAULT;
         }
 
         if (!check_kfunc_is_graph_root_api(env, head_field_type, meta->func_id))
                 return -EFAULT;
 
         head_type_name = btf_field_type_name(head_field_type);
         if (!tnum_is_const(reg->var_off)) {
                 verbose(env,
                         "R%d doesn't have constant offset. %s has to be at the constant offset\n",
                         regno, head_type_name);
                 return -EINVAL;
         }
 
         rec = reg_btf_record(reg);
         head_off = reg->off + reg->var_off.value;
         field = btf_record_find(rec, head_off, head_field_type);
         if (!field) {
                 verbose(env, "%s not found at offset=%u\n", head_type_name, head_off);
                 return -EINVAL;
         }
 
         /* All functions require bpf_list_head to be protected using a bpf_spin_lock */
         if (check_reg_allocation_locked(env, reg)) {
                 verbose(env, "bpf_spin_lock at off=%d must be held for %s\n",
                         rec->spin_lock_off, head_type_name);
                 return -EINVAL;
         }
 
         if (*head_field) {
                 verbose(env, "verifier internal error: repeating %s arg\n", head_type_name);
                 return -EFAULT;
         }
         *head_field = field;
         return 0;
 }
 
 static int process_kf_arg_ptr_to_list_head(struct bpf_verifier_env *env,
                                            struct bpf_reg_state *reg, u32 regno,
                                            struct bpf_kfunc_call_arg_meta *meta)
 {
         return __process_kf_arg_ptr_to_graph_root(env, reg, regno, meta, BPF_LIST_HEAD,
                                                           &meta->arg_list_head.field);
 }
 
 static int process_kf_arg_ptr_to_rbtree_root(struct bpf_verifier_env *env,
                                              struct bpf_reg_state *reg, u32 regno,
                                              struct bpf_kfunc_call_arg_meta *meta)
 {
         return __process_kf_arg_ptr_to_graph_root(env, reg, regno, meta, BPF_RB_ROOT,
                                                           &meta->arg_rbtree_root.field);
 }
 
 static int
 __process_kf_arg_ptr_to_graph_node(struct bpf_verifier_env *env,
                                    struct bpf_reg_state *reg, u32 regno,
                                    struct bpf_kfunc_call_arg_meta *meta,
                                    enum btf_field_type head_field_type,
                                    enum btf_field_type node_field_type,
                                    struct btf_field **node_field)
 {
         const char *node_type_name;
         const struct btf_type *et, *t;
         struct btf_field *field;
         u32 node_off;
 
         if (meta->btf != btf_vmlinux) {
                 verbose(env, "verifier internal error: unexpected btf mismatch in kfunc call\n");
                 return -EFAULT;
         }
 
         if (!check_kfunc_is_graph_node_api(env, node_field_type, meta->func_id))
                 return -EFAULT;
 
         node_type_name = btf_field_type_name(node_field_type);
         if (!tnum_is_const(reg->var_off)) {
                 verbose(env,
                         "R%d doesn't have constant offset. %s has to be at the constant offset\n",
                         regno, node_type_name);
                 return -EINVAL;
         }
 
         node_off = reg->off + reg->var_off.value;
         field = reg_find_field_offset(reg, node_off, node_field_type);
         if (!field) {
                 verbose(env, "%s not found at offset=%u\n", node_type_name, node_off);
                 return -EINVAL;
         }
 
         field = *node_field;
 
         et = btf_type_by_id(field->graph_root.btf, field->graph_root.value_btf_id);
         t = btf_type_by_id(reg->btf, reg->btf_id);
         if (!btf_struct_ids_match(&env->log, reg->btf, reg->btf_id, 0, field->graph_root.btf,
                                   field->graph_root.value_btf_id, true)) {
                 verbose(env, "operation on %s expects arg#1 %s at offset=%d "
                         "in struct %s, but arg is at offset=%d in struct %s\n",
                         btf_field_type_name(head_field_type),
                         btf_field_type_name(node_field_type),
                         field->graph_root.node_offset,
                         btf_name_by_offset(field->graph_root.btf, et->name_off),
                         node_off, btf_name_by_offset(reg->btf, t->name_off));
                 return -EINVAL;
         }
         meta->arg_btf = reg->btf;
         meta->arg_btf_id = reg->btf_id;
 
         if (node_off != field->graph_root.node_offset) {
                 verbose(env, "arg#1 offset=%d, but expected %s at offset=%d in struct %s\n",
                         node_off, btf_field_type_name(node_field_type),
                         field->graph_root.node_offset,
                         btf_name_by_offset(field->graph_root.btf, et->name_off));
                 return -EINVAL;
         }
 
         return 0;
 }
 
 static int process_kf_arg_ptr_to_list_node(struct bpf_verifier_env *env,
                                            struct bpf_reg_state *reg, u32 regno,
                                            struct bpf_kfunc_call_arg_meta *meta)
 {
         return __process_kf_arg_ptr_to_graph_node(env, reg, regno, meta,
                                                   BPF_LIST_HEAD, BPF_LIST_NODE,
                                                   &meta->arg_list_head.field);
 }
 
 static int process_kf_arg_ptr_to_rbtree_node(struct bpf_verifier_env *env,
                                              struct bpf_reg_state *reg, u32 regno,
                                              struct bpf_kfunc_call_arg_meta *meta)
 {
         return __process_kf_arg_ptr_to_graph_node(env, reg, regno, meta,
                                                   BPF_RB_ROOT, BPF_RB_NODE,
                                                   &meta->arg_rbtree_root.field);
 }
 
 /*
  * css_task iter allowlist is needed to avoid dead locking on css_set_lock.
  * LSM hooks and iters (both sleepable and non-sleepable) are safe.
  * Any sleepable progs are also safe since bpf_check_attach_target() enforce
  * them can only be attached to some specific hook points.
  */
 static bool check_css_task_iter_allowlist(struct bpf_verifier_env *env)
 {
         enum bpf_prog_type prog_type = resolve_prog_type(env->prog);
 
         switch (prog_type) {
         case BPF_PROG_TYPE_LSM:
                 return true;
         case BPF_PROG_TYPE_TRACING:
                 if (env->prog->expected_attach_type == BPF_TRACE_ITER)
                         return true;
                 fallthrough;
         default:
                 return in_sleepable(env);
         }
 }
 
 static int check_kfunc_args(struct bpf_verifier_env *env, struct bpf_kfunc_call_arg_meta *meta,
                             int insn_idx)
 {
         const char *func_name = meta->func_name, *ref_tname;
         const struct btf *btf = meta->btf;
         const struct btf_param *args;
         struct btf_record *rec;
         u32 i, nargs;
         int ret;
 
         args = (const struct btf_param *)(meta->func_proto + 1);
         nargs = btf_type_vlen(meta->func_proto);
         if (nargs > MAX_BPF_FUNC_REG_ARGS) {
                 verbose(env, "Function %s has %d > %d args\n", func_name, nargs,
                         MAX_BPF_FUNC_REG_ARGS);
                 return -EINVAL;
         }
 
         /* Check that BTF function arguments match actual types that the
          * verifier sees.
          */
         for (i = 0; i < nargs; i++) {
                 struct bpf_reg_state *regs = cur_regs(env), *reg = &regs[i + 1];
                 const struct btf_type *t, *ref_t, *resolve_ret;
                 enum bpf_arg_type arg_type = ARG_DONTCARE;
                 u32 regno = i + 1, ref_id, type_size;
                 bool is_ret_buf_sz = false;
                 int kf_arg_type;
 
                 t = btf_type_skip_modifiers(btf, args[i].type, NULL);
 
                 if (is_kfunc_arg_ignore(btf, &args[i]))
                         continue;
 
                 if (btf_type_is_scalar(t)) {
                         if (reg->type != SCALAR_VALUE) {
                                 verbose(env, "R%d is not a scalar\n", regno);
                                 return -EINVAL;
                         }
 
                         if (is_kfunc_arg_constant(meta->btf, &args[i])) {
                                 if (meta->arg_constant.found) {
                                         verbose(env, "verifier internal error: only one constant argument permitted\n");
                                         return -EFAULT;
                                 }
                                 if (!tnum_is_const(reg->var_off)) {
                                         verbose(env, "R%d must be a known constant\n", regno);
                                         return -EINVAL;
                                 }
                                 ret = mark_chain_precision(env, regno);
                                 if (ret < 0)
                                         return ret;
                                 meta->arg_constant.found = true;
                                 meta->arg_constant.value = reg->var_off.value;
                         } else if (is_kfunc_arg_scalar_with_name(btf, &args[i], "rdonly_buf_size")) {
                                 meta->r0_rdonly = true;
                                 is_ret_buf_sz = true;
                         } else if (is_kfunc_arg_scalar_with_name(btf, &args[i], "rdwr_buf_size")) {
                                 is_ret_buf_sz = true;
                         }
 
                         if (is_ret_buf_sz) {
                                 if (meta->r0_size) {
                                         verbose(env, "2 or more rdonly/rdwr_buf_size parameters for kfunc");
                                         return -EINVAL;
                                 }
 
                                 if (!tnum_is_const(reg->var_off)) {
                                         verbose(env, "R%d is not a const\n", regno);
                                         return -EINVAL;
                                 }
 
                                 meta->r0_size = reg->var_off.value;
                                 ret = mark_chain_precision(env, regno);
                                 if (ret)
                                         return ret;
                         }
                         continue;
                 }
 
                 if (!btf_type_is_ptr(t)) {
                         verbose(env, "Unrecognized arg#%d type %s\n", i, btf_type_str(t));
                         return -EINVAL;
                 }
 
                 if ((is_kfunc_trusted_args(meta) || is_kfunc_rcu(meta)) &&
                     (register_is_null(reg) || type_may_be_null(reg->type)) &&
                         !is_kfunc_arg_nullable(meta->btf, &args[i])) {
                         verbose(env, "Possibly NULL pointer passed to trusted arg%d\n", i);
                         return -EACCES;
                 }
 
                 if (reg->ref_obj_id) {
                         if (is_kfunc_release(meta) && meta->ref_obj_id) {
                                 verbose(env, "verifier internal error: more than one arg with ref_obj_id R%d %u %u\n",
                                         regno, reg->ref_obj_id,
                                         meta->ref_obj_id);
                                 return -EFAULT;
                         }
                         meta->ref_obj_id = reg->ref_obj_id;
                         if (is_kfunc_release(meta))
                                 meta->release_regno = regno;
                 }
 
                 ref_t = btf_type_skip_modifiers(btf, t->type, &ref_id);
                 ref_tname = btf_name_by_offset(btf, ref_t->name_off);
 
                 kf_arg_type = get_kfunc_ptr_arg_type(env, meta, t, ref_t, ref_tname, args, i, nargs);
                 if (kf_arg_type < 0)
                         return kf_arg_type;
 
                 switch (kf_arg_type) {
                 case KF_ARG_PTR_TO_NULL:
                         continue;
                 case KF_ARG_PTR_TO_MAP:
                         if (!reg->map_ptr) {
                                 verbose(env, "pointer in R%d isn't map pointer\n", regno);
                                 return -EINVAL;
                         }
                         if (meta->map.ptr && reg->map_ptr->record->wq_off >= 0) {
                                 /* Use map_uid (which is unique id of inner map) to reject:
                                  * inner_map1 = bpf_map_lookup_elem(outer_map, key1)
                                  * inner_map2 = bpf_map_lookup_elem(outer_map, key2)
                                  * if (inner_map1 && inner_map2) {
                                  *     wq = bpf_map_lookup_elem(inner_map1);
                                  *     if (wq)
                                  *         // mismatch would have been allowed
                                  *         bpf_wq_init(wq, inner_map2);
                                  * }
                                  *
                                  * Comparing map_ptr is enough to distinguish normal and outer maps.
                                  */
                                 if (meta->map.ptr != reg->map_ptr ||
                                     meta->map.uid != reg->map_uid) {
                                         verbose(env,
                                                 "workqueue pointer in R1 map_uid=%d doesn't match map pointer in R2 map_uid=%d\n",
                                                 meta->map.uid, reg->map_uid);
                                         return -EINVAL;
                                 }
                         }
                         meta->map.ptr = reg->map_ptr;
                         meta->map.uid = reg->map_uid;
                         fallthrough;
                 case KF_ARG_PTR_TO_ALLOC_BTF_ID:
                 case KF_ARG_PTR_TO_BTF_ID:
                         if (!is_kfunc_trusted_args(meta) && !is_kfunc_rcu(meta))
                                 break;
 
                         if (!is_trusted_reg(reg)) {
                                 if (!is_kfunc_rcu(meta)) {
                                         verbose(env, "R%d must be referenced or trusted\n", regno);
                                         return -EINVAL;
                                 }
                                 if (!is_rcu_reg(reg)) {
                                         verbose(env, "R%d must be a rcu pointer\n", regno);
                                         return -EINVAL;
                                 }
                         }
                         fallthrough;
                 case KF_ARG_PTR_TO_CTX:
                 case KF_ARG_PTR_TO_DYNPTR:
                 case KF_ARG_PTR_TO_ITER:
                 case KF_ARG_PTR_TO_LIST_HEAD:
                 case KF_ARG_PTR_TO_LIST_NODE:
                 case KF_ARG_PTR_TO_RB_ROOT:
                 case KF_ARG_PTR_TO_RB_NODE:
                 case KF_ARG_PTR_TO_MEM:
                 case KF_ARG_PTR_TO_MEM_SIZE:
                 case KF_ARG_PTR_TO_CALLBACK:
                 case KF_ARG_PTR_TO_REFCOUNTED_KPTR:
                 case KF_ARG_PTR_TO_CONST_STR:
                 case KF_ARG_PTR_TO_WORKQUEUE:
                         break;
                 default:
                         WARN_ON_ONCE(1);
                         return -EFAULT;
                 }
 
                 if (is_kfunc_release(meta) && reg->ref_obj_id)
                         arg_type |= OBJ_RELEASE;
                 ret = check_func_arg_reg_off(env, reg, regno, arg_type);
                 if (ret < 0)
                         return ret;
 
                 switch (kf_arg_type) {
                 case KF_ARG_PTR_TO_CTX:
                         if (reg->type != PTR_TO_CTX) {
                                 verbose(env, "arg#%d expected pointer to ctx, but got %s\n", i, btf_type_str(t));
                                 return -EINVAL;
                         }
 
                         if (meta->func_id == special_kfunc_list[KF_bpf_cast_to_kern_ctx]) {
                                 ret = get_kern_ctx_btf_id(&env->log, resolve_prog_type(env->prog));
                                 if (ret < 0)
                                         return -EINVAL;
                                 meta->ret_btf_id  = ret;
                         }
                         break;
                 case KF_ARG_PTR_TO_ALLOC_BTF_ID:
                         if (reg->type == (PTR_TO_BTF_ID | MEM_ALLOC)) {
                                 if (meta->func_id != special_kfunc_list[KF_bpf_obj_drop_impl]) {
                                         verbose(env, "arg#%d expected for bpf_obj_drop_impl()\n", i);
                                         return -EINVAL;
                                 }
                         } else if (reg->type == (PTR_TO_BTF_ID | MEM_ALLOC | MEM_PERCPU)) {
                                 if (meta->func_id != special_kfunc_list[KF_bpf_percpu_obj_drop_impl]) {
                                         verbose(env, "arg#%d expected for bpf_percpu_obj_drop_impl()\n", i);
                                         return -EINVAL;
                                 }
                         } else {
                                 verbose(env, "arg#%d expected pointer to allocated object\n", i);
                                 return -EINVAL;
                         }
                         if (!reg->ref_obj_id) {
                                 verbose(env, "allocated object must be referenced\n");
                                 return -EINVAL;
                         }
                         if (meta->btf == btf_vmlinux) {
                                 meta->arg_btf = reg->btf;
                                 meta->arg_btf_id = reg->btf_id;
                         }
                         break;
                 case KF_ARG_PTR_TO_DYNPTR:
                 {
                         enum bpf_arg_type dynptr_arg_type = ARG_PTR_TO_DYNPTR;
                         int clone_ref_obj_id = 0;
 
                         if (reg->type == CONST_PTR_TO_DYNPTR)
                                 dynptr_arg_type |= MEM_RDONLY;
 
                         if (is_kfunc_arg_uninit(btf, &args[i]))
                                 dynptr_arg_type |= MEM_UNINIT;
 
                         if (meta->func_id == special_kfunc_list[KF_bpf_dynptr_from_skb]) {
                                 dynptr_arg_type |= DYNPTR_TYPE_SKB;
                         } else if (meta->func_id == special_kfunc_list[KF_bpf_dynptr_from_xdp]) {
                                 dynptr_arg_type |= DYNPTR_TYPE_XDP;
                         } else if (meta->func_id == special_kfunc_list[KF_bpf_dynptr_clone] &&
                                    (dynptr_arg_type & MEM_UNINIT)) {
                                 enum bpf_dynptr_type parent_type = meta->initialized_dynptr.type;
 
                                 if (parent_type == BPF_DYNPTR_TYPE_INVALID) {
                                         verbose(env, "verifier internal error: no dynptr type for parent of clone\n");
                                         return -EFAULT;
                                 }
 
                                 dynptr_arg_type |= (unsigned int)get_dynptr_type_flag(parent_type);
                                 clone_ref_obj_id = meta->initialized_dynptr.ref_obj_id;
                                 if (dynptr_type_refcounted(parent_type) && !clone_ref_obj_id) {
                                         verbose(env, "verifier internal error: missing ref obj id for parent of clone\n");
                                         return -EFAULT;
                                 }
                         }
 
                         ret = process_dynptr_func(env, regno, insn_idx, dynptr_arg_type, clone_ref_obj_id);
                         if (ret < 0)
                                 return ret;
 
                         if (!(dynptr_arg_type & MEM_UNINIT)) {
                                 int id = dynptr_id(env, reg);
 
                                 if (id < 0) {
                                         verbose(env, "verifier internal error: failed to obtain dynptr id\n");
                                         return id;
                                 }
                                 meta->initialized_dynptr.id = id;
                                 meta->initialized_dynptr.type = dynptr_get_type(env, reg);
                                 meta->initialized_dynptr.ref_obj_id = dynptr_ref_obj_id(env, reg);
                         }
 
                         break;
                 }
                 case KF_ARG_PTR_TO_ITER:
                         if (meta->func_id == special_kfunc_list[KF_bpf_iter_css_task_new]) {
                                 if (!check_css_task_iter_allowlist(env)) {
                                         verbose(env, "css_task_iter is only allowed in bpf_lsm, bpf_iter and sleepable progs\n");
                                         return -EINVAL;
                                 }
                         }
                         ret = process_iter_arg(env, regno, insn_idx, meta);
                         if (ret < 0)
                                 return ret;
                         break;
                 case KF_ARG_PTR_TO_LIST_HEAD:
                         if (reg->type != PTR_TO_MAP_VALUE &&
                             reg->type != (PTR_TO_BTF_ID | MEM_ALLOC)) {
                                 verbose(env, "arg#%d expected pointer to map value or allocated object\n", i);
                                 return -EINVAL;
                         }
                         if (reg->type == (PTR_TO_BTF_ID | MEM_ALLOC) && !reg->ref_obj_id) {
                                 verbose(env, "allocated object must be referenced\n");
                                 return -EINVAL;
                         }
                         ret = process_kf_arg_ptr_to_list_head(env, reg, regno, meta);
                         if (ret < 0)
                                 return ret;
                         break;
                 case KF_ARG_PTR_TO_RB_ROOT:
                         if (reg->type != PTR_TO_MAP_VALUE &&
                             reg->type != (PTR_TO_BTF_ID | MEM_ALLOC)) {
                                 verbose(env, "arg#%d expected pointer to map value or allocated object\n", i);
                                 return -EINVAL;
                         }
                         if (reg->type == (PTR_TO_BTF_ID | MEM_ALLOC) && !reg->ref_obj_id) {
                                 verbose(env, "allocated object must be referenced\n");
                                 return -EINVAL;
                         }
                         ret = process_kf_arg_ptr_to_rbtree_root(env, reg, regno, meta);
                         if (ret < 0)
                                 return ret;
                         break;
                 case KF_ARG_PTR_TO_LIST_NODE:
                         if (reg->type != (PTR_TO_BTF_ID | MEM_ALLOC)) {
                                 verbose(env, "arg#%d expected pointer to allocated object\n", i);
                                 return -EINVAL;
                         }
                         if (!reg->ref_obj_id) {
                                 verbose(env, "allocated object must be referenced\n");
                                 return -EINVAL;
                         }
                         ret = process_kf_arg_ptr_to_list_node(env, reg, regno, meta);
                         if (ret < 0)
                                 return ret;
                         break;
                 case KF_ARG_PTR_TO_RB_NODE:
                         if (meta->func_id == special_kfunc_list[KF_bpf_rbtree_remove]) {
                                 if (!type_is_non_owning_ref(reg->type) || reg->ref_obj_id) {
                                         verbose(env, "rbtree_remove node input must be non-owning ref\n");
                                         return -EINVAL;
                                 }
                                 if (in_rbtree_lock_required_cb(env)) {
                                         verbose(env, "rbtree_remove not allowed in rbtree cb\n");
                                         return -EINVAL;
                                 }
                         } else {
                                 if (reg->type != (PTR_TO_BTF_ID | MEM_ALLOC)) {
                                         verbose(env, "arg#%d expected pointer to allocated object\n", i);
                                         return -EINVAL;
                                 }
                                 if (!reg->ref_obj_id) {
                                         verbose(env, "allocated object must be referenced\n");
                                         return -EINVAL;
                                 }
                         }
 
                         ret = process_kf_arg_ptr_to_rbtree_node(env, reg, regno, meta);
                         if (ret < 0)
                                 return ret;
                         break;
                 case KF_ARG_PTR_TO_MAP:
                         /* If argument has '__map' suffix expect 'struct bpf_map *' */
                         ref_id = *reg2btf_ids[CONST_PTR_TO_MAP];
                         ref_t = btf_type_by_id(btf_vmlinux, ref_id);
                         ref_tname = btf_name_by_offset(btf, ref_t->name_off);
                         fallthrough;
                 case KF_ARG_PTR_TO_BTF_ID:
                         /* Only base_type is checked, further checks are done here */
                         if ((base_type(reg->type) != PTR_TO_BTF_ID ||
                              (bpf_type_has_unsafe_modifiers(reg->type) && !is_rcu_reg(reg))) &&
                             !reg2btf_ids[base_type(reg->type)]) {
                                 verbose(env, "arg#%d is %s ", i, reg_type_str(env, reg->type));
                                 verbose(env, "expected %s or socket\n",
                                         reg_type_str(env, base_type(reg->type) |
                                                           (type_flag(reg->type) & BPF_REG_TRUSTED_MODIFIERS)));
                                 return -EINVAL;
                         }
                         ret = process_kf_arg_ptr_to_btf_id(env, reg, ref_t, ref_tname, ref_id, meta, i);
                         if (ret < 0)
                                 return ret;
                         break;
                 case KF_ARG_PTR_TO_MEM:
                         resolve_ret = btf_resolve_size(btf, ref_t, &type_size);
                         if (IS_ERR(resolve_ret)) {
                                 verbose(env, "arg#%d reference type('%s %s') size cannot be determined: %ld\n",
                                         i, btf_type_str(ref_t), ref_tname, PTR_ERR(resolve_ret));
                                 return -EINVAL;
                         }
                         ret = check_mem_reg(env, reg, regno, type_size);
                         if (ret < 0)
                                 return ret;
                         break;
                 case KF_ARG_PTR_TO_MEM_SIZE:
                 {
                         struct bpf_reg_state *buff_reg = &regs[regno];
                         const struct btf_param *buff_arg = &args[i];
                         struct bpf_reg_state *size_reg = &regs[regno + 1];
                         const struct btf_param *size_arg = &args[i + 1];
 
                         if (!register_is_null(buff_reg) || !is_kfunc_arg_optional(meta->btf, buff_arg)) {
                                 ret = check_kfunc_mem_size_reg(env, size_reg, regno + 1);
                                 if (ret < 0) {
                                         verbose(env, "arg#%d arg#%d memory, len pair leads to invalid memory access\n", i, i + 1);
                                         return ret;
                                 }
                         }
 
                         if (is_kfunc_arg_const_mem_size(meta->btf, size_arg, size_reg)) {
                                 if (meta->arg_constant.found) {
                                         verbose(env, "verifier internal error: only one constant argument permitted\n");
                                         return -EFAULT;
                                 }
                                 if (!tnum_is_const(size_reg->var_off)) {
                                         verbose(env, "R%d must be a known constant\n", regno + 1);
                                         return -EINVAL;
                                 }
                                 meta->arg_constant.found = true;
                                 meta->arg_constant.value = size_reg->var_off.value;
                         }
 
                         /* Skip next '__sz' or '__szk' argument */
                         i++;
                         break;
                 }
                 case KF_ARG_PTR_TO_CALLBACK:
                         if (reg->type != PTR_TO_FUNC) {
                                 verbose(env, "arg%d expected pointer to func\n", i);
                                 return -EINVAL;
                         }
                         meta->subprogno = reg->subprogno;
                         break;
                 case KF_ARG_PTR_TO_REFCOUNTED_KPTR:
                         if (!type_is_ptr_alloc_obj(reg->type)) {
                                 verbose(env, "arg#%d is neither owning or non-owning ref\n", i);
                                 return -EINVAL;
                         }
                         if (!type_is_non_owning_ref(reg->type))
                                 meta->arg_owning_ref = true;
 
                         rec = reg_btf_record(reg);
                         if (!rec) {
                                 verbose(env, "verifier internal error: Couldn't find btf_record\n");
                                 return -EFAULT;
                         }
 
                         if (rec->refcount_off < 0) {
                                 verbose(env, "arg#%d doesn't point to a type with bpf_refcount field\n", i);
                                 return -EINVAL;
                         }
 
                         meta->arg_btf = reg->btf;
                         meta->arg_btf_id = reg->btf_id;
                         break;
                 case KF_ARG_PTR_TO_CONST_STR:
                         if (reg->type != PTR_TO_MAP_VALUE) {
                                 verbose(env, "arg#%d doesn't point to a const string\n", i);
                                 return -EINVAL;
                         }
                         ret = check_reg_const_str(env, reg, regno);
                         if (ret)
                                 return ret;
                         break;
                 case KF_ARG_PTR_TO_WORKQUEUE:
                         if (reg->type != PTR_TO_MAP_VALUE) {
                                 verbose(env, "arg#%d doesn't point to a map value\n", i);
                                 return -EINVAL;
                         }
                         ret = process_wq_func(env, regno, meta);
                         if (ret < 0)
                                 return ret;
                         break;
                 }
         }
 
         if (is_kfunc_release(meta) && !meta->release_regno) {
                 verbose(env, "release kernel function %s expects refcounted PTR_TO_BTF_ID\n",
                         func_name);
                 return -EINVAL;
         }
 
         return 0;
 }
 
 static int fetch_kfunc_meta(struct bpf_verifier_env *env,
                             struct bpf_insn *insn,
                             struct bpf_kfunc_call_arg_meta *meta,
                             const char **kfunc_name)
 {
         const struct btf_type *func, *func_proto;
         u32 func_id, *kfunc_flags;
         const char *func_name;
         struct btf *desc_btf;
 
         if (kfunc_name)
                 *kfunc_name = NULL;
 
         if (!insn->imm)
                 return -EINVAL;
 
         desc_btf = find_kfunc_desc_btf(env, insn->off);
         if (IS_ERR(desc_btf))
                 return PTR_ERR(desc_btf);
 
         func_id = insn->imm;
         func = btf_type_by_id(desc_btf, func_id);
         func_name = btf_name_by_offset(desc_btf, func->name_off);
         if (kfunc_name)
                 *kfunc_name = func_name;
         func_proto = btf_type_by_id(desc_btf, func->type);
 
         kfunc_flags = btf_kfunc_id_set_contains(desc_btf, func_id, env->prog);
         if (!kfunc_flags) {
                 return -EACCES;
         }
 
         memset(meta, 0, sizeof(*meta));
         meta->btf = desc_btf;
         meta->func_id = func_id;
         meta->kfunc_flags = *kfunc_flags;
         meta->func_proto = func_proto;
         meta->func_name = func_name;
 
         return 0;
 }
 
 static int check_return_code(struct bpf_verifier_env *env, int regno, const char *reg_name);
 
 static int check_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
                             int *insn_idx_p)
 {
         bool sleepable, rcu_lock, rcu_unlock, preempt_disable, preempt_enable;
         u32 i, nargs, ptr_type_id, release_ref_obj_id;
         struct bpf_reg_state *regs = cur_regs(env);
         const char *func_name, *ptr_type_name;
         const struct btf_type *t, *ptr_type;
         struct bpf_kfunc_call_arg_meta meta;
         struct bpf_insn_aux_data *insn_aux;
         int err, insn_idx = *insn_idx_p;
         const struct btf_param *args;
         const struct btf_type *ret_t;
         struct btf *desc_btf;
 
         /* skip for now, but return error when we find this in fixup_kfunc_call */
         if (!insn->imm)
                 return 0;
 
         err = fetch_kfunc_meta(env, insn, &meta, &func_name);
         if (err == -EACCES && func_name)
                 verbose(env, "calling kernel function %s is not allowed\n", func_name);
         if (err)
                 return err;
         desc_btf = meta.btf;
         insn_aux = &env->insn_aux_data[insn_idx];
 
         insn_aux->is_iter_next = is_iter_next_kfunc(&meta);
 
         if (is_kfunc_destructive(&meta) && !capable(CAP_SYS_BOOT)) {
                 verbose(env, "destructive kfunc calls require CAP_SYS_BOOT capability\n");
                 return -EACCES;
         }
 
         sleepable = is_kfunc_sleepable(&meta);
         if (sleepable && !in_sleepable(env)) {
                 verbose(env, "program must be sleepable to call sleepable kfunc %s\n", func_name);
                 return -EACCES;
         }
 
         /* Check the arguments */
         err = check_kfunc_args(env, &meta, insn_idx);
         if (err < 0)
                 return err;
 
         if (meta.func_id == special_kfunc_list[KF_bpf_rbtree_add_impl]) {
                 err = push_callback_call(env, insn, insn_idx, meta.subprogno,
                                          set_rbtree_add_callback_state);
                 if (err) {
                         verbose(env, "kfunc %s#%d failed callback verification\n",
                                 func_name, meta.func_id);
                         return err;
                 }
         }
 
         if (meta.func_id == special_kfunc_list[KF_bpf_session_cookie]) {
                 meta.r0_size = sizeof(u64);
                 meta.r0_rdonly = false;
         }
 
         if (is_bpf_wq_set_callback_impl_kfunc(meta.func_id)) {
                 err = push_callback_call(env, insn, insn_idx, meta.subprogno,
                                          set_timer_callback_state);
                 if (err) {
                         verbose(env, "kfunc %s#%d failed callback verification\n",
                                 func_name, meta.func_id);
                         return err;
                 }
         }
 
         rcu_lock = is_kfunc_bpf_rcu_read_lock(&meta);
         rcu_unlock = is_kfunc_bpf_rcu_read_unlock(&meta);
 
         preempt_disable = is_kfunc_bpf_preempt_disable(&meta);
         preempt_enable = is_kfunc_bpf_preempt_enable(&meta);
 
         if (env->cur_state->active_rcu_lock) {
                 struct bpf_func_state *state;
                 struct bpf_reg_state *reg;
                 u32 clear_mask = (1 << STACK_SPILL) | (1 << STACK_ITER);
 
                 if (in_rbtree_lock_required_cb(env) && (rcu_lock || rcu_unlock)) {
                         verbose(env, "Calling bpf_rcu_read_{lock,unlock} in unnecessary rbtree callback\n");
                         return -EACCES;
                 }
 
                 if (rcu_lock) {
                         verbose(env, "nested rcu read lock (kernel function %s)\n", func_name);
                         return -EINVAL;
                 } else if (rcu_unlock) {
                         bpf_for_each_reg_in_vstate_mask(env->cur_state, state, reg, clear_mask, ({
                                 if (reg->type & MEM_RCU) {
                                         reg->type &= ~(MEM_RCU | PTR_MAYBE_NULL);
                                         reg->type |= PTR_UNTRUSTED;
                                 }
                         }));
                         env->cur_state->active_rcu_lock = false;
                 } else if (sleepable) {
                         verbose(env, "kernel func %s is sleepable within rcu_read_lock region\n", func_name);
                         return -EACCES;
                 }
         } else if (rcu_lock) {
                 env->cur_state->active_rcu_lock = true;
         } else if (rcu_unlock) {
                 verbose(env, "unmatched rcu read unlock (kernel function %s)\n", func_name);
                 return -EINVAL;
         }
 
         if (env->cur_state->active_preempt_lock) {
                 if (preempt_disable) {
                         env->cur_state->active_preempt_lock++;
                 } else if (preempt_enable) {
                         env->cur_state->active_preempt_lock--;
                 } else if (sleepable) {
                         verbose(env, "kernel func %s is sleepable within non-preemptible region\n", func_name);
                         return -EACCES;
                 }
         } else if (preempt_disable) {
                 env->cur_state->active_preempt_lock++;
         } else if (preempt_enable) {
                 verbose(env, "unmatched attempt to enable preemption (kernel function %s)\n", func_name);
                 return -EINVAL;
         }
 
         /* In case of release function, we get register number of refcounted
          * PTR_TO_BTF_ID in bpf_kfunc_arg_meta, do the release now.
          */
         if (meta.release_regno) {
                 err = release_reference(env, regs[meta.release_regno].ref_obj_id);
                 if (err) {
                         verbose(env, "kfunc %s#%d reference has not been acquired before\n",
                                 func_name, meta.func_id);
                         return err;
                 }
         }
 
         if (meta.func_id == special_kfunc_list[KF_bpf_list_push_front_impl] ||
             meta.func_id == special_kfunc_list[KF_bpf_list_push_back_impl] ||
             meta.func_id == special_kfunc_list[KF_bpf_rbtree_add_impl]) {
                 release_ref_obj_id = regs[BPF_REG_2].ref_obj_id;
                 insn_aux->insert_off = regs[BPF_REG_2].off;
                 insn_aux->kptr_struct_meta = btf_find_struct_meta(meta.arg_btf, meta.arg_btf_id);
                 err = ref_convert_owning_non_owning(env, release_ref_obj_id);
                 if (err) {
                         verbose(env, "kfunc %s#%d conversion of owning ref to non-owning failed\n",
                                 func_name, meta.func_id);
                         return err;
                 }
 
                 err = release_reference(env, release_ref_obj_id);
                 if (err) {
                         verbose(env, "kfunc %s#%d reference has not been acquired before\n",
                                 func_name, meta.func_id);
                         return err;
                 }
         }
 
         if (meta.func_id == special_kfunc_list[KF_bpf_throw]) {
                 if (!bpf_jit_supports_exceptions()) {
                         verbose(env, "JIT does not support calling kfunc %s#%d\n",
                                 func_name, meta.func_id);
                         return -ENOTSUPP;
                 }
                 env->seen_exception = true;
 
                 /* In the case of the default callback, the cookie value passed
                  * to bpf_throw becomes the return value of the program.
                  */
                 if (!env->exception_callback_subprog) {
                         err = check_return_code(env, BPF_REG_1, "R1");
                         if (err < 0)
                                 return err;
                 }
         }
 
         for (i = 0; i < CALLER_SAVED_REGS; i++)
                 mark_reg_not_init(env, regs, caller_saved[i]);
 
         /* Check return type */
         t = btf_type_skip_modifiers(desc_btf, meta.func_proto->type, NULL);
 
         if (is_kfunc_acquire(&meta) && !btf_type_is_struct_ptr(meta.btf, t)) {
                 /* Only exception is bpf_obj_new_impl */
                 if (meta.btf != btf_vmlinux ||
                     (meta.func_id != special_kfunc_list[KF_bpf_obj_new_impl] &&
                      meta.func_id != special_kfunc_list[KF_bpf_percpu_obj_new_impl] &&
                      meta.func_id != special_kfunc_list[KF_bpf_refcount_acquire_impl])) {
                         verbose(env, "acquire kernel function does not return PTR_TO_BTF_ID\n");
                         return -EINVAL;
                 }
         }
 
         if (btf_type_is_scalar(t)) {
                 mark_reg_unknown(env, regs, BPF_REG_0);
                 mark_btf_func_reg_size(env, BPF_REG_0, t->size);
         } else if (btf_type_is_ptr(t)) {
                 ptr_type = btf_type_skip_modifiers(desc_btf, t->type, &ptr_type_id);
 
                 if (meta.btf == btf_vmlinux && btf_id_set_contains(&special_kfunc_set, meta.func_id)) {
                         if (meta.func_id == special_kfunc_list[KF_bpf_obj_new_impl] ||
                             meta.func_id == special_kfunc_list[KF_bpf_percpu_obj_new_impl]) {
                                 struct btf_struct_meta *struct_meta;
                                 struct btf *ret_btf;
                                 u32 ret_btf_id;
 
                                 if (meta.func_id == special_kfunc_list[KF_bpf_obj_new_impl] && !bpf_global_ma_set)
                                         return -ENOMEM;
 
                                 if (((u64)(u32)meta.arg_constant.value) != meta.arg_constant.value) {
                                         verbose(env, "local type ID argument must be in range [0, U32_MAX]\n");
                                         return -EINVAL;
                                 }
 
                                 ret_btf = env->prog->aux->btf;
                                 ret_btf_id = meta.arg_constant.value;
 
                                 /* This may be NULL due to user not supplying a BTF */
                                 if (!ret_btf) {
                                         verbose(env, "bpf_obj_new/bpf_percpu_obj_new requires prog BTF\n");
                                         return -EINVAL;
                                 }
 
                                 ret_t = btf_type_by_id(ret_btf, ret_btf_id);
                                 if (!ret_t || !__btf_type_is_struct(ret_t)) {
                                         verbose(env, "bpf_obj_new/bpf_percpu_obj_new type ID argument must be of a struct\n");
                                         return -EINVAL;
                                 }
 
                                 if (meta.func_id == special_kfunc_list[KF_bpf_percpu_obj_new_impl]) {
                                         if (ret_t->size > BPF_GLOBAL_PERCPU_MA_MAX_SIZE) {
                                                 verbose(env, "bpf_percpu_obj_new type size (%d) is greater than %d\n",
                                                         ret_t->size, BPF_GLOBAL_PERCPU_MA_MAX_SIZE);
                                                 return -EINVAL;
                                         }
 
                                         if (!bpf_global_percpu_ma_set) {
                                                 mutex_lock(&bpf_percpu_ma_lock);
                                                 if (!bpf_global_percpu_ma_set) {
                                                         /* Charge memory allocated with bpf_global_percpu_ma to
                                                          * root memcg. The obj_cgroup for root memcg is NULL.
                                                          */
                                                         err = bpf_mem_alloc_percpu_init(&bpf_global_percpu_ma, NULL);
                                                         if (!err)
                                                                 bpf_global_percpu_ma_set = true;
                                                 }
                                                 mutex_unlock(&bpf_percpu_ma_lock);
                                                 if (err)
                                                         return err;
                                         }
 
                                         mutex_lock(&bpf_percpu_ma_lock);
                                         err = bpf_mem_alloc_percpu_unit_init(&bpf_global_percpu_ma, ret_t->size);
                                         mutex_unlock(&bpf_percpu_ma_lock);
                                         if (err)
                                                 return err;
                                 }
 
                                 struct_meta = btf_find_struct_meta(ret_btf, ret_btf_id);
                                 if (meta.func_id == special_kfunc_list[KF_bpf_percpu_obj_new_impl]) {
                                         if (!__btf_type_is_scalar_struct(env, ret_btf, ret_t, 0)) {
                                                 verbose(env, "bpf_percpu_obj_new type ID argument must be of a struct of scalars\n");
                                                 return -EINVAL;
                                         }
 
                                         if (struct_meta) {
                                                 verbose(env, "bpf_percpu_obj_new type ID argument must not contain special fields\n");
                                                 return -EINVAL;
                                         }
                                 }
 
                                 mark_reg_known_zero(env, regs, BPF_REG_0);
                                 regs[BPF_REG_0].type = PTR_TO_BTF_ID | MEM_ALLOC;
                                 regs[BPF_REG_0].btf = ret_btf;
                                 regs[BPF_REG_0].btf_id = ret_btf_id;
                                 if (meta.func_id == special_kfunc_list[KF_bpf_percpu_obj_new_impl])
                                         regs[BPF_REG_0].type |= MEM_PERCPU;
 
                                 insn_aux->obj_new_size = ret_t->size;
                                 insn_aux->kptr_struct_meta = struct_meta;
                         } else if (meta.func_id == special_kfunc_list[KF_bpf_refcount_acquire_impl]) {
                                 mark_reg_known_zero(env, regs, BPF_REG_0);
                                 regs[BPF_REG_0].type = PTR_TO_BTF_ID | MEM_ALLOC;
                                 regs[BPF_REG_0].btf = meta.arg_btf;
                                 regs[BPF_REG_0].btf_id = meta.arg_btf_id;
 
                                 insn_aux->kptr_struct_meta =
                                         btf_find_struct_meta(meta.arg_btf,
                                                              meta.arg_btf_id);
                         } else if (meta.func_id == special_kfunc_list[KF_bpf_list_pop_front] ||
                                    meta.func_id == special_kfunc_list[KF_bpf_list_pop_back]) {
                                 struct btf_field *field = meta.arg_list_head.field;
 
                                 mark_reg_graph_node(regs, BPF_REG_0, &field->graph_root);
                         } else if (meta.func_id == special_kfunc_list[KF_bpf_rbtree_remove] ||
                                    meta.func_id == special_kfunc_list[KF_bpf_rbtree_first]) {
                                 struct btf_field *field = meta.arg_rbtree_root.field;
 
                                 mark_reg_graph_node(regs, BPF_REG_0, &field->graph_root);
                         } else if (meta.func_id == special_kfunc_list[KF_bpf_cast_to_kern_ctx]) {
                                 mark_reg_known_zero(env, regs, BPF_REG_0);
                                 regs[BPF_REG_0].type = PTR_TO_BTF_ID | PTR_TRUSTED;
                                 regs[BPF_REG_0].btf = desc_btf;
                                 regs[BPF_REG_0].btf_id = meta.ret_btf_id;
                         } else if (meta.func_id == special_kfunc_list[KF_bpf_rdonly_cast]) {
                                 ret_t = btf_type_by_id(desc_btf, meta.arg_constant.value);
                                 if (!ret_t || !btf_type_is_struct(ret_t)) {
                                         verbose(env,
                                                 "kfunc bpf_rdonly_cast type ID argument must be of a struct\n");
                                         return -EINVAL;
                                 }
 
                                 mark_reg_known_zero(env, regs, BPF_REG_0);
                                 regs[BPF_REG_0].type = PTR_TO_BTF_ID | PTR_UNTRUSTED;
                                 regs[BPF_REG_0].btf = desc_btf;
                                 regs[BPF_REG_0].btf_id = meta.arg_constant.value;
                         } else if (meta.func_id == special_kfunc_list[KF_bpf_dynptr_slice] ||
                                    meta.func_id == special_kfunc_list[KF_bpf_dynptr_slice_rdwr]) {
                                 enum bpf_type_flag type_flag = get_dynptr_type_flag(meta.initialized_dynptr.type);
 
                                 mark_reg_known_zero(env, regs, BPF_REG_0);
 
                                 if (!meta.arg_constant.found) {
                                         verbose(env, "verifier internal error: bpf_dynptr_slice(_rdwr) no constant size\n");
                                         return -EFAULT;
                                 }
 
                                 regs[BPF_REG_0].mem_size = meta.arg_constant.value;
 
                                 /* PTR_MAYBE_NULL will be added when is_kfunc_ret_null is checked */
                                 regs[BPF_REG_0].type = PTR_TO_MEM | type_flag;
 
                                 if (meta.func_id == special_kfunc_list[KF_bpf_dynptr_slice]) {
                                         regs[BPF_REG_0].type |= MEM_RDONLY;
                                 } else {
                                         /* this will set env->seen_direct_write to true */
                                         if (!may_access_direct_pkt_data(env, NULL, BPF_WRITE)) {
                                                 verbose(env, "the prog does not allow writes to packet data\n");
                                                 return -EINVAL;
                                         }
                                 }
 
                                 if (!meta.initialized_dynptr.id) {
                                         verbose(env, "verifier internal error: no dynptr id\n");
                                         return -EFAULT;
                                 }
                                 regs[BPF_REG_0].dynptr_id = meta.initialized_dynptr.id;
 
                                 /* we don't need to set BPF_REG_0's ref obj id
                                  * because packet slices are not refcounted (see
                                  * dynptr_type_refcounted)
                                  */
                         } else {
                                 verbose(env, "kernel function %s unhandled dynamic return type\n",
                                         meta.func_name);
                                 return -EFAULT;
                         }
                 } else if (btf_type_is_void(ptr_type)) {
                         /* kfunc returning 'void *' is equivalent to returning scalar */
                         mark_reg_unknown(env, regs, BPF_REG_0);
                 } else if (!__btf_type_is_struct(ptr_type)) {
                         if (!meta.r0_size) {
                                 __u32 sz;
 
                                 if (!IS_ERR(btf_resolve_size(desc_btf, ptr_type, &sz))) {
                                         meta.r0_size = sz;
                                         meta.r0_rdonly = true;
                                 }
                         }
                         if (!meta.r0_size) {
                                 ptr_type_name = btf_name_by_offset(desc_btf,
                                                                    ptr_type->name_off);
                                 verbose(env,
                                         "kernel function %s returns pointer type %s %s is not supported\n",
                                         func_name,
                                         btf_type_str(ptr_type),
                                         ptr_type_name);
                                 return -EINVAL;
                         }
 
                         mark_reg_known_zero(env, regs, BPF_REG_0);
                         regs[BPF_REG_0].type = PTR_TO_MEM;
                         regs[BPF_REG_0].mem_size = meta.r0_size;
 
                         if (meta.r0_rdonly)
                                 regs[BPF_REG_0].type |= MEM_RDONLY;
 
                         /* Ensures we don't access the memory after a release_reference() */
                         if (meta.ref_obj_id)
                                 regs[BPF_REG_0].ref_obj_id = meta.ref_obj_id;
                 } else {
                         mark_reg_known_zero(env, regs, BPF_REG_0);
                         regs[BPF_REG_0].btf = desc_btf;
                         regs[BPF_REG_0].type = PTR_TO_BTF_ID;
                         regs[BPF_REG_0].btf_id = ptr_type_id;
 
                         if (is_iter_next_kfunc(&meta)) {
                                 struct bpf_reg_state *cur_iter;
 
                                 cur_iter = get_iter_from_state(env->cur_state, &meta);
 
                                 if (cur_iter->type & MEM_RCU) /* KF_RCU_PROTECTED */
                                         regs[BPF_REG_0].type |= MEM_RCU;
                                 else
                                         regs[BPF_REG_0].type |= PTR_TRUSTED;
                         }
                 }
 
                 if (is_kfunc_ret_null(&meta)) {
                         regs[BPF_REG_0].type |= PTR_MAYBE_NULL;
                         /* For mark_ptr_or_null_reg, see 93c230e3f5bd6 */
                         regs[BPF_REG_0].id = ++env->id_gen;
                 }
                 mark_btf_func_reg_size(env, BPF_REG_0, sizeof(void *));
                 if (is_kfunc_acquire(&meta)) {
                         int id = acquire_reference_state(env, insn_idx);
 
                         if (id < 0)
                                 return id;
                         if (is_kfunc_ret_null(&meta))
                                 regs[BPF_REG_0].id = id;
                         regs[BPF_REG_0].ref_obj_id = id;
                 } else if (meta.func_id == special_kfunc_list[KF_bpf_rbtree_first]) {
                         ref_set_non_owning(env, &regs[BPF_REG_0]);
                 }
 
                 if (reg_may_point_to_spin_lock(&regs[BPF_REG_0]) && !regs[BPF_REG_0].id)
                         regs[BPF_REG_0].id = ++env->id_gen;
         } else if (btf_type_is_void(t)) {
                 if (meta.btf == btf_vmlinux && btf_id_set_contains(&special_kfunc_set, meta.func_id)) {
                         if (meta.func_id == special_kfunc_list[KF_bpf_obj_drop_impl] ||
                             meta.func_id == special_kfunc_list[KF_bpf_percpu_obj_drop_impl]) {
                                 insn_aux->kptr_struct_meta =
                                         btf_find_struct_meta(meta.arg_btf,
                                                              meta.arg_btf_id);
                         }
                 }
         }
 
         nargs = btf_type_vlen(meta.func_proto);
         args = (const struct btf_param *)(meta.func_proto + 1);
         for (i = 0; i < nargs; i++) {
                 u32 regno = i + 1;
 
                 t = btf_type_skip_modifiers(desc_btf, args[i].type, NULL);
                 if (btf_type_is_ptr(t))
                         mark_btf_func_reg_size(env, regno, sizeof(void *));
                 else
                         /* scalar. ensured by btf_check_kfunc_arg_match() */
                         mark_btf_func_reg_size(env, regno, t->size);
         }
 
         if (is_iter_next_kfunc(&meta)) {
                 err = process_iter_next_call(env, insn_idx, &meta);
                 if (err)
                         return err;
         }
 
         return 0;
 }
 
 static bool check_reg_sane_offset(struct bpf_verifier_env *env,
                                   const struct bpf_reg_state *reg,
                                   enum bpf_reg_type type)
 {
         bool known = tnum_is_const(reg->var_off);
         s64 val = reg->var_off.value;
         s64 smin = reg->smin_value;
 
         if (known && (val >= BPF_MAX_VAR_OFF || val <= -BPF_MAX_VAR_OFF)) {
                 verbose(env, "math between %s pointer and %lld is not allowed\n",
                         reg_type_str(env, type), val);
                 return false;
         }
 
         if (reg->off >= BPF_MAX_VAR_OFF || reg->off <= -BPF_MAX_VAR_OFF) {
                 verbose(env, "%s pointer offset %d is not allowed\n",
                         reg_type_str(env, type), reg->off);
                 return false;
         }
 
         if (smin == S64_MIN) {
                 verbose(env, "math between %s pointer and register with unbounded min value is not allowed\n",
                         reg_type_str(env, type));
                 return false;
         }
 
         if (smin >= BPF_MAX_VAR_OFF || smin <= -BPF_MAX_VAR_OFF) {
                 verbose(env, "value %lld makes %s pointer be out of bounds\n",
                         smin, reg_type_str(env, type));
                 return false;
         }
 
         return true;
 }
 
 enum {
         REASON_BOUNDS   = -1,
         REASON_TYPE     = -2,
         REASON_PATHS    = -3,
         REASON_LIMIT    = -4,
         REASON_STACK    = -5,
 };
 
 static int retrieve_ptr_limit(const struct bpf_reg_state *ptr_reg,
                               u32 *alu_limit, bool mask_to_left)
 {
         u32 max = 0, ptr_limit = 0;
 
         switch (ptr_reg->type) {
         case PTR_TO_STACK:
                 /* Offset 0 is out-of-bounds, but acceptable start for the
                  * left direction, see BPF_REG_FP. Also, unknown scalar
                  * offset where we would need to deal with min/max bounds is
                  * currently prohibited for unprivileged.
                  */
                 max = MAX_BPF_STACK + mask_to_left;
                 ptr_limit = -(ptr_reg->var_off.value + ptr_reg->off);
                 break;
         case PTR_TO_MAP_VALUE:
                 max = ptr_reg->map_ptr->value_size;
                 ptr_limit = (mask_to_left ?
                              ptr_reg->smin_value :
                              ptr_reg->umax_value) + ptr_reg->off;
                 break;
         default:
                 return REASON_TYPE;
         }
 
         if (ptr_limit >= max)
                 return REASON_LIMIT;
         *alu_limit = ptr_limit;
         return 0;
 }
 
 static bool can_skip_alu_sanitation(const struct bpf_verifier_env *env,
                                     const struct bpf_insn *insn)
 {
         return env->bypass_spec_v1 || BPF_SRC(insn->code) == BPF_K;
 }
 
 static int update_alu_sanitation_state(struct bpf_insn_aux_data *aux,
                                        u32 alu_state, u32 alu_limit)
 {
         /* If we arrived here from different branches with different
          * state or limits to sanitize, then this won't work.
          */
         if (aux->alu_state &&
             (aux->alu_state != alu_state ||
              aux->alu_limit != alu_limit))
                 return REASON_PATHS;
 
         /* Corresponding fixup done in do_misc_fixups(). */
         aux->alu_state = alu_state;
         aux->alu_limit = alu_limit;
         return 0;
 }
 
 static int sanitize_val_alu(struct bpf_verifier_env *env,
                             struct bpf_insn *insn)
 {
         struct bpf_insn_aux_data *aux = cur_aux(env);
 
         if (can_skip_alu_sanitation(env, insn))
                 return 0;
 
         return update_alu_sanitation_state(aux, BPF_ALU_NON_POINTER, 0);
 }
 
 static bool sanitize_needed(u8 opcode)
 {
         return opcode == BPF_ADD || opcode == BPF_SUB;
 }
 
 struct bpf_sanitize_info {
         struct bpf_insn_aux_data aux;
         bool mask_to_left;
 };
 
 static struct bpf_verifier_state *
 sanitize_speculative_path(struct bpf_verifier_env *env,
                           const struct bpf_insn *insn,
                           u32 next_idx, u32 curr_idx)
 {
         struct bpf_verifier_state *branch;
         struct bpf_reg_state *regs;
 
         branch = push_stack(env, next_idx, curr_idx, true);
         if (branch && insn) {
                 regs = branch->frame[branch->curframe]->regs;
                 if (BPF_SRC(insn->code) == BPF_K) {
                         mark_reg_unknown(env, regs, insn->dst_reg);
                 } else if (BPF_SRC(insn->code) == BPF_X) {
                         mark_reg_unknown(env, regs, insn->dst_reg);
                         mark_reg_unknown(env, regs, insn->src_reg);
                 }
         }
         return branch;
 }
 
 static int sanitize_ptr_alu(struct bpf_verifier_env *env,
                             struct bpf_insn *insn,
                             const struct bpf_reg_state *ptr_reg,
                             const struct bpf_reg_state *off_reg,
                             struct bpf_reg_state *dst_reg,
                             struct bpf_sanitize_info *info,
                             const bool commit_window)
 {
         struct bpf_insn_aux_data *aux = commit_window ? cur_aux(env) : &info->aux;
         struct bpf_verifier_state *vstate = env->cur_state;
         bool off_is_imm = tnum_is_const(off_reg->var_off);
         bool off_is_neg = off_reg->smin_value < 0;
         bool ptr_is_dst_reg = ptr_reg == dst_reg;
         u8 opcode = BPF_OP(insn->code);
         u32 alu_state, alu_limit;
         struct bpf_reg_state tmp;
         bool ret;
         int err;
 
         if (can_skip_alu_sanitation(env, insn))
                 return 0;
 
         /* We already marked aux for masking from non-speculative
          * paths, thus we got here in the first place. We only care
          * to explore bad access from here.
          */
         if (vstate->speculative)
                 goto do_sim;
 
         if (!commit_window) {
                 if (!tnum_is_const(off_reg->var_off) &&
                     (off_reg->smin_value < 0) != (off_reg->smax_value < 0))
                         return REASON_BOUNDS;
 
                 info->mask_to_left = (opcode == BPF_ADD &&  off_is_neg) ||
                                      (opcode == BPF_SUB && !off_is_neg);
         }
 
         err = retrieve_ptr_limit(ptr_reg, &alu_limit, info->mask_to_left);
         if (err < 0)
                 return err;
 
         if (commit_window) {
                 /* In commit phase we narrow the masking window based on
                  * the observed pointer move after the simulated operation.
                  */
                 alu_state = info->aux.alu_state;
                 alu_limit = abs(info->aux.alu_limit - alu_limit);
         } else {
                 alu_state  = off_is_neg ? BPF_ALU_NEG_VALUE : 0;
                 alu_state |= off_is_imm ? BPF_ALU_IMMEDIATE : 0;
                 alu_state |= ptr_is_dst_reg ?
                              BPF_ALU_SANITIZE_SRC : BPF_ALU_SANITIZE_DST;
 
                 /* Limit pruning on unknown scalars to enable deep search for
                  * potential masking differences from other program paths.
                  */
                 if (!off_is_imm)
                         env->explore_alu_limits = true;
         }
 
         err = update_alu_sanitation_state(aux, alu_state, alu_limit);
         if (err < 0)
                 return err;
 do_sim:
         /* If we're in commit phase, we're done here given we already
          * pushed the truncated dst_reg into the speculative verification
          * stack.
          *
          * Also, when register is a known constant, we rewrite register-based
          * operation to immediate-based, and thus do not need masking (and as
          * a consequence, do not need to simulate the zero-truncation either).
          */
         if (commit_window || off_is_imm)
                 return 0;
 
         /* Simulate and find potential out-of-bounds access under
          * speculative execution from truncation as a result of
          * masking when off was not within expected range. If off
          * sits in dst, then we temporarily need to move ptr there
          * to simulate dst (== 0) +/-= ptr. Needed, for example,
          * for cases where we use K-based arithmetic in one direction
          * and truncated reg-based in the other in order to explore
          * bad access.
          */
         if (!ptr_is_dst_reg) {
                 tmp = *dst_reg;
                 copy_register_state(dst_reg, ptr_reg);
         }
         ret = sanitize_speculative_path(env, NULL, env->insn_idx + 1,
                                         env->insn_idx);
         if (!ptr_is_dst_reg && ret)
                 *dst_reg = tmp;
         return !ret ? REASON_STACK : 0;
 }
 
 static void sanitize_mark_insn_seen(struct bpf_verifier_env *env)
 {
         struct bpf_verifier_state *vstate = env->cur_state;
 
         /* If we simulate paths under speculation, we don't update the
          * insn as 'seen' such that when we verify unreachable paths in
          * the non-speculative domain, sanitize_dead_code() can still
          * rewrite/sanitize them.
          */
         if (!vstate->speculative)
                 env->insn_aux_data[env->insn_idx].seen = env->pass_cnt;
 }
 
 static int sanitize_err(struct bpf_verifier_env *env,
                         const struct bpf_insn *insn, int reason,
                         const struct bpf_reg_state *off_reg,
                         const struct bpf_reg_state *dst_reg)
 {
         static const char *err = "pointer arithmetic with it prohibited for !root";
         const char *op = BPF_OP(insn->code) == BPF_ADD ? "add" : "sub";
         u32 dst = insn->dst_reg, src = insn->src_reg;
 
         switch (reason) {
         case REASON_BOUNDS:
                 verbose(env, "R%d has unknown scalar with mixed signed bounds, %s\n",
                         off_reg == dst_reg ? dst : src, err);
                 break;
         case REASON_TYPE:
                 verbose(env, "R%d has pointer with unsupported alu operation, %s\n",
                         off_reg == dst_reg ? src : dst, err);
                 break;
         case REASON_PATHS:
                 verbose(env, "R%d tried to %s from different maps, paths or scalars, %s\n",
                         dst, op, err);
                 break;
         case REASON_LIMIT:
                 verbose(env, "R%d tried to %s beyond pointer bounds, %s\n",
                         dst, op, err);
                 break;
         case REASON_STACK:
                 verbose(env, "R%d could not be pushed for speculative verification, %s\n",
                         dst, err);
                 break;
         default:
                 verbose(env, "verifier internal error: unknown reason (%d)\n",
                         reason);
                 break;
         }
 
         return -EACCES;
 }
 
 /* check that stack access falls within stack limits and that 'reg' doesn't
  * have a variable offset.
  *
  * Variable offset is prohibited for unprivileged mode for simplicity since it
  * requires corresponding support in Spectre masking for stack ALU.  See also
  * retrieve_ptr_limit().
  *
  *
  * 'off' includes 'reg->off'.
  */
 static int check_stack_access_for_ptr_arithmetic(
                                 struct bpf_verifier_env *env,
                                 int regno,
                                 const struct bpf_reg_state *reg,
                                 int off)
 {
         if (!tnum_is_const(reg->var_off)) {
                 char tn_buf[48];
 
                 tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
                 verbose(env, "R%d variable stack access prohibited for !root, var_off=%s off=%d\n",
                         regno, tn_buf, off);
                 return -EACCES;
         }
 
         if (off >= 0 || off < -MAX_BPF_STACK) {
                 verbose(env, "R%d stack pointer arithmetic goes out of range, "
                         "prohibited for !root; off=%d\n", regno, off);
                 return -EACCES;
         }
 
         return 0;
 }
 
 static int sanitize_check_bounds(struct bpf_verifier_env *env,
                                  const struct bpf_insn *insn,
                                  const struct bpf_reg_state *dst_reg)
 {
         u32 dst = insn->dst_reg;
 
         /* For unprivileged we require that resulting offset must be in bounds
          * in order to be able to sanitize access later on.
          */
         if (env->bypass_spec_v1)
                 return 0;
 
         switch (dst_reg->type) {
         case PTR_TO_STACK:
                 if (check_stack_access_for_ptr_arithmetic(env, dst, dst_reg,
                                         dst_reg->off + dst_reg->var_off.value))
                         return -EACCES;
                 break;
         case PTR_TO_MAP_VALUE:
                 if (check_map_access(env, dst, dst_reg->off, 1, false, ACCESS_HELPER)) {
                         verbose(env, "R%d pointer arithmetic of map value goes out of range, "
                                 "prohibited for !root\n", dst);
                         return -EACCES;
                 }
                 break;
         default:
                 break;
         }
 
         return 0;
 }
 
 /* Handles arithmetic on a pointer and a scalar: computes new min/max and var_off.
  * Caller should also handle BPF_MOV case separately.
  * If we return -EACCES, caller may want to try again treating pointer as a
  * scalar.  So we only emit a diagnostic if !env->allow_ptr_leaks.
  */
 static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env,
                                    struct bpf_insn *insn,
                                    const struct bpf_reg_state *ptr_reg,
                                    const struct bpf_reg_state *off_reg)
 {
         struct bpf_verifier_state *vstate = env->cur_state;
         struct bpf_func_state *state = vstate->frame[vstate->curframe];
         struct bpf_reg_state *regs = state->regs, *dst_reg;
         bool known = tnum_is_const(off_reg->var_off);
         s64 smin_val = off_reg->smin_value, smax_val = off_reg->smax_value,
             smin_ptr = ptr_reg->smin_value, smax_ptr = ptr_reg->smax_value;
         u64 umin_val = off_reg->umin_value, umax_val = off_reg->umax_value,
             umin_ptr = ptr_reg->umin_value, umax_ptr = ptr_reg->umax_value;
         struct bpf_sanitize_info info = {};
         u8 opcode = BPF_OP(insn->code);
         u32 dst = insn->dst_reg;
         int ret;
 
         dst_reg = &regs[dst];
 
         if ((known && (smin_val != smax_val || umin_val != umax_val)) ||
             smin_val > smax_val || umin_val > umax_val) {
                 /* Taint dst register if offset had invalid bounds derived from
                  * e.g. dead branches.
                  */
                 __mark_reg_unknown(env, dst_reg);
                 return 0;
         }
 
         if (BPF_CLASS(insn->code) != BPF_ALU64) {
                 /* 32-bit ALU ops on pointers produce (meaningless) scalars */
                 if (opcode == BPF_SUB && env->allow_ptr_leaks) {
                         __mark_reg_unknown(env, dst_reg);
                         return 0;
                 }
 
                 verbose(env,
                         "R%d 32-bit pointer arithmetic prohibited\n",
                         dst);
                 return -EACCES;
         }
 
         if (ptr_reg->type & PTR_MAYBE_NULL) {
                 verbose(env, "R%d pointer arithmetic on %s prohibited, null-check it first\n",
                         dst, reg_type_str(env, ptr_reg->type));
                 return -EACCES;
         }
 
         switch (base_type(ptr_reg->type)) {
         case PTR_TO_CTX:
         case PTR_TO_MAP_VALUE:
         case PTR_TO_MAP_KEY:
         case PTR_TO_STACK:
         case PTR_TO_PACKET_META:
         case PTR_TO_PACKET:
         case PTR_TO_TP_BUFFER:
         case PTR_TO_BTF_ID:
         case PTR_TO_MEM:
         case PTR_TO_BUF:
         case PTR_TO_FUNC:
         case CONST_PTR_TO_DYNPTR:
                 break;
         case PTR_TO_FLOW_KEYS:
                 if (known)
                         break;
                 fallthrough;
         case CONST_PTR_TO_MAP:
                 /* smin_val represents the known value */
                 if (known && smin_val == 0 && opcode == BPF_ADD)
                         break;
                 fallthrough;
         default:
                 verbose(env, "R%d pointer arithmetic on %s prohibited\n",
                         dst, reg_type_str(env, ptr_reg->type));
                 return -EACCES;
         }
 
         /* In case of 'scalar += pointer', dst_reg inherits pointer type and id.
          * The id may be overwritten later if we create a new variable offset.
          */
         dst_reg->type = ptr_reg->type;
         dst_reg->id = ptr_reg->id;
 
         if (!check_reg_sane_offset(env, off_reg, ptr_reg->type) ||
             !check_reg_sane_offset(env, ptr_reg, ptr_reg->type))
                 return -EINVAL;
 
         /* pointer types do not carry 32-bit bounds at the moment. */
         __mark_reg32_unbounded(dst_reg);
 
         if (sanitize_needed(opcode)) {
                 ret = sanitize_ptr_alu(env, insn, ptr_reg, off_reg, dst_reg,
                                        &info, false);
                 if (ret < 0)
                         return sanitize_err(env, insn, ret, off_reg, dst_reg);
         }
 
         switch (opcode) {
         case BPF_ADD:
                 /* We can take a fixed offset as long as it doesn't overflow
                  * the s32 'off' field
                  */
                 if (known && (ptr_reg->off + smin_val ==
                               (s64)(s32)(ptr_reg->off + smin_val))) {
                         /* pointer += K.  Accumulate it into fixed offset */
                         dst_reg->smin_value = smin_ptr;
                         dst_reg->smax_value = smax_ptr;
                         dst_reg->umin_value = umin_ptr;
                         dst_reg->umax_value = umax_ptr;
                         dst_reg->var_off = ptr_reg->var_off;
                         dst_reg->off = ptr_reg->off + smin_val;
                         dst_reg->raw = ptr_reg->raw;
                         break;
                 }
                 /* A new variable offset is created.  Note that off_reg->off
                  * == 0, since it's a scalar.
                  * dst_reg gets the pointer type and since some positive
                  * integer value was added to the pointer, give it a new 'id'
                  * if it's a PTR_TO_PACKET.
                  * this creates a new 'base' pointer, off_reg (variable) gets
                  * added into the variable offset, and we copy the fixed offset
                  * from ptr_reg.
                  */
                 if (check_add_overflow(smin_ptr, smin_val, &dst_reg->smin_value) ||
                     check_add_overflow(smax_ptr, smax_val, &dst_reg->smax_value)) {
                         dst_reg->smin_value = S64_MIN;
                         dst_reg->smax_value = S64_MAX;
                 }
                 if (check_add_overflow(umin_ptr, umin_val, &dst_reg->umin_value) ||
                     check_add_overflow(umax_ptr, umax_val, &dst_reg->umax_value)) {
                         dst_reg->umin_value = 0;
                         dst_reg->umax_value = U64_MAX;
                 }
                 dst_reg->var_off = tnum_add(ptr_reg->var_off, off_reg->var_off);
                 dst_reg->off = ptr_reg->off;
                 dst_reg->raw = ptr_reg->raw;
                 if (reg_is_pkt_pointer(ptr_reg)) {
                         dst_reg->id = ++env->id_gen;
                         /* something was added to pkt_ptr, set range to zero */
                         memset(&dst_reg->raw, 0, sizeof(dst_reg->raw));
                 }
                 break;
         case BPF_SUB:
                 if (dst_reg == off_reg) {
                         /* scalar -= pointer.  Creates an unknown scalar */
                         verbose(env, "R%d tried to subtract pointer from scalar\n",
                                 dst);
                         return -EACCES;
                 }
                 /* We don't allow subtraction from FP, because (according to
                  * test_verifier.c test "invalid fp arithmetic", JITs might not
                  * be able to deal with it.
                  */
                 if (ptr_reg->type == PTR_TO_STACK) {
                         verbose(env, "R%d subtraction from stack pointer prohibited\n",
                                 dst);
                         return -EACCES;
                 }
                 if (known && (ptr_reg->off - smin_val ==
                               (s64)(s32)(ptr_reg->off - smin_val))) {
                         /* pointer -= K.  Subtract it from fixed offset */
                         dst_reg->smin_value = smin_ptr;
                         dst_reg->smax_value = smax_ptr;
                         dst_reg->umin_value = umin_ptr;
                         dst_reg->umax_value = umax_ptr;
                         dst_reg->var_off = ptr_reg->var_off;
                         dst_reg->id = ptr_reg->id;
                         dst_reg->off = ptr_reg->off - smin_val;
                         dst_reg->raw = ptr_reg->raw;
                         break;
                 }
                 /* A new variable offset is created.  If the subtrahend is known
                  * nonnegative, then any reg->range we had before is still good.
                  */
                 if (check_sub_overflow(smin_ptr, smax_val, &dst_reg->smin_value) ||
                     check_sub_overflow(smax_ptr, smin_val, &dst_reg->smax_value)) {
                         /* Overflow possible, we know nothing */
                         dst_reg->smin_value = S64_MIN;
                         dst_reg->smax_value = S64_MAX;
                 }
                 if (umin_ptr < umax_val) {
                         /* Overflow possible, we know nothing */
                         dst_reg->umin_value = 0;
                         dst_reg->umax_value = U64_MAX;
                 } else {
                         /* Cannot overflow (as long as bounds are consistent) */
                         dst_reg->umin_value = umin_ptr - umax_val;
                         dst_reg->umax_value = umax_ptr - umin_val;
                 }
                 dst_reg->var_off = tnum_sub(ptr_reg->var_off, off_reg->var_off);
                 dst_reg->off = ptr_reg->off;
                 dst_reg->raw = ptr_reg->raw;
                 if (reg_is_pkt_pointer(ptr_reg)) {
                         dst_reg->id = ++env->id_gen;
                         /* something was added to pkt_ptr, set range to zero */
                         if (smin_val < 0)
                                 memset(&dst_reg->raw, 0, sizeof(dst_reg->raw));
                 }
                 break;
         case BPF_AND:
         case BPF_OR:
         case BPF_XOR:
                 /* bitwise ops on pointers are troublesome, prohibit. */
                 verbose(env, "R%d bitwise operator %s on pointer prohibited\n",
                         dst, bpf_alu_string[opcode >> 4]);
                 return -EACCES;
         default:
                 /* other operators (e.g. MUL,LSH) produce non-pointer results */
                 verbose(env, "R%d pointer arithmetic with %s operator prohibited\n",
                         dst, bpf_alu_string[opcode >> 4]);
                 return -EACCES;
         }
 
         if (!check_reg_sane_offset(env, dst_reg, ptr_reg->type))
                 return -EINVAL;
         reg_bounds_sync(dst_reg);
         if (sanitize_check_bounds(env, insn, dst_reg) < 0)
                 return -EACCES;
         if (sanitize_needed(opcode)) {
                 ret = sanitize_ptr_alu(env, insn, dst_reg, off_reg, dst_reg,
                                        &info, true);
                 if (ret < 0)
                         return sanitize_err(env, insn, ret, off_reg, dst_reg);
         }
 
         return 0;
 }
 
 static void scalar32_min_max_add(struct bpf_reg_state *dst_reg,
                                  struct bpf_reg_state *src_reg)
 {
         s32 *dst_smin = &dst_reg->s32_min_value;
         s32 *dst_smax = &dst_reg->s32_max_value;
         u32 *dst_umin = &dst_reg->u32_min_value;
         u32 *dst_umax = &dst_reg->u32_max_value;
 
         if (check_add_overflow(*dst_smin, src_reg->s32_min_value, dst_smin) ||
             check_add_overflow(*dst_smax, src_reg->s32_max_value, dst_smax)) {
                 *dst_smin = S32_MIN;
                 *dst_smax = S32_MAX;
         }
         if (check_add_overflow(*dst_umin, src_reg->u32_min_value, dst_umin) ||
             check_add_overflow(*dst_umax, src_reg->u32_max_value, dst_umax)) {
                 *dst_umin = 0;
                 *dst_umax = U32_MAX;
         }
 }
 
 static void scalar_min_max_add(struct bpf_reg_state *dst_reg,
                                struct bpf_reg_state *src_reg)
 {
         s64 *dst_smin = &dst_reg->smin_value;
         s64 *dst_smax = &dst_reg->smax_value;
         u64 *dst_umin = &dst_reg->umin_value;
         u64 *dst_umax = &dst_reg->umax_value;
 
         if (check_add_overflow(*dst_smin, src_reg->smin_value, dst_smin) ||
             check_add_overflow(*dst_smax, src_reg->smax_value, dst_smax)) {
                 *dst_smin = S64_MIN;
                 *dst_smax = S64_MAX;
         }
         if (check_add_overflow(*dst_umin, src_reg->umin_value, dst_umin) ||
             check_add_overflow(*dst_umax, src_reg->umax_value, dst_umax)) {
                 *dst_umin = 0;
                 *dst_umax = U64_MAX;
         }
 }
 
 static void scalar32_min_max_sub(struct bpf_reg_state *dst_reg,
                                  struct bpf_reg_state *src_reg)
 {
         s32 *dst_smin = &dst_reg->s32_min_value;
         s32 *dst_smax = &dst_reg->s32_max_value;
         u32 umin_val = src_reg->u32_min_value;
         u32 umax_val = src_reg->u32_max_value;
 
         if (check_sub_overflow(*dst_smin, src_reg->s32_max_value, dst_smin) ||
             check_sub_overflow(*dst_smax, src_reg->s32_min_value, dst_smax)) {
                 /* Overflow possible, we know nothing */
                 *dst_smin = S32_MIN;
                 *dst_smax = S32_MAX;
         }
         if (dst_reg->u32_min_value < umax_val) {
                 /* Overflow possible, we know nothing */
                 dst_reg->u32_min_value = 0;
                 dst_reg->u32_max_value = U32_MAX;
         } else {
                 /* Cannot overflow (as long as bounds are consistent) */
                 dst_reg->u32_min_value -= umax_val;
                 dst_reg->u32_max_value -= umin_val;
         }
 }
 
 static void scalar_min_max_sub(struct bpf_reg_state *dst_reg,
                                struct bpf_reg_state *src_reg)
 {
         s64 *dst_smin = &dst_reg->smin_value;
         s64 *dst_smax = &dst_reg->smax_value;
         u64 umin_val = src_reg->umin_value;
         u64 umax_val = src_reg->umax_value;
 
         if (check_sub_overflow(*dst_smin, src_reg->smax_value, dst_smin) ||
             check_sub_overflow(*dst_smax, src_reg->smin_value, dst_smax)) {
                 /* Overflow possible, we know nothing */
                 *dst_smin = S64_MIN;
                 *dst_smax = S64_MAX;
         }
         if (dst_reg->umin_value < umax_val) {
                 /* Overflow possible, we know nothing */
                 dst_reg->umin_value = 0;
                 dst_reg->umax_value = U64_MAX;
         } else {
                 /* Cannot overflow (as long as bounds are consistent) */
                 dst_reg->umin_value -= umax_val;
                 dst_reg->umax_value -= umin_val;
         }
 }
 
 static void scalar32_min_max_mul(struct bpf_reg_state *dst_reg,
                                  struct bpf_reg_state *src_reg)
 {
         s32 smin_val = src_reg->s32_min_value;
         u32 umin_val = src_reg->u32_min_value;
         u32 umax_val = src_reg->u32_max_value;
 
         if (smin_val < 0 || dst_reg->s32_min_value < 0) {
                 /* Ain't nobody got time to multiply that sign */
                 __mark_reg32_unbounded(dst_reg);
                 return;
         }
         /* Both values are positive, so we can work with unsigned and
          * copy the result to signed (unless it exceeds S32_MAX).
          */
         if (umax_val > U16_MAX || dst_reg->u32_max_value > U16_MAX) {
                 /* Potential overflow, we know nothing */
                 __mark_reg32_unbounded(dst_reg);
                 return;
         }
         dst_reg->u32_min_value *= umin_val;
         dst_reg->u32_max_value *= umax_val;
         if (dst_reg->u32_max_value > S32_MAX) {
                 /* Overflow possible, we know nothing */
                 dst_reg->s32_min_value = S32_MIN;
                 dst_reg->s32_max_value = S32_MAX;
         } else {
                 dst_reg->s32_min_value = dst_reg->u32_min_value;
                 dst_reg->s32_max_value = dst_reg->u32_max_value;
         }
 }
 
 static void scalar_min_max_mul(struct bpf_reg_state *dst_reg,
                                struct bpf_reg_state *src_reg)
 {
         s64 smin_val = src_reg->smin_value;
         u64 umin_val = src_reg->umin_value;
         u64 umax_val = src_reg->umax_value;
 
         if (smin_val < 0 || dst_reg->smin_value < 0) {
                 /* Ain't nobody got time to multiply that sign */
                 __mark_reg64_unbounded(dst_reg);
                 return;
         }
         /* Both values are positive, so we can work with unsigned and
          * copy the result to signed (unless it exceeds S64_MAX).
          */
         if (umax_val > U32_MAX || dst_reg->umax_value > U32_MAX) {
                 /* Potential overflow, we know nothing */
                 __mark_reg64_unbounded(dst_reg);
                 return;
         }
         dst_reg->umin_value *= umin_val;
         dst_reg->umax_value *= umax_val;
         if (dst_reg->umax_value > S64_MAX) {
                 /* Overflow possible, we know nothing */
                 dst_reg->smin_value = S64_MIN;
                 dst_reg->smax_value = S64_MAX;
         } else {
                 dst_reg->smin_value = dst_reg->umin_value;
                 dst_reg->smax_value = dst_reg->umax_value;
         }
 }
 
 static void scalar32_min_max_and(struct bpf_reg_state *dst_reg,
                                  struct bpf_reg_state *src_reg)
 {
         bool src_known = tnum_subreg_is_const(src_reg->var_off);
         bool dst_known = tnum_subreg_is_const(dst_reg->var_off);
         struct tnum var32_off = tnum_subreg(dst_reg->var_off);
         u32 umax_val = src_reg->u32_max_value;
 
         if (src_known && dst_known) {
                 __mark_reg32_known(dst_reg, var32_off.value);
                 return;
         }
 
         /* We get our minimum from the var_off, since that's inherently
          * bitwise.  Our maximum is the minimum of the operands' maxima.
          */
         dst_reg->u32_min_value = var32_off.value;
         dst_reg->u32_max_value = min(dst_reg->u32_max_value, umax_val);
 
         /* Safe to set s32 bounds by casting u32 result into s32 when u32
          * doesn't cross sign boundary. Otherwise set s32 bounds to unbounded.
          */
         if ((s32)dst_reg->u32_min_value <= (s32)dst_reg->u32_max_value) {
                 dst_reg->s32_min_value = dst_reg->u32_min_value;
                 dst_reg->s32_max_value = dst_reg->u32_max_value;
         } else {
                 dst_reg->s32_min_value = S32_MIN;
                 dst_reg->s32_max_value = S32_MAX;
         }
 }
 
 static void scalar_min_max_and(struct bpf_reg_state *dst_reg,
                                struct bpf_reg_state *src_reg)
 {
         bool src_known = tnum_is_const(src_reg->var_off);
         bool dst_known = tnum_is_const(dst_reg->var_off);
         u64 umax_val = src_reg->umax_value;
 
         if (src_known && dst_known) {
                 __mark_reg_known(dst_reg, dst_reg->var_off.value);
                 return;
         }
 
         /* We get our minimum from the var_off, since that's inherently
          * bitwise.  Our maximum is the minimum of the operands' maxima.
          */
         dst_reg->umin_value = dst_reg->var_off.value;
         dst_reg->umax_value = min(dst_reg->umax_value, umax_val);
 
         /* Safe to set s64 bounds by casting u64 result into s64 when u64
          * doesn't cross sign boundary. Otherwise set s64 bounds to unbounded.
          */
         if ((s64)dst_reg->umin_value <= (s64)dst_reg->umax_value) {
                 dst_reg->smin_value = dst_reg->umin_value;
                 dst_reg->smax_value = dst_reg->umax_value;
         } else {
                 dst_reg->smin_value = S64_MIN;
                 dst_reg->smax_value = S64_MAX;
         }
         /* We may learn something more from the var_off */
         __update_reg_bounds(dst_reg);
 }
 
 static void scalar32_min_max_or(struct bpf_reg_state *dst_reg,
                                 struct bpf_reg_state *src_reg)
 {
         bool src_known = tnum_subreg_is_const(src_reg->var_off);
         bool dst_known = tnum_subreg_is_const(dst_reg->var_off);
         struct tnum var32_off = tnum_subreg(dst_reg->var_off);
         u32 umin_val = src_reg->u32_min_value;
 
         if (src_known && dst_known) {
                 __mark_reg32_known(dst_reg, var32_off.value);
                 return;
         }
 
         /* We get our maximum from the var_off, and our minimum is the
          * maximum of the operands' minima
          */
         dst_reg->u32_min_value = max(dst_reg->u32_min_value, umin_val);
         dst_reg->u32_max_value = var32_off.value | var32_off.mask;
 
         /* Safe to set s32 bounds by casting u32 result into s32 when u32
          * doesn't cross sign boundary. Otherwise set s32 bounds to unbounded.
          */
         if ((s32)dst_reg->u32_min_value <= (s32)dst_reg->u32_max_value) {
                 dst_reg->s32_min_value = dst_reg->u32_min_value;
                 dst_reg->s32_max_value = dst_reg->u32_max_value;
         } else {
                 dst_reg->s32_min_value = S32_MIN;
                 dst_reg->s32_max_value = S32_MAX;
         }
 }
 
 static void scalar_min_max_or(struct bpf_reg_state *dst_reg,
                               struct bpf_reg_state *src_reg)
 {
         bool src_known = tnum_is_const(src_reg->var_off);
         bool dst_known = tnum_is_const(dst_reg->var_off);
         u64 umin_val = src_reg->umin_value;
 
         if (src_known && dst_known) {
                 __mark_reg_known(dst_reg, dst_reg->var_off.value);
                 return;
         }
 
         /* We get our maximum from the var_off, and our minimum is the
          * maximum of the operands' minima
          */
         dst_reg->umin_value = max(dst_reg->umin_value, umin_val);
         dst_reg->umax_value = dst_reg->var_off.value | dst_reg->var_off.mask;
 
         /* Safe to set s64 bounds by casting u64 result into s64 when u64
          * doesn't cross sign boundary. Otherwise set s64 bounds to unbounded.
          */
         if ((s64)dst_reg->umin_value <= (s64)dst_reg->umax_value) {
                 dst_reg->smin_value = dst_reg->umin_value;
                 dst_reg->smax_value = dst_reg->umax_value;
         } else {
                 dst_reg->smin_value = S64_MIN;
                 dst_reg->smax_value = S64_MAX;
         }
         /* We may learn something more from the var_off */
         __update_reg_bounds(dst_reg);
 }
 
 static void scalar32_min_max_xor(struct bpf_reg_state *dst_reg,
                                  struct bpf_reg_state *src_reg)
 {
         bool src_known = tnum_subreg_is_const(src_reg->var_off);
         bool dst_known = tnum_subreg_is_const(dst_reg->var_off);
         struct tnum var32_off = tnum_subreg(dst_reg->var_off);
 
         if (src_known && dst_known) {
                 __mark_reg32_known(dst_reg, var32_off.value);
                 return;
         }
 
         /* We get both minimum and maximum from the var32_off. */
         dst_reg->u32_min_value = var32_off.value;
         dst_reg->u32_max_value = var32_off.value | var32_off.mask;
 
         /* Safe to set s32 bounds by casting u32 result into s32 when u32
          * doesn't cross sign boundary. Otherwise set s32 bounds to unbounded.
          */
         if ((s32)dst_reg->u32_min_value <= (s32)dst_reg->u32_max_value) {
                 dst_reg->s32_min_value = dst_reg->u32_min_value;
                 dst_reg->s32_max_value = dst_reg->u32_max_value;
         } else {
                 dst_reg->s32_min_value = S32_MIN;
                 dst_reg->s32_max_value = S32_MAX;
         }
 }
 
 static void scalar_min_max_xor(struct bpf_reg_state *dst_reg,
                                struct bpf_reg_state *src_reg)
 {
         bool src_known = tnum_is_const(src_reg->var_off);
         bool dst_known = tnum_is_const(dst_reg->var_off);
 
         if (src_known && dst_known) {
                 /* dst_reg->var_off.value has been updated earlier */
                 __mark_reg_known(dst_reg, dst_reg->var_off.value);
                 return;
         }
 
         /* We get both minimum and maximum from the var_off. */
         dst_reg->umin_value = dst_reg->var_off.value;
         dst_reg->umax_value = dst_reg->var_off.value | dst_reg->var_off.mask;
 
         /* Safe to set s64 bounds by casting u64 result into s64 when u64
          * doesn't cross sign boundary. Otherwise set s64 bounds to unbounded.
          */
         if ((s64)dst_reg->umin_value <= (s64)dst_reg->umax_value) {
                 dst_reg->smin_value = dst_reg->umin_value;
                 dst_reg->smax_value = dst_reg->umax_value;
         } else {
                 dst_reg->smin_value = S64_MIN;
                 dst_reg->smax_value = S64_MAX;
         }
 
         __update_reg_bounds(dst_reg);
 }
 
 static void __scalar32_min_max_lsh(struct bpf_reg_state *dst_reg,
                                    u64 umin_val, u64 umax_val)
 {
         /* We lose all sign bit information (except what we can pick
          * up from var_off)
          */
         dst_reg->s32_min_value = S32_MIN;
         dst_reg->s32_max_value = S32_MAX;
         /* If we might shift our top bit out, then we know nothing */
         if (umax_val > 31 || dst_reg->u32_max_value > 1ULL << (31 - umax_val)) {
                 dst_reg->u32_min_value = 0;
                 dst_reg->u32_max_value = U32_MAX;
         } else {
                 dst_reg->u32_min_value <<= umin_val;
                 dst_reg->u32_max_value <<= umax_val;
         }
 }
 
 static void scalar32_min_max_lsh(struct bpf_reg_state *dst_reg,
                                  struct bpf_reg_state *src_reg)
 {
         u32 umax_val = src_reg->u32_max_value;
         u32 umin_val = src_reg->u32_min_value;
         /* u32 alu operation will zext upper bits */
         struct tnum subreg = tnum_subreg(dst_reg->var_off);
 
         __scalar32_min_max_lsh(dst_reg, umin_val, umax_val);
         dst_reg->var_off = tnum_subreg(tnum_lshift(subreg, umin_val));
         /* Not required but being careful mark reg64 bounds as unknown so
          * that we are forced to pick them up from tnum and zext later and
          * if some path skips this step we are still safe.
          */
         __mark_reg64_unbounded(dst_reg);
         __update_reg32_bounds(dst_reg);
 }
 
 static void __scalar64_min_max_lsh(struct bpf_reg_state *dst_reg,
                                    u64 umin_val, u64 umax_val)
 {
         /* Special case <<32 because it is a common compiler pattern to sign
          * extend subreg by doing <<32 s>>32. In this case if 32bit bounds are
          * positive we know this shift will also be positive so we can track
          * bounds correctly. Otherwise we lose all sign bit information except
          * what we can pick up from var_off. Perhaps we can generalize this
          * later to shifts of any length.
          */
         if (umin_val == 32 && umax_val == 32 && dst_reg->s32_max_value >= 0)
                 dst_reg->smax_value = (s64)dst_reg->s32_max_value << 32;
         else
                 dst_reg->smax_value = S64_MAX;
 
         if (umin_val == 32 && umax_val == 32 && dst_reg->s32_min_value >= 0)
                 dst_reg->smin_value = (s64)dst_reg->s32_min_value << 32;
         else
                 dst_reg->smin_value = S64_MIN;
 
         /* If we might shift our top bit out, then we know nothing */
         if (dst_reg->umax_value > 1ULL << (63 - umax_val)) {
                 dst_reg->umin_value = 0;
                 dst_reg->umax_value = U64_MAX;
         } else {
                 dst_reg->umin_value <<= umin_val;
                 dst_reg->umax_value <<= umax_val;
         }
 }
 
 static void scalar_min_max_lsh(struct bpf_reg_state *dst_reg,
                                struct bpf_reg_state *src_reg)
 {
         u64 umax_val = src_reg->umax_value;
         u64 umin_val = src_reg->umin_value;
 
         /* scalar64 calc uses 32bit unshifted bounds so must be called first */
         __scalar64_min_max_lsh(dst_reg, umin_val, umax_val);
         __scalar32_min_max_lsh(dst_reg, umin_val, umax_val);
 
         dst_reg->var_off = tnum_lshift(dst_reg->var_off, umin_val);
         /* We may learn something more from the var_off */
         __update_reg_bounds(dst_reg);
 }
 
 static void scalar32_min_max_rsh(struct bpf_reg_state *dst_reg,
                                  struct bpf_reg_state *src_reg)
 {
         struct tnum subreg = tnum_subreg(dst_reg->var_off);
         u32 umax_val = src_reg->u32_max_value;
         u32 umin_val = src_reg->u32_min_value;
 
         /* BPF_RSH is an unsigned shift.  If the value in dst_reg might
          * be negative, then either:
          * 1) src_reg might be zero, so the sign bit of the result is
          *    unknown, so we lose our signed bounds
          * 2) it's known negative, thus the unsigned bounds capture the
          *    signed bounds
          * 3) the signed bounds cross zero, so they tell us nothing
          *    about the result
          * If the value in dst_reg is known nonnegative, then again the
          * unsigned bounds capture the signed bounds.
          * Thus, in all cases it suffices to blow away our signed bounds
          * and rely on inferring new ones from the unsigned bounds and
          * var_off of the result.
          */
         dst_reg->s32_min_value = S32_MIN;
         dst_reg->s32_max_value = S32_MAX;
 
         dst_reg->var_off = tnum_rshift(subreg, umin_val);
         dst_reg->u32_min_value >>= umax_val;
         dst_reg->u32_max_value >>= umin_val;
 
         __mark_reg64_unbounded(dst_reg);
         __update_reg32_bounds(dst_reg);
 }
 
 static void scalar_min_max_rsh(struct bpf_reg_state *dst_reg,
                                struct bpf_reg_state *src_reg)
 {
         u64 umax_val = src_reg->umax_value;
         u64 umin_val = src_reg->umin_value;
 
         /* BPF_RSH is an unsigned shift.  If the value in dst_reg might
          * be negative, then either:
          * 1) src_reg might be zero, so the sign bit of the result is
          *    unknown, so we lose our signed bounds
          * 2) it's known negative, thus the unsigned bounds capture the
          *    signed bounds
          * 3) the signed bounds cross zero, so they tell us nothing
          *    about the result
          * If the value in dst_reg is known nonnegative, then again the
          * unsigned bounds capture the signed bounds.
          * Thus, in all cases it suffices to blow away our signed bounds
          * and rely on inferring new ones from the unsigned bounds and
          * var_off of the result.
          */
         dst_reg->smin_value = S64_MIN;
         dst_reg->smax_value = S64_MAX;
         dst_reg->var_off = tnum_rshift(dst_reg->var_off, umin_val);
         dst_reg->umin_value >>= umax_val;
         dst_reg->umax_value >>= umin_val;
 
         /* Its not easy to operate on alu32 bounds here because it depends
          * on bits being shifted in. Take easy way out and mark unbounded
          * so we can recalculate later from tnum.
          */
         __mark_reg32_unbounded(dst_reg);
         __update_reg_bounds(dst_reg);
 }
 
 static void scalar32_min_max_arsh(struct bpf_reg_state *dst_reg,
                                   struct bpf_reg_state *src_reg)
 {
         u64 umin_val = src_reg->u32_min_value;
 
         /* Upon reaching here, src_known is true and
          * umax_val is equal to umin_val.
          */
         dst_reg->s32_min_value = (u32)(((s32)dst_reg->s32_min_value) >> umin_val);
         dst_reg->s32_max_value = (u32)(((s32)dst_reg->s32_max_value) >> umin_val);
 
         dst_reg->var_off = tnum_arshift(tnum_subreg(dst_reg->var_off), umin_val, 32);
 
         /* blow away the dst_reg umin_value/umax_value and rely on
          * dst_reg var_off to refine the result.
          */
         dst_reg->u32_min_value = 0;
         dst_reg->u32_max_value = U32_MAX;
 
         __mark_reg64_unbounded(dst_reg);
         __update_reg32_bounds(dst_reg);
 }
 
 static void scalar_min_max_arsh(struct bpf_reg_state *dst_reg,
                                 struct bpf_reg_state *src_reg)
 {
         u64 umin_val = src_reg->umin_value;
 
         /* Upon reaching here, src_known is true and umax_val is equal
          * to umin_val.
          */
         dst_reg->smin_value >>= umin_val;
         dst_reg->smax_value >>= umin_val;
 
         dst_reg->var_off = tnum_arshift(dst_reg->var_off, umin_val, 64);
 
         /* blow away the dst_reg umin_value/umax_value and rely on
          * dst_reg var_off to refine the result.
          */
         dst_reg->umin_value = 0;
         dst_reg->umax_value = U64_MAX;
 
         /* Its not easy to operate on alu32 bounds here because it depends
          * on bits being shifted in from upper 32-bits. Take easy way out
          * and mark unbounded so we can recalculate later from tnum.
          */
         __mark_reg32_unbounded(dst_reg);
         __update_reg_bounds(dst_reg);
 }
 
 static bool is_safe_to_compute_dst_reg_range(struct bpf_insn *insn,
                                              const struct bpf_reg_state *src_reg)
 {
         bool src_is_const = false;
         u64 insn_bitness = (BPF_CLASS(insn->code) == BPF_ALU64) ? 64 : 32;
 
         if (insn_bitness == 32) {
                 if (tnum_subreg_is_const(src_reg->var_off)
                     && src_reg->s32_min_value == src_reg->s32_max_value
                     && src_reg->u32_min_value == src_reg->u32_max_value)
                         src_is_const = true;
         } else {
                 if (tnum_is_const(src_reg->var_off)
                     && src_reg->smin_value == src_reg->smax_value
                     && src_reg->umin_value == src_reg->umax_value)
                         src_is_const = true;
         }
 
         switch (BPF_OP(insn->code)) {
         case BPF_ADD:
         case BPF_SUB:
         case BPF_AND:
         case BPF_XOR:
         case BPF_OR:
         case BPF_MUL:
                 return true;
 
         /* Shift operators range is only computable if shift dimension operand
          * is a constant. Shifts greater than 31 or 63 are undefined. This
          * includes shifts by a negative number.
          */
         case BPF_LSH:
         case BPF_RSH:
         case BPF_ARSH:
                 return (src_is_const && src_reg->umax_value < insn_bitness);
         default:
                 return false;
         }
 }
 
 /* WARNING: This function does calculations on 64-bit values, but the actual
  * execution may occur on 32-bit values. Therefore, things like bitshifts
  * need extra checks in the 32-bit case.
  */
 static int adjust_scalar_min_max_vals(struct bpf_verifier_env *env,
                                       struct bpf_insn *insn,
                                       struct bpf_reg_state *dst_reg,
                                       struct bpf_reg_state src_reg)
 {
         u8 opcode = BPF_OP(insn->code);
         bool alu32 = (BPF_CLASS(insn->code) != BPF_ALU64);
         int ret;
 
         if (!is_safe_to_compute_dst_reg_range(insn, &src_reg)) {
                 __mark_reg_unknown(env, dst_reg);
                 return 0;
         }
 
         if (sanitize_needed(opcode)) {
                 ret = sanitize_val_alu(env, insn);
                 if (ret < 0)
                         return sanitize_err(env, insn, ret, NULL, NULL);
         }
 
         /* Calculate sign/unsigned bounds and tnum for alu32 and alu64 bit ops.
          * There are two classes of instructions: The first class we track both
          * alu32 and alu64 sign/unsigned bounds independently this provides the
          * greatest amount of precision when alu operations are mixed with jmp32
          * operations. These operations are BPF_ADD, BPF_SUB, BPF_MUL, BPF_ADD,
          * and BPF_OR. This is possible because these ops have fairly easy to
          * understand and calculate behavior in both 32-bit and 64-bit alu ops.
          * See alu32 verifier tests for examples. The second class of
          * operations, BPF_LSH, BPF_RSH, and BPF_ARSH, however are not so easy
          * with regards to tracking sign/unsigned bounds because the bits may
          * cross subreg boundaries in the alu64 case. When this happens we mark
          * the reg unbounded in the subreg bound space and use the resulting
          * tnum to calculate an approximation of the sign/unsigned bounds.
          */
         switch (opcode) {
         case BPF_ADD:
                 scalar32_min_max_add(dst_reg, &src_reg);
                 scalar_min_max_add(dst_reg, &src_reg);
                 dst_reg->var_off = tnum_add(dst_reg->var_off, src_reg.var_off);
                 break;
         case BPF_SUB:
                 scalar32_min_max_sub(dst_reg, &src_reg);
                 scalar_min_max_sub(dst_reg, &src_reg);
                 dst_reg->var_off = tnum_sub(dst_reg->var_off, src_reg.var_off);
                 break;
         case BPF_MUL:
                 dst_reg->var_off = tnum_mul(dst_reg->var_off, src_reg.var_off);
                 scalar32_min_max_mul(dst_reg, &src_reg);
                 scalar_min_max_mul(dst_reg, &src_reg);
                 break;
         case BPF_AND:
                 dst_reg->var_off = tnum_and(dst_reg->var_off, src_reg.var_off);
                 scalar32_min_max_and(dst_reg, &src_reg);
                 scalar_min_max_and(dst_reg, &src_reg);
                 break;
         case BPF_OR:
                 dst_reg->var_off = tnum_or(dst_reg->var_off, src_reg.var_off);
                 scalar32_min_max_or(dst_reg, &src_reg);
                 scalar_min_max_or(dst_reg, &src_reg);
                 break;
         case BPF_XOR:
                 dst_reg->var_off = tnum_xor(dst_reg->var_off, src_reg.var_off);
                 scalar32_min_max_xor(dst_reg, &src_reg);
                 scalar_min_max_xor(dst_reg, &src_reg);
                 break;
         case BPF_LSH:
                 if (alu32)
                         scalar32_min_max_lsh(dst_reg, &src_reg);
                 else
                         scalar_min_max_lsh(dst_reg, &src_reg);
                 break;
         case BPF_RSH:
                 if (alu32)
                         scalar32_min_max_rsh(dst_reg, &src_reg);
                 else
                         scalar_min_max_rsh(dst_reg, &src_reg);
                 break;
         case BPF_ARSH:
                 if (alu32)
                         scalar32_min_max_arsh(dst_reg, &src_reg);
                 else
                         scalar_min_max_arsh(dst_reg, &src_reg);
                 break;
         default:
                 break;
         }
 
         /* ALU32 ops are zero extended into 64bit register */
         if (alu32)
                 zext_32_to_64(dst_reg);
         reg_bounds_sync(dst_reg);
         return 0;
 }
 
 /* Handles ALU ops other than BPF_END, BPF_NEG and BPF_MOV: computes new min/max
  * and var_off.
  */
 static int adjust_reg_min_max_vals(struct bpf_verifier_env *env,
                                    struct bpf_insn *insn)
 {
         struct bpf_verifier_state *vstate = env->cur_state;
         struct bpf_func_state *state = vstate->frame[vstate->curframe];
         struct bpf_reg_state *regs = state->regs, *dst_reg, *src_reg;
         struct bpf_reg_state *ptr_reg = NULL, off_reg = {0};
         bool alu32 = (BPF_CLASS(insn->code) != BPF_ALU64);
         u8 opcode = BPF_OP(insn->code);
         int err;
 
         dst_reg = &regs[insn->dst_reg];
         src_reg = NULL;
 
         if (dst_reg->type == PTR_TO_ARENA) {
                 struct bpf_insn_aux_data *aux = cur_aux(env);
 
                 if (BPF_CLASS(insn->code) == BPF_ALU64)
                         /*
                          * 32-bit operations zero upper bits automatically.
                          * 64-bit operations need to be converted to 32.
                          */
                         aux->needs_zext = true;
 
                 /* Any arithmetic operations are allowed on arena pointers */
                 return 0;
         }
 
         if (dst_reg->type != SCALAR_VALUE)
                 ptr_reg = dst_reg;
 
         if (BPF_SRC(insn->code) == BPF_X) {
                 src_reg = &regs[insn->src_reg];
                 if (src_reg->type != SCALAR_VALUE) {
                         if (dst_reg->type != SCALAR_VALUE) {
                                 /* Combining two pointers by any ALU op yields
                                  * an arbitrary scalar. Disallow all math except
                                  * pointer subtraction
                                  */
                                 if (opcode == BPF_SUB && env->allow_ptr_leaks) {
                                         mark_reg_unknown(env, regs, insn->dst_reg);
                                         return 0;
                                 }
                                 verbose(env, "R%d pointer %s pointer prohibited\n",
                                         insn->dst_reg,
                                         bpf_alu_string[opcode >> 4]);
                                 return -EACCES;
                         } else {
                                 /* scalar += pointer
                                  * This is legal, but we have to reverse our
                                  * src/dest handling in computing the range
                                  */
                                 err = mark_chain_precision(env, insn->dst_reg);
                                 if (err)
                                         return err;
                                 return adjust_ptr_min_max_vals(env, insn,
                                                                src_reg, dst_reg);
                         }
                 } else if (ptr_reg) {
                         /* pointer += scalar */
                         err = mark_chain_precision(env, insn->src_reg);
                         if (err)
                                 return err;
                         return adjust_ptr_min_max_vals(env, insn,
                                                        dst_reg, src_reg);
                 } else if (dst_reg->precise) {
                         /* if dst_reg is precise, src_reg should be precise as well */
                         err = mark_chain_precision(env, insn->src_reg);
                         if (err)
                                 return err;
                 }
         } else {
                 /* Pretend the src is a reg with a known value, since we only
                  * need to be able to read from this state.
                  */
                 off_reg.type = SCALAR_VALUE;
                 __mark_reg_known(&off_reg, insn->imm);
                 src_reg = &off_reg;
                 if (ptr_reg) /* pointer += K */
                         return adjust_ptr_min_max_vals(env, insn,
                                                        ptr_reg, src_reg);
         }
 
         /* Got here implies adding two SCALAR_VALUEs */
         if (WARN_ON_ONCE(ptr_reg)) {
                 print_verifier_state(env, state, true);
                 verbose(env, "verifier internal error: unexpected ptr_reg\n");
                 return -EINVAL;
         }
         if (WARN_ON(!src_reg)) {
                 print_verifier_state(env, state, true);
                 verbose(env, "verifier internal error: no src_reg\n");
                 return -EINVAL;
         }
         err = adjust_scalar_min_max_vals(env, insn, dst_reg, *src_reg);
         if (err)
                 return err;
         /*
          * Compilers can generate the code
          * r1 = r2
          * r1 += 0x1
          * if r2 < 1000 goto ...
          * use r1 in memory access
          * So remember constant delta between r2 and r1 and update r1 after
          * 'if' condition.
          */
         if (env->bpf_capable && BPF_OP(insn->code) == BPF_ADD &&
             dst_reg->id && is_reg_const(src_reg, alu32)) {
                 u64 val = reg_const_value(src_reg, alu32);
 
                 if ((dst_reg->id & BPF_ADD_CONST) ||
                     /* prevent overflow in find_equal_scalars() later */
                     val > (u32)S32_MAX) {
                         /*
                          * If the register already went through rX += val
                          * we cannot accumulate another val into rx->off.
                          */
                         dst_reg->off = 0;
                         dst_reg->id = 0;
                 } else {
                         dst_reg->id |= BPF_ADD_CONST;
                         dst_reg->off = val;
                 }
         } else {
                 /*
                  * Make sure ID is cleared otherwise dst_reg min/max could be
                  * incorrectly propagated into other registers by find_equal_scalars()
                  */
                 dst_reg->id = 0;
         }
         return 0;
 }
 
 /* check validity of 32-bit and 64-bit arithmetic operations */
 static int check_alu_op(struct bpf_verifier_env *env, struct bpf_insn *insn)
 {
         struct bpf_reg_state *regs = cur_regs(env);
         u8 opcode = BPF_OP(insn->code);
         int err;
 
         if (opcode == BPF_END || opcode == BPF_NEG) {
                 if (opcode == BPF_NEG) {
                         if (BPF_SRC(insn->code) != BPF_K ||
                             insn->src_reg != BPF_REG_0 ||
                             insn->off != 0 || insn->imm != 0) {
                                 verbose(env, "BPF_NEG uses reserved fields\n");
                                 return -EINVAL;
                         }
                 } else {
                         if (insn->src_reg != BPF_REG_0 || insn->off != 0 ||
                             (insn->imm != 16 && insn->imm != 32 && insn->imm != 64) ||
                             (BPF_CLASS(insn->code) == BPF_ALU64 &&
                              BPF_SRC(insn->code) != BPF_TO_LE)) {
                                 verbose(env, "BPF_END uses reserved fields\n");
                                 return -EINVAL;
                         }
                 }
 
                 /* check src operand */
                 err = check_reg_arg(env, insn->dst_reg, SRC_OP);
                 if (err)
                         return err;
 
                 if (is_pointer_value(env, insn->dst_reg)) {
                         verbose(env, "R%d pointer arithmetic prohibited\n",
                                 insn->dst_reg);
                         return -EACCES;
                 }
 
                 /* check dest operand */
                 err = check_reg_arg(env, insn->dst_reg, DST_OP);
                 if (err)
                         return err;
 
         } else if (opcode == BPF_MOV) {
 
                 if (BPF_SRC(insn->code) == BPF_X) {
                         if (BPF_CLASS(insn->code) == BPF_ALU) {
                                 if ((insn->off != 0 && insn->off != 8 && insn->off != 16) ||
                                     insn->imm) {
                                         verbose(env, "BPF_MOV uses reserved fields\n");
                                         return -EINVAL;
                                 }
                         } else if (insn->off == BPF_ADDR_SPACE_CAST) {
                                 if (insn->imm != 1 && insn->imm != 1u << 16) {
                                         verbose(env, "addr_space_cast insn can only convert between address space 1 and 0\n");
                                         return -EINVAL;
                                 }
                                 if (!env->prog->aux->arena) {
                                         verbose(env, "addr_space_cast insn can only be used in a program that has an associated arena\n");
                                         return -EINVAL;
                                 }
                         } else {
                                 if ((insn->off != 0 && insn->off != 8 && insn->off != 16 &&
                                      insn->off != 32) || insn->imm) {
                                         verbose(env, "BPF_MOV uses reserved fields\n");
                                         return -EINVAL;
                                 }
                         }
 
                         /* check src operand */
                         err = check_reg_arg(env, insn->src_reg, SRC_OP);
                         if (err)
                                 return err;
                 } else {
                         if (insn->src_reg != BPF_REG_0 || insn->off != 0) {
                                 verbose(env, "BPF_MOV uses reserved fields\n");
                                 return -EINVAL;
                         }
                 }
 
                 /* check dest operand, mark as required later */
                 err = check_reg_arg(env, insn->dst_reg, DST_OP_NO_MARK);
                 if (err)
                         return err;
 
                 if (BPF_SRC(insn->code) == BPF_X) {
                         struct bpf_reg_state *src_reg = regs + insn->src_reg;
                         struct bpf_reg_state *dst_reg = regs + insn->dst_reg;
 
                         if (BPF_CLASS(insn->code) == BPF_ALU64) {
                                 if (insn->imm) {
                                         /* off == BPF_ADDR_SPACE_CAST */
                                         mark_reg_unknown(env, regs, insn->dst_reg);
                                         if (insn->imm == 1) { /* cast from as(1) to as(0) */
                                                 dst_reg->type = PTR_TO_ARENA;
                                                 /* PTR_TO_ARENA is 32-bit */
                                                 dst_reg->subreg_def = env->insn_idx + 1;
                                         }
                                 } else if (insn->off == 0) {
                                         /* case: R1 = R2
                                          * copy register state to dest reg
                                          */
                                         assign_scalar_id_before_mov(env, src_reg);
                                         copy_register_state(dst_reg, src_reg);
                                         dst_reg->live |= REG_LIVE_WRITTEN;
                                         dst_reg->subreg_def = DEF_NOT_SUBREG;
                                 } else {
                                         /* case: R1 = (s8, s16 s32)R2 */
                                         if (is_pointer_value(env, insn->src_reg)) {
                                                 verbose(env,
                                                         "R%d sign-extension part of pointer\n",
                                                         insn->src_reg);
                                                 return -EACCES;
                                         } else if (src_reg->type == SCALAR_VALUE) {
                                                 bool no_sext;
 
                                                 no_sext = src_reg->umax_value < (1ULL << (insn->off - 1));
                                                 if (no_sext)
                                                         assign_scalar_id_before_mov(env, src_reg);
                                                 copy_register_state(dst_reg, src_reg);
                                                 if (!no_sext)
                                                         dst_reg->id = 0;
                                                 coerce_reg_to_size_sx(dst_reg, insn->off >> 3);
                                                 dst_reg->live |= REG_LIVE_WRITTEN;
                                                 dst_reg->subreg_def = DEF_NOT_SUBREG;
                                         } else {
                                                 mark_reg_unknown(env, regs, insn->dst_reg);
                                         }
                                 }
                         } else {
                                 /* R1 = (u32) R2 */
                                 if (is_pointer_value(env, insn->src_reg)) {
                                         verbose(env,
                                                 "R%d partial copy of pointer\n",
                                                 insn->src_reg);
                                         return -EACCES;
                                 } else if (src_reg->type == SCALAR_VALUE) {
                                         if (insn->off == 0) {
                                                 bool is_src_reg_u32 = get_reg_width(src_reg) <= 32;
 
                                                 if (is_src_reg_u32)
                                                         assign_scalar_id_before_mov(env, src_reg);
                                                 copy_register_state(dst_reg, src_reg);
                                                 /* Make sure ID is cleared if src_reg is not in u32
                                                  * range otherwise dst_reg min/max could be incorrectly
                                                  * propagated into src_reg by find_equal_scalars()
                                                  */
                                                 if (!is_src_reg_u32)
                                                         dst_reg->id = 0;
                                                 dst_reg->live |= REG_LIVE_WRITTEN;
                                                 dst_reg->subreg_def = env->insn_idx + 1;
                                         } else {
                                                 /* case: W1 = (s8, s16)W2 */
                                                 bool no_sext = src_reg->umax_value < (1ULL << (insn->off - 1));
 
                                                 if (no_sext)
                                                         assign_scalar_id_before_mov(env, src_reg);
                                                 copy_register_state(dst_reg, src_reg);
                                                 if (!no_sext)
                                                         dst_reg->id = 0;
                                                 dst_reg->live |= REG_LIVE_WRITTEN;
                                                 dst_reg->subreg_def = env->insn_idx + 1;
                                                 coerce_subreg_to_size_sx(dst_reg, insn->off >> 3);
                                         }
                                 } else {
                                         mark_reg_unknown(env, regs,
                                                          insn->dst_reg);
                                 }
                                 zext_32_to_64(dst_reg);
                                 reg_bounds_sync(dst_reg);
                         }
                 } else {
                         /* case: R = imm
                          * remember the value we stored into this reg
                          */
                         /* clear any state __mark_reg_known doesn't set */
                         mark_reg_unknown(env, regs, insn->dst_reg);
                         regs[insn->dst_reg].type = SCALAR_VALUE;
                         if (BPF_CLASS(insn->code) == BPF_ALU64) {
                                 __mark_reg_known(regs + insn->dst_reg,
                                                  insn->imm);
                         } else {
                                 __mark_reg_known(regs + insn->dst_reg,
                                                  (u32)insn->imm);
                         }
                 }
 
         } else if (opcode > BPF_END) {
                 verbose(env, "invalid BPF_ALU opcode %x\n", opcode);
                 return -EINVAL;
 
         } else {        /* all other ALU ops: and, sub, xor, add, ... */
 
                 if (BPF_SRC(insn->code) == BPF_X) {
                         if (insn->imm != 0 || insn->off > 1 ||
                             (insn->off == 1 && opcode != BPF_MOD && opcode != BPF_DIV)) {
                                 verbose(env, "BPF_ALU uses reserved fields\n");
                                 return -EINVAL;
                         }
                         /* check src1 operand */
                         err = check_reg_arg(env, insn->src_reg, SRC_OP);
                         if (err)
                                 return err;
                 } else {
                         if (insn->src_reg != BPF_REG_0 || insn->off > 1 ||
                             (insn->off == 1 && opcode != BPF_MOD && opcode != BPF_DIV)) {
                                 verbose(env, "BPF_ALU uses reserved fields\n");
                                 return -EINVAL;
                         }
                 }
 
                 /* check src2 operand */
                 err = check_reg_arg(env, insn->dst_reg, SRC_OP);
                 if (err)
                         return err;
 
                 if ((opcode == BPF_MOD || opcode == BPF_DIV) &&
                     BPF_SRC(insn->code) == BPF_K && insn->imm == 0) {
                         verbose(env, "div by zero\n");
                         return -EINVAL;
                 }
 
                 if ((opcode == BPF_LSH || opcode == BPF_RSH ||
                      opcode == BPF_ARSH) && BPF_SRC(insn->code) == BPF_K) {
                         int size = BPF_CLASS(insn->code) == BPF_ALU64 ? 64 : 32;
 
                         if (insn->imm < 0 || insn->imm >= size) {
                                 verbose(env, "invalid shift %d\n", insn->imm);
                                 return -EINVAL;
                         }
                 }
 
                 /* check dest operand */
                 err = check_reg_arg(env, insn->dst_reg, DST_OP_NO_MARK);
                 err = err ?: adjust_reg_min_max_vals(env, insn);
                 if (err)
                         return err;
         }
 
         return reg_bounds_sanity_check(env, &regs[insn->dst_reg], "alu");
 }
 
 static void find_good_pkt_pointers(struct bpf_verifier_state *vstate,
                                    struct bpf_reg_state *dst_reg,
                                    enum bpf_reg_type type,
                                    bool range_right_open)
 {
         struct bpf_func_state *state;
         struct bpf_reg_state *reg;
         int new_range;
 
         if (dst_reg->off < 0 ||
             (dst_reg->off == 0 && range_right_open))
                 /* This doesn't give us any range */
                 return;
 
         if (dst_reg->umax_value > MAX_PACKET_OFF ||
             dst_reg->umax_value + dst_reg->off > MAX_PACKET_OFF)
                 /* Risk of overflow.  For instance, ptr + (1<<63) may be less
                  * than pkt_end, but that's because it's also less than pkt.
                  */
                 return;
 
         new_range = dst_reg->off;
         if (range_right_open)
                 new_range++;
 
         /* Examples for register markings:
          *
          * pkt_data in dst register:
          *
          *   r2 = r3;
          *   r2 += 8;
          *   if (r2 > pkt_end) goto <handle exception>
          *   <access okay>
          *
          *   r2 = r3;
          *   r2 += 8;
          *   if (r2 < pkt_end) goto <access okay>
          *   <handle exception>
          *
          *   Where:
          *     r2 == dst_reg, pkt_end == src_reg
          *     r2=pkt(id=n,off=8,r=0)
          *     r3=pkt(id=n,off=0,r=0)
          *
          * pkt_data in src register:
          *
          *   r2 = r3;
          *   r2 += 8;
          *   if (pkt_end >= r2) goto <access okay>
          *   <handle exception>
          *
          *   r2 = r3;
          *   r2 += 8;
          *   if (pkt_end <= r2) goto <handle exception>
          *   <access okay>
          *
          *   Where:
          *     pkt_end == dst_reg, r2 == src_reg
          *     r2=pkt(id=n,off=8,r=0)
          *     r3=pkt(id=n,off=0,r=0)
          *
          * Find register r3 and mark its range as r3=pkt(id=n,off=0,r=8)
          * or r3=pkt(id=n,off=0,r=8-1), so that range of bytes [r3, r3 + 8)
          * and [r3, r3 + 8-1) respectively is safe to access depending on
          * the check.
          */
 
         /* If our ids match, then we must have the same max_value.  And we
          * don't care about the other reg's fixed offset, since if it's too big
          * the range won't allow anything.
          * dst_reg->off is known < MAX_PACKET_OFF, therefore it fits in a u16.
          */
         bpf_for_each_reg_in_vstate(vstate, state, reg, ({
                 if (reg->type == type && reg->id == dst_reg->id)
                         /* keep the maximum range already checked */
                         reg->range = max(reg->range, new_range);
         }));
 }
 
 /*
  * <reg1> <op> <reg2>, currently assuming reg2 is a constant
  */
 static int is_scalar_branch_taken(struct bpf_reg_state *reg1, struct bpf_reg_state *reg2,
                                   u8 opcode, bool is_jmp32)
 {
         struct tnum t1 = is_jmp32 ? tnum_subreg(reg1->var_off) : reg1->var_off;
         struct tnum t2 = is_jmp32 ? tnum_subreg(reg2->var_off) : reg2->var_off;
         u64 umin1 = is_jmp32 ? (u64)reg1->u32_min_value : reg1->umin_value;
         u64 umax1 = is_jmp32 ? (u64)reg1->u32_max_value : reg1->umax_value;
         s64 smin1 = is_jmp32 ? (s64)reg1->s32_min_value : reg1->smin_value;
         s64 smax1 = is_jmp32 ? (s64)reg1->s32_max_value : reg1->smax_value;
         u64 umin2 = is_jmp32 ? (u64)reg2->u32_min_value : reg2->umin_value;
         u64 umax2 = is_jmp32 ? (u64)reg2->u32_max_value : reg2->umax_value;
         s64 smin2 = is_jmp32 ? (s64)reg2->s32_min_value : reg2->smin_value;
         s64 smax2 = is_jmp32 ? (s64)reg2->s32_max_value : reg2->smax_value;
 
         switch (opcode) {
         case BPF_JEQ:
                 /* constants, umin/umax and smin/smax checks would be
                  * redundant in this case because they all should match
                  */
                 if (tnum_is_const(t1) && tnum_is_const(t2))
                         return t1.value == t2.value;
                 /* non-overlapping ranges */
                 if (umin1 > umax2 || umax1 < umin2)
                         return 0;
                 if (smin1 > smax2 || smax1 < smin2)
                         return 0;
                 if (!is_jmp32) {
                         /* if 64-bit ranges are inconclusive, see if we can
                          * utilize 32-bit subrange knowledge to eliminate
                          * branches that can't be taken a priori
                          */
                         if (reg1->u32_min_value > reg2->u32_max_value ||
                             reg1->u32_max_value < reg2->u32_min_value)
                                 return 0;
                         if (reg1->s32_min_value > reg2->s32_max_value ||
                             reg1->s32_max_value < reg2->s32_min_value)
                                 return 0;
                 }
                 break;
         case BPF_JNE:
                 /* constants, umin/umax and smin/smax checks would be
                  * redundant in this case because they all should match
                  */
                 if (tnum_is_const(t1) && tnum_is_const(t2))
                         return t1.value != t2.value;
                 /* non-overlapping ranges */
                 if (umin1 > umax2 || umax1 < umin2)
                         return 1;
                 if (smin1 > smax2 || smax1 < smin2)
                         return 1;
                 if (!is_jmp32) {
                         /* if 64-bit ranges are inconclusive, see if we can
                          * utilize 32-bit subrange knowledge to eliminate
                          * branches that can't be taken a priori
                          */
                         if (reg1->u32_min_value > reg2->u32_max_value ||
                             reg1->u32_max_value < reg2->u32_min_value)
                                 return 1;
                         if (reg1->s32_min_value > reg2->s32_max_value ||
                             reg1->s32_max_value < reg2->s32_min_value)
                                 return 1;
                 }
                 break;
         case BPF_JSET:
                 if (!is_reg_const(reg2, is_jmp32)) {
                         swap(reg1, reg2);
                         swap(t1, t2);
                 }
                 if (!is_reg_const(reg2, is_jmp32))
                         return -1;
                 if ((~t1.mask & t1.value) & t2.value)
                         return 1;
                 if (!((t1.mask | t1.value) & t2.value))
                         return 0;
                 break;
         case BPF_JGT:
                 if (umin1 > umax2)
                         return 1;
                 else if (umax1 <= umin2)
                         return 0;
                 break;
         case BPF_JSGT:
                 if (smin1 > smax2)
                         return 1;
                 else if (smax1 <= smin2)
                         return 0;
                 break;
         case BPF_JLT:
                 if (umax1 < umin2)
                         return 1;
                 else if (umin1 >= umax2)
                         return 0;
                 break;
         case BPF_JSLT:
                 if (smax1 < smin2)
                         return 1;
                 else if (smin1 >= smax2)
                         return 0;
                 break;
         case BPF_JGE:
                 if (umin1 >= umax2)
                         return 1;
                 else if (umax1 < umin2)
                         return 0;
                 break;
         case BPF_JSGE:
                 if (smin1 >= smax2)
                         return 1;
                 else if (smax1 < smin2)
                         return 0;
                 break;
         case BPF_JLE:
                 if (umax1 <= umin2)
                         return 1;
                 else if (umin1 > umax2)
                         return 0;
                 break;
         case BPF_JSLE:
                 if (smax1 <= smin2)
                         return 1;
                 else if (smin1 > smax2)
                         return 0;
                 break;
         }
 
         return -1;
 }
 
 static int flip_opcode(u32 opcode)
 {
         /* How can we transform "a <op> b" into "b <op> a"? */
         static const u8 opcode_flip[16] = {
                 /* these stay the same */
                 [BPF_JEQ  >> 4] = BPF_JEQ,
                 [BPF_JNE  >> 4] = BPF_JNE,
                 [BPF_JSET >> 4] = BPF_JSET,
                 /* these swap "lesser" and "greater" (L and G in the opcodes) */
                 [BPF_JGE  >> 4] = BPF_JLE,
                 [BPF_JGT  >> 4] = BPF_JLT,
                 [BPF_JLE  >> 4] = BPF_JGE,
                 [BPF_JLT  >> 4] = BPF_JGT,
                 [BPF_JSGE >> 4] = BPF_JSLE,
                 [BPF_JSGT >> 4] = BPF_JSLT,
                 [BPF_JSLE >> 4] = BPF_JSGE,
                 [BPF_JSLT >> 4] = BPF_JSGT
         };
         return opcode_flip[opcode >> 4];
 }
 
 static int is_pkt_ptr_branch_taken(struct bpf_reg_state *dst_reg,
                                    struct bpf_reg_state *src_reg,
                                    u8 opcode)
 {
         struct bpf_reg_state *pkt;
 
         if (src_reg->type == PTR_TO_PACKET_END) {
                 pkt = dst_reg;
         } else if (dst_reg->type == PTR_TO_PACKET_END) {
                 pkt = src_reg;
                 opcode = flip_opcode(opcode);
         } else {
                 return -1;
         }
 
         if (pkt->range >= 0)
                 return -1;
 
         switch (opcode) {
         case BPF_JLE:
                 /* pkt <= pkt_end */
                 fallthrough;
         case BPF_JGT:
                 /* pkt > pkt_end */
                 if (pkt->range == BEYOND_PKT_END)
                         /* pkt has at last one extra byte beyond pkt_end */
                         return opcode == BPF_JGT;
                 break;
         case BPF_JLT:
                 /* pkt < pkt_end */
                 fallthrough;
         case BPF_JGE:
                 /* pkt >= pkt_end */
                 if (pkt->range == BEYOND_PKT_END || pkt->range == AT_PKT_END)
                         return opcode == BPF_JGE;
                 break;
         }
         return -1;
 }
 
 /* compute branch direction of the expression "if (<reg1> opcode <reg2>) goto target;"
  * and return:
  *  1 - branch will be taken and "goto target" will be executed
  *  0 - branch will not be taken and fall-through to next insn
  * -1 - unknown. Example: "if (reg1 < 5)" is unknown when register value
  *      range [0,10]
  */
 static int is_branch_taken(struct bpf_reg_state *reg1, struct bpf_reg_state *reg2,
                            u8 opcode, bool is_jmp32)
 {
         if (reg_is_pkt_pointer_any(reg1) && reg_is_pkt_pointer_any(reg2) && !is_jmp32)
                 return is_pkt_ptr_branch_taken(reg1, reg2, opcode);
 
         if (__is_pointer_value(false, reg1) || __is_pointer_value(false, reg2)) {
                 u64 val;
 
                 /* arrange that reg2 is a scalar, and reg1 is a pointer */
                 if (!is_reg_const(reg2, is_jmp32)) {
                         opcode = flip_opcode(opcode);
                         swap(reg1, reg2);
                 }
                 /* and ensure that reg2 is a constant */
                 if (!is_reg_const(reg2, is_jmp32))
                         return -1;
 
                 if (!reg_not_null(reg1))
                         return -1;
 
                 /* If pointer is valid tests against zero will fail so we can
                  * use this to direct branch taken.
                  */
                 val = reg_const_value(reg2, is_jmp32);
                 if (val != 0)
                         return -1;
 
                 switch (opcode) {
                 case BPF_JEQ:
                         return 0;
                 case BPF_JNE:
                         return 1;
                 default:
                         return -1;
                 }
         }
 
         /* now deal with two scalars, but not necessarily constants */
         return is_scalar_branch_taken(reg1, reg2, opcode, is_jmp32);
 }
 
 /* Opcode that corresponds to a *false* branch condition.
  * E.g., if r1 < r2, then reverse (false) condition is r1 >= r2
  */
 static u8 rev_opcode(u8 opcode)
 {
         switch (opcode) {
         case BPF_JEQ:           return BPF_JNE;
         case BPF_JNE:           return BPF_JEQ;
         /* JSET doesn't have it's reverse opcode in BPF, so add
          * BPF_X flag to denote the reverse of that operation
          */
         case BPF_JSET:          return BPF_JSET | BPF_X;
         case BPF_JSET | BPF_X:  return BPF_JSET;
         case BPF_JGE:           return BPF_JLT;
         case BPF_JGT:           return BPF_JLE;
         case BPF_JLE:           return BPF_JGT;
         case BPF_JLT:           return BPF_JGE;
         case BPF_JSGE:          return BPF_JSLT;
         case BPF_JSGT:          return BPF_JSLE;
         case BPF_JSLE:          return BPF_JSGT;
         case BPF_JSLT:          return BPF_JSGE;
         default:                return 0;
         }
 }
 
 /* Refine range knowledge for <reg1> <op> <reg>2 conditional operation. */
 static void regs_refine_cond_op(struct bpf_reg_state *reg1, struct bpf_reg_state *reg2,
                                 u8 opcode, bool is_jmp32)
 {
         struct tnum t;
         u64 val;
 
         /* In case of GE/GT/SGE/JST, reuse LE/LT/SLE/SLT logic from below */
         switch (opcode) {
         case BPF_JGE:
         case BPF_JGT:
         case BPF_JSGE:
         case BPF_JSGT:
                 opcode = flip_opcode(opcode);
                 swap(reg1, reg2);
                 break;
         default:
                 break;
         }
 
         switch (opcode) {
         case BPF_JEQ:
                 if (is_jmp32) {
                         reg1->u32_min_value = max(reg1->u32_min_value, reg2->u32_min_value);
                         reg1->u32_max_value = min(reg1->u32_max_value, reg2->u32_max_value);
                         reg1->s32_min_value = max(reg1->s32_min_value, reg2->s32_min_value);
                         reg1->s32_max_value = min(reg1->s32_max_value, reg2->s32_max_value);
                         reg2->u32_min_value = reg1->u32_min_value;
                         reg2->u32_max_value = reg1->u32_max_value;
                         reg2->s32_min_value = reg1->s32_min_value;
                         reg2->s32_max_value = reg1->s32_max_value;
 
                         t = tnum_intersect(tnum_subreg(reg1->var_off), tnum_subreg(reg2->var_off));
                         reg1->var_off = tnum_with_subreg(reg1->var_off, t);
                         reg2->var_off = tnum_with_subreg(reg2->var_off, t);
                 } else {
                         reg1->umin_value = max(reg1->umin_value, reg2->umin_value);
                         reg1->umax_value = min(reg1->umax_value, reg2->umax_value);
                         reg1->smin_value = max(reg1->smin_value, reg2->smin_value);
                         reg1->smax_value = min(reg1->smax_value, reg2->smax_value);
                         reg2->umin_value = reg1->umin_value;
                         reg2->umax_value = reg1->umax_value;
                         reg2->smin_value = reg1->smin_value;
                         reg2->smax_value = reg1->smax_value;
 
                         reg1->var_off = tnum_intersect(reg1->var_off, reg2->var_off);
                         reg2->var_off = reg1->var_off;
                 }
                 break;
         case BPF_JNE:
                 if (!is_reg_const(reg2, is_jmp32))
                         swap(reg1, reg2);
                 if (!is_reg_const(reg2, is_jmp32))
                         break;
 
                 /* try to recompute the bound of reg1 if reg2 is a const and
                  * is exactly the edge of reg1.
                  */
                 val = reg_const_value(reg2, is_jmp32);
                 if (is_jmp32) {
                         /* u32_min_value is not equal to 0xffffffff at this point,
                          * because otherwise u32_max_value is 0xffffffff as well,
                          * in such a case both reg1 and reg2 would be constants,
                          * jump would be predicted and reg_set_min_max() won't
                          * be called.
                          *
                          * Same reasoning works for all {u,s}{min,max}{32,64} cases
                          * below.
                          */
                         if (reg1->u32_min_value == (u32)val)
                                 reg1->u32_min_value++;
                         if (reg1->u32_max_value == (u32)val)
                                 reg1->u32_max_value--;
                         if (reg1->s32_min_value == (s32)val)
                                 reg1->s32_min_value++;
                         if (reg1->s32_max_value == (s32)val)
                                 reg1->s32_max_value--;
                 } else {
                         if (reg1->umin_value == (u64)val)
                                 reg1->umin_value++;
                         if (reg1->umax_value == (u64)val)
                                 reg1->umax_value--;
                         if (reg1->smin_value == (s64)val)
                                 reg1->smin_value++;
                         if (reg1->smax_value == (s64)val)
                                 reg1->smax_value--;
                 }
                 break;
         case BPF_JSET:
                 if (!is_reg_const(reg2, is_jmp32))
                         swap(reg1, reg2);
                 if (!is_reg_const(reg2, is_jmp32))
                         break;
                 val = reg_const_value(reg2, is_jmp32);
                 /* BPF_JSET (i.e., TRUE branch, *not* BPF_JSET | BPF_X)
                  * requires single bit to learn something useful. E.g., if we
                  * know that `r1 & 0x3` is true, then which bits (0, 1, or both)
                  * are actually set? We can learn something definite only if
                  * it's a single-bit value to begin with.
                  *
                  * BPF_JSET | BPF_X (i.e., negation of BPF_JSET) doesn't have
                  * this restriction. I.e., !(r1 & 0x3) means neither bit 0 nor
                  * bit 1 is set, which we can readily use in adjustments.
                  */
                 if (!is_power_of_2(val))
                         break;
                 if (is_jmp32) {
                         t = tnum_or(tnum_subreg(reg1->var_off), tnum_const(val));
                         reg1->var_off = tnum_with_subreg(reg1->var_off, t);
                 } else {
                         reg1->var_off = tnum_or(reg1->var_off, tnum_const(val));
                 }
                 break;
         case BPF_JSET | BPF_X: /* reverse of BPF_JSET, see rev_opcode() */
                 if (!is_reg_const(reg2, is_jmp32))
                         swap(reg1, reg2);
                 if (!is_reg_const(reg2, is_jmp32))
                         break;
                 val = reg_const_value(reg2, is_jmp32);
                 if (is_jmp32) {
                         t = tnum_and(tnum_subreg(reg1->var_off), tnum_const(~val));
                         reg1->var_off = tnum_with_subreg(reg1->var_off, t);
                 } else {
                         reg1->var_off = tnum_and(reg1->var_off, tnum_const(~val));
                 }
                 break;
         case BPF_JLE:
                 if (is_jmp32) {
                         reg1->u32_max_value = min(reg1->u32_max_value, reg2->u32_max_value);
                         reg2->u32_min_value = max(reg1->u32_min_value, reg2->u32_min_value);
                 } else {
                         reg1->umax_value = min(reg1->umax_value, reg2->umax_value);
                         reg2->umin_value = max(reg1->umin_value, reg2->umin_value);
                 }
                 break;
         case BPF_JLT:
                 if (is_jmp32) {
                         reg1->u32_max_value = min(reg1->u32_max_value, reg2->u32_max_value - 1);
                         reg2->u32_min_value = max(reg1->u32_min_value + 1, reg2->u32_min_value);
                 } else {
                         reg1->umax_value = min(reg1->umax_value, reg2->umax_value - 1);
                         reg2->umin_value = max(reg1->umin_value + 1, reg2->umin_value);
                 }
                 break;
         case BPF_JSLE:
                 if (is_jmp32) {
                         reg1->s32_max_value = min(reg1->s32_max_value, reg2->s32_max_value);
                         reg2->s32_min_value = max(reg1->s32_min_value, reg2->s32_min_value);
                 } else {
                         reg1->smax_value = min(reg1->smax_value, reg2->smax_value);
                         reg2->smin_value = max(reg1->smin_value, reg2->smin_value);
                 }
                 break;
         case BPF_JSLT:
                 if (is_jmp32) {
                         reg1->s32_max_value = min(reg1->s32_max_value, reg2->s32_max_value - 1);
                         reg2->s32_min_value = max(reg1->s32_min_value + 1, reg2->s32_min_value);
                 } else {
                         reg1->smax_value = min(reg1->smax_value, reg2->smax_value - 1);
                         reg2->smin_value = max(reg1->smin_value + 1, reg2->smin_value);
                 }
                 break;
         default:
                 return;
         }
 }
 
 /* Adjusts the register min/max values in the case that the dst_reg and
  * src_reg are both SCALAR_VALUE registers (or we are simply doing a BPF_K
  * check, in which case we have a fake SCALAR_VALUE representing insn->imm).
  * Technically we can do similar adjustments for pointers to the same object,
  * but we don't support that right now.
  */
 static int reg_set_min_max(struct bpf_verifier_env *env,
                            struct bpf_reg_state *true_reg1,
                            struct bpf_reg_state *true_reg2,
                            struct bpf_reg_state *false_reg1,
                            struct bpf_reg_state *false_reg2,
                            u8 opcode, bool is_jmp32)
 {
         int err;
 
         /* If either register is a pointer, we can't learn anything about its
          * variable offset from the compare (unless they were a pointer into
          * the same object, but we don't bother with that).
          */
         if (false_reg1->type != SCALAR_VALUE || false_reg2->type != SCALAR_VALUE)
                 return 0;
 
         /* fallthrough (FALSE) branch */
         regs_refine_cond_op(false_reg1, false_reg2, rev_opcode(opcode), is_jmp32);
         reg_bounds_sync(false_reg1);
         reg_bounds_sync(false_reg2);
 
         /* jump (TRUE) branch */
         regs_refine_cond_op(true_reg1, true_reg2, opcode, is_jmp32);
         reg_bounds_sync(true_reg1);
         reg_bounds_sync(true_reg2);
 
         err = reg_bounds_sanity_check(env, true_reg1, "true_reg1");
         err = err ?: reg_bounds_sanity_check(env, true_reg2, "true_reg2");
         err = err ?: reg_bounds_sanity_check(env, false_reg1, "false_reg1");
         err = err ?: reg_bounds_sanity_check(env, false_reg2, "false_reg2");
         return err;
 }
 
 static void mark_ptr_or_null_reg(struct bpf_func_state *state,
                                  struct bpf_reg_state *reg, u32 id,
                                  bool is_null)
 {
         if (type_may_be_null(reg->type) && reg->id == id &&
             (is_rcu_reg(reg) || !WARN_ON_ONCE(!reg->id))) {
                 /* Old offset (both fixed and variable parts) should have been
                  * known-zero, because we don't allow pointer arithmetic on
                  * pointers that might be NULL. If we see this happening, don't
                  * convert the register.
                  *
                  * But in some cases, some helpers that return local kptrs
                  * advance offset for the returned pointer. In those cases, it
                  * is fine to expect to see reg->off.
                  */
                 if (WARN_ON_ONCE(reg->smin_value || reg->smax_value || !tnum_equals_const(reg->var_off, 0)))
                         return;
                 if (!(type_is_ptr_alloc_obj(reg->type) || type_is_non_owning_ref(reg->type)) &&
                     WARN_ON_ONCE(reg->off))
                         return;
 
                 if (is_null) {
                         reg->type = SCALAR_VALUE;
                         /* We don't need id and ref_obj_id from this point
                          * onwards anymore, thus we should better reset it,
                          * so that state pruning has chances to take effect.
                          */
                         reg->id = 0;
                         reg->ref_obj_id = 0;
 
                         return;
                 }
 
                 mark_ptr_not_null_reg(reg);
 
                 if (!reg_may_point_to_spin_lock(reg)) {
                         /* For not-NULL ptr, reg->ref_obj_id will be reset
                          * in release_reference().
                          *
                          * reg->id is still used by spin_lock ptr. Other
                          * than spin_lock ptr type, reg->id can be reset.
                          */
                         reg->id = 0;
                 }
         }
 }
 
 /* The logic is similar to find_good_pkt_pointers(), both could eventually
  * be folded together at some point.
  */
 static void mark_ptr_or_null_regs(struct bpf_verifier_state *vstate, u32 regno,
                                   bool is_null)
 {
         struct bpf_func_state *state = vstate->frame[vstate->curframe];
         struct bpf_reg_state *regs = state->regs, *reg;
         u32 ref_obj_id = regs[regno].ref_obj_id;
         u32 id = regs[regno].id;
 
         if (ref_obj_id && ref_obj_id == id && is_null)
                 /* regs[regno] is in the " == NULL" branch.
                  * No one could have freed the reference state before
                  * doing the NULL check.
                  */
                 WARN_ON_ONCE(release_reference_state(state, id));
 
         bpf_for_each_reg_in_vstate(vstate, state, reg, ({
                 mark_ptr_or_null_reg(state, reg, id, is_null);
         }));
 }
 
 static bool try_match_pkt_pointers(const struct bpf_insn *insn,
                                    struct bpf_reg_state *dst_reg,
                                    struct bpf_reg_state *src_reg,
                                    struct bpf_verifier_state *this_branch,
                                    struct bpf_verifier_state *other_branch)
 {
         if (BPF_SRC(insn->code) != BPF_X)
                 return false;
 
         /* Pointers are always 64-bit. */
         if (BPF_CLASS(insn->code) == BPF_JMP32)
                 return false;
 
         switch (BPF_OP(insn->code)) {
         case BPF_JGT:
                 if ((dst_reg->type == PTR_TO_PACKET &&
                      src_reg->type == PTR_TO_PACKET_END) ||
                     (dst_reg->type == PTR_TO_PACKET_META &&
                      reg_is_init_pkt_pointer(src_reg, PTR_TO_PACKET))) {
                         /* pkt_data' > pkt_end, pkt_meta' > pkt_data */
                         find_good_pkt_pointers(this_branch, dst_reg,
                                                dst_reg->type, false);
                         mark_pkt_end(other_branch, insn->dst_reg, true);
                 } else if ((dst_reg->type == PTR_TO_PACKET_END &&
                             src_reg->type == PTR_TO_PACKET) ||
                            (reg_is_init_pkt_pointer(dst_reg, PTR_TO_PACKET) &&
                             src_reg->type == PTR_TO_PACKET_META)) {
                         /* pkt_end > pkt_data', pkt_data > pkt_meta' */
                         find_good_pkt_pointers(other_branch, src_reg,
                                                src_reg->type, true);
                         mark_pkt_end(this_branch, insn->src_reg, false);
                 } else {
                         return false;
                 }
                 break;
         case BPF_JLT:
                 if ((dst_reg->type == PTR_TO_PACKET &&
                      src_reg->type == PTR_TO_PACKET_END) ||
                     (dst_reg->type == PTR_TO_PACKET_META &&
                      reg_is_init_pkt_pointer(src_reg, PTR_TO_PACKET))) {
                         /* pkt_data' < pkt_end, pkt_meta' < pkt_data */
                         find_good_pkt_pointers(other_branch, dst_reg,
                                                dst_reg->type, true);
                         mark_pkt_end(this_branch, insn->dst_reg, false);
                 } else if ((dst_reg->type == PTR_TO_PACKET_END &&
                             src_reg->type == PTR_TO_PACKET) ||
                            (reg_is_init_pkt_pointer(dst_reg, PTR_TO_PACKET) &&
                             src_reg->type == PTR_TO_PACKET_META)) {
                         /* pkt_end < pkt_data', pkt_data > pkt_meta' */
                         find_good_pkt_pointers(this_branch, src_reg,
                                                src_reg->type, false);
                         mark_pkt_end(other_branch, insn->src_reg, true);
                 } else {
                         return false;
                 }
                 break;
         case BPF_JGE:
                 if ((dst_reg->type == PTR_TO_PACKET &&
                      src_reg->type == PTR_TO_PACKET_END) ||
                     (dst_reg->type == PTR_TO_PACKET_META &&
                      reg_is_init_pkt_pointer(src_reg, PTR_TO_PACKET))) {
                         /* pkt_data' >= pkt_end, pkt_meta' >= pkt_data */
                         find_good_pkt_pointers(this_branch, dst_reg,
                                                dst_reg->type, true);
                         mark_pkt_end(other_branch, insn->dst_reg, false);
                 } else if ((dst_reg->type == PTR_TO_PACKET_END &&
                             src_reg->type == PTR_TO_PACKET) ||
                            (reg_is_init_pkt_pointer(dst_reg, PTR_TO_PACKET) &&
                             src_reg->type == PTR_TO_PACKET_META)) {
                         /* pkt_end >= pkt_data', pkt_data >= pkt_meta' */
                         find_good_pkt_pointers(other_branch, src_reg,
                                                src_reg->type, false);
                         mark_pkt_end(this_branch, insn->src_reg, true);
                 } else {
                         return false;
                 }
                 break;
         case BPF_JLE:
                 if ((dst_reg->type == PTR_TO_PACKET &&
                      src_reg->type == PTR_TO_PACKET_END) ||
                     (dst_reg->type == PTR_TO_PACKET_META &&
                      reg_is_init_pkt_pointer(src_reg, PTR_TO_PACKET))) {
                         /* pkt_data' <= pkt_end, pkt_meta' <= pkt_data */
                         find_good_pkt_pointers(other_branch, dst_reg,
                                                dst_reg->type, false);
                         mark_pkt_end(this_branch, insn->dst_reg, true);
                 } else if ((dst_reg->type == PTR_TO_PACKET_END &&
                             src_reg->type == PTR_TO_PACKET) ||
                            (reg_is_init_pkt_pointer(dst_reg, PTR_TO_PACKET) &&
                             src_reg->type == PTR_TO_PACKET_META)) {
                         /* pkt_end <= pkt_data', pkt_data <= pkt_meta' */
                         find_good_pkt_pointers(this_branch, src_reg,
                                                src_reg->type, true);
                         mark_pkt_end(other_branch, insn->src_reg, false);
                 } else {
                         return false;
                 }
                 break;
         default:
                 return false;
         }
 
         return true;
 }
 
 static void find_equal_scalars(struct bpf_verifier_state *vstate,
                                struct bpf_reg_state *known_reg)
 {
         struct bpf_reg_state fake_reg;
         struct bpf_func_state *state;
         struct bpf_reg_state *reg;
 
         bpf_for_each_reg_in_vstate(vstate, state, reg, ({
                 if (reg->type != SCALAR_VALUE || reg == known_reg)
                         continue;
                 if ((reg->id & ~BPF_ADD_CONST) != (known_reg->id & ~BPF_ADD_CONST))
                         continue;
                 if ((!(reg->id & BPF_ADD_CONST) && !(known_reg->id & BPF_ADD_CONST)) ||
                     reg->off == known_reg->off) {
                         copy_register_state(reg, known_reg);
                 } else {
                         s32 saved_off = reg->off;
 
                         fake_reg.type = SCALAR_VALUE;
                         __mark_reg_known(&fake_reg, (s32)reg->off - (s32)known_reg->off);
 
                         /* reg = known_reg; reg += delta */
                         copy_register_state(reg, known_reg);
                         /*
                          * Must preserve off, id and add_const flag,
                          * otherwise another find_equal_scalars() will be incorrect.
                          */
                         reg->off = saved_off;
 
                         scalar32_min_max_add(reg, &fake_reg);
                         scalar_min_max_add(reg, &fake_reg);
                         reg->var_off = tnum_add(reg->var_off, fake_reg.var_off);
                 }
         }));
 }
 
 static int check_cond_jmp_op(struct bpf_verifier_env *env,
                              struct bpf_insn *insn, int *insn_idx)
 {
         struct bpf_verifier_state *this_branch = env->cur_state;
         struct bpf_verifier_state *other_branch;
         struct bpf_reg_state *regs = this_branch->frame[this_branch->curframe]->regs;
         struct bpf_reg_state *dst_reg, *other_branch_regs, *src_reg = NULL;
         struct bpf_reg_state *eq_branch_regs;
         u8 opcode = BPF_OP(insn->code);
         bool is_jmp32;
         int pred = -1;
         int err;
 
         /* Only conditional jumps are expected to reach here. */
         if (opcode == BPF_JA || opcode > BPF_JCOND) {
                 verbose(env, "invalid BPF_JMP/JMP32 opcode %x\n", opcode);
                 return -EINVAL;
         }
 
         if (opcode == BPF_JCOND) {
                 struct bpf_verifier_state *cur_st = env->cur_state, *queued_st, *prev_st;
                 int idx = *insn_idx;
 
                 if (insn->code != (BPF_JMP | BPF_JCOND) ||
                     insn->src_reg != BPF_MAY_GOTO ||
                     insn->dst_reg || insn->imm || insn->off == 0) {
                         verbose(env, "invalid may_goto off %d imm %d\n",
                                 insn->off, insn->imm);
                         return -EINVAL;
                 }
                 prev_st = find_prev_entry(env, cur_st->parent, idx);
 
                 /* branch out 'fallthrough' insn as a new state to explore */
                 queued_st = push_stack(env, idx + 1, idx, false);
                 if (!queued_st)
                         return -ENOMEM;
 
                 queued_st->may_goto_depth++;
                 if (prev_st)
                         widen_imprecise_scalars(env, prev_st, queued_st);
                 *insn_idx += insn->off;
                 return 0;
         }
 
         /* check src2 operand */
         err = check_reg_arg(env, insn->dst_reg, SRC_OP);
         if (err)
                 return err;
 
         dst_reg = &regs[insn->dst_reg];
         if (BPF_SRC(insn->code) == BPF_X) {
                 if (insn->imm != 0) {
                         verbose(env, "BPF_JMP/JMP32 uses reserved fields\n");
                         return -EINVAL;
                 }
 
                 /* check src1 operand */
                 err = check_reg_arg(env, insn->src_reg, SRC_OP);
                 if (err)
                         return err;
 
                 src_reg = &regs[insn->src_reg];
                 if (!(reg_is_pkt_pointer_any(dst_reg) && reg_is_pkt_pointer_any(src_reg)) &&
                     is_pointer_value(env, insn->src_reg)) {
                         verbose(env, "R%d pointer comparison prohibited\n",
                                 insn->src_reg);
                         return -EACCES;
                 }
         } else {
                 if (insn->src_reg != BPF_REG_0) {
                         verbose(env, "BPF_JMP/JMP32 uses reserved fields\n");
                         return -EINVAL;
                 }
                 src_reg = &env->fake_reg[0];
                 memset(src_reg, 0, sizeof(*src_reg));
                 src_reg->type = SCALAR_VALUE;
                 __mark_reg_known(src_reg, insn->imm);
         }
 
         is_jmp32 = BPF_CLASS(insn->code) == BPF_JMP32;
         pred = is_branch_taken(dst_reg, src_reg, opcode, is_jmp32);
         if (pred >= 0) {
                 /* If we get here with a dst_reg pointer type it is because
                  * above is_branch_taken() special cased the 0 comparison.
                  */
                 if (!__is_pointer_value(false, dst_reg))
                         err = mark_chain_precision(env, insn->dst_reg);
                 if (BPF_SRC(insn->code) == BPF_X && !err &&
                     !__is_pointer_value(false, src_reg))
                         err = mark_chain_precision(env, insn->src_reg);
                 if (err)
                         return err;
         }
 
         if (pred == 1) {
                 /* Only follow the goto, ignore fall-through. If needed, push
                  * the fall-through branch for simulation under speculative
                  * execution.
                  */
                 if (!env->bypass_spec_v1 &&
                     !sanitize_speculative_path(env, insn, *insn_idx + 1,
                                                *insn_idx))
                         return -EFAULT;
                 if (env->log.level & BPF_LOG_LEVEL)
                         print_insn_state(env, this_branch->frame[this_branch->curframe]);
                 *insn_idx += insn->off;
                 return 0;
         } else if (pred == 0) {
                 /* Only follow the fall-through branch, since that's where the
                  * program will go. If needed, push the goto branch for
                  * simulation under speculative execution.
                  */
                 if (!env->bypass_spec_v1 &&
                     !sanitize_speculative_path(env, insn,
                                                *insn_idx + insn->off + 1,
                                                *insn_idx))
                         return -EFAULT;
                 if (env->log.level & BPF_LOG_LEVEL)
                         print_insn_state(env, this_branch->frame[this_branch->curframe]);
                 return 0;
         }
 
         other_branch = push_stack(env, *insn_idx + insn->off + 1, *insn_idx,
                                   false);
         if (!other_branch)
                 return -EFAULT;
         other_branch_regs = other_branch->frame[other_branch->curframe]->regs;
 
         if (BPF_SRC(insn->code) == BPF_X) {
                 err = reg_set_min_max(env,
                                       &other_branch_regs[insn->dst_reg],
                                       &other_branch_regs[insn->src_reg],
                                       dst_reg, src_reg, opcode, is_jmp32);
         } else /* BPF_SRC(insn->code) == BPF_K */ {
                 /* reg_set_min_max() can mangle the fake_reg. Make a copy
                  * so that these are two different memory locations. The
                  * src_reg is not used beyond here in context of K.
                  */
                 memcpy(&env->fake_reg[1], &env->fake_reg[0],
                        sizeof(env->fake_reg[0]));
                 err = reg_set_min_max(env,
                                       &other_branch_regs[insn->dst_reg],
                                       &env->fake_reg[0],
                                       dst_reg, &env->fake_reg[1],
                                       opcode, is_jmp32);
         }
         if (err)
                 return err;
 
         if (BPF_SRC(insn->code) == BPF_X &&
             src_reg->type == SCALAR_VALUE && src_reg->id &&
             !WARN_ON_ONCE(src_reg->id != other_branch_regs[insn->src_reg].id)) {
                 find_equal_scalars(this_branch, src_reg);
                 find_equal_scalars(other_branch, &other_branch_regs[insn->src_reg]);
         }
         if (dst_reg->type == SCALAR_VALUE && dst_reg->id &&
             !WARN_ON_ONCE(dst_reg->id != other_branch_regs[insn->dst_reg].id)) {
                 find_equal_scalars(this_branch, dst_reg);
                 find_equal_scalars(other_branch, &other_branch_regs[insn->dst_reg]);
         }
 
         /* if one pointer register is compared to another pointer
          * register check if PTR_MAYBE_NULL could be lifted.
          * E.g. register A - maybe null
          *      register B - not null
          * for JNE A, B, ... - A is not null in the false branch;
          * for JEQ A, B, ... - A is not null in the true branch.
          *
          * Since PTR_TO_BTF_ID points to a kernel struct that does
          * not need to be null checked by the BPF program, i.e.,
          * could be null even without PTR_MAYBE_NULL marking, so
          * only propagate nullness when neither reg is that type.
          */
         if (!is_jmp32 && BPF_SRC(insn->code) == BPF_X &&
             __is_pointer_value(false, src_reg) && __is_pointer_value(false, dst_reg) &&
             type_may_be_null(src_reg->type) != type_may_be_null(dst_reg->type) &&
             base_type(src_reg->type) != PTR_TO_BTF_ID &&
             base_type(dst_reg->type) != PTR_TO_BTF_ID) {
                 eq_branch_regs = NULL;
                 switch (opcode) {
                 case BPF_JEQ:
                         eq_branch_regs = other_branch_regs;
                         break;
                 case BPF_JNE:
                         eq_branch_regs = regs;
                         break;
                 default:
                         /* do nothing */
                         break;
                 }
                 if (eq_branch_regs) {
                         if (type_may_be_null(src_reg->type))
                                 mark_ptr_not_null_reg(&eq_branch_regs[insn->src_reg]);
                         else
                                 mark_ptr_not_null_reg(&eq_branch_regs[insn->dst_reg]);
                 }
         }
 
         /* detect if R == 0 where R is returned from bpf_map_lookup_elem().
          * NOTE: these optimizations below are related with pointer comparison
          *       which will never be JMP32.
          */
         if (!is_jmp32 && BPF_SRC(insn->code) == BPF_K &&
             insn->imm == 0 && (opcode == BPF_JEQ || opcode == BPF_JNE) &&
             type_may_be_null(dst_reg->type)) {
                 /* Mark all identical registers in each branch as either
                  * safe or unknown depending R == 0 or R != 0 conditional.
                  */
                 mark_ptr_or_null_regs(this_branch, insn->dst_reg,
                                       opcode == BPF_JNE);
                 mark_ptr_or_null_regs(other_branch, insn->dst_reg,
                                       opcode == BPF_JEQ);
         } else if (!try_match_pkt_pointers(insn, dst_reg, &regs[insn->src_reg],
                                            this_branch, other_branch) &&
                    is_pointer_value(env, insn->dst_reg)) {
                 verbose(env, "R%d pointer comparison prohibited\n",
                         insn->dst_reg);
                 return -EACCES;
         }
         if (env->log.level & BPF_LOG_LEVEL)
                 print_insn_state(env, this_branch->frame[this_branch->curframe]);
         return 0;
 }
 
 /* verify BPF_LD_IMM64 instruction */
 static int check_ld_imm(struct bpf_verifier_env *env, struct bpf_insn *insn)
 {
         struct bpf_insn_aux_data *aux = cur_aux(env);
         struct bpf_reg_state *regs = cur_regs(env);
         struct bpf_reg_state *dst_reg;
         struct bpf_map *map;
         int err;
 
         if (BPF_SIZE(insn->code) != BPF_DW) {
                 verbose(env, "invalid BPF_LD_IMM insn\n");
                 return -EINVAL;
         }
         if (insn->off != 0) {
                 verbose(env, "BPF_LD_IMM64 uses reserved fields\n");
                 return -EINVAL;
         }
 
         err = check_reg_arg(env, insn->dst_reg, DST_OP);
         if (err)
                 return err;
 
         dst_reg = &regs[insn->dst_reg];
         if (insn->src_reg == 0) {
                 u64 imm = ((u64)(insn + 1)->imm << 32) | (u32)insn->imm;
 
                 dst_reg->type = SCALAR_VALUE;
                 __mark_reg_known(&regs[insn->dst_reg], imm);
                 return 0;
         }
 
         /* All special src_reg cases are listed below. From this point onwards
          * we either succeed and assign a corresponding dst_reg->type after
          * zeroing the offset, or fail and reject the program.
          */
         mark_reg_known_zero(env, regs, insn->dst_reg);
 
         if (insn->src_reg == BPF_PSEUDO_BTF_ID) {
                 dst_reg->type = aux->btf_var.reg_type;
                 switch (base_type(dst_reg->type)) {
                 case PTR_TO_MEM:
                         dst_reg->mem_size = aux->btf_var.mem_size;
                         break;
                 case PTR_TO_BTF_ID:
                         dst_reg->btf = aux->btf_var.btf;
                         dst_reg->btf_id = aux->btf_var.btf_id;
                         break;
                 default:
                         verbose(env, "bpf verifier is misconfigured\n");
                         return -EFAULT;
                 }
                 return 0;
         }
 
         if (insn->src_reg == BPF_PSEUDO_FUNC) {
                 struct bpf_prog_aux *aux = env->prog->aux;
                 u32 subprogno = find_subprog(env,
                                              env->insn_idx + insn->imm + 1);
 
                 if (!aux->func_info) {
                         verbose(env, "missing btf func_info\n");
                         return -EINVAL;
                 }
                 if (aux->func_info_aux[subprogno].linkage != BTF_FUNC_STATIC) {
                         verbose(env, "callback function not static\n");
                         return -EINVAL;
                 }
 
                 dst_reg->type = PTR_TO_FUNC;
                 dst_reg->subprogno = subprogno;
                 return 0;
         }
 
         map = env->used_maps[aux->map_index];
         dst_reg->map_ptr = map;
 
         if (insn->src_reg == BPF_PSEUDO_MAP_VALUE ||
             insn->src_reg == BPF_PSEUDO_MAP_IDX_VALUE) {
                 if (map->map_type == BPF_MAP_TYPE_ARENA) {
                         __mark_reg_unknown(env, dst_reg);
                         return 0;
                 }
                 dst_reg->type = PTR_TO_MAP_VALUE;
                 dst_reg->off = aux->map_off;
                 WARN_ON_ONCE(map->max_entries != 1);
                 /* We want reg->id to be same (0) as map_value is not distinct */
         } else if (insn->src_reg == BPF_PSEUDO_MAP_FD ||
                    insn->src_reg == BPF_PSEUDO_MAP_IDX) {
                 dst_reg->type = CONST_PTR_TO_MAP;
         } else {
                 verbose(env, "bpf verifier is misconfigured\n");
                 return -EINVAL;
         }
 
         return 0;
 }
 
 static bool may_access_skb(enum bpf_prog_type type)
 {
         switch (type) {
         case BPF_PROG_TYPE_SOCKET_FILTER:
         case BPF_PROG_TYPE_SCHED_CLS:
         case BPF_PROG_TYPE_SCHED_ACT:
                 return true;
         default:
                 return false;
         }
 }
 
 /* verify safety of LD_ABS|LD_IND instructions:
  * - they can only appear in the programs where ctx == skb
  * - since they are wrappers of function calls, they scratch R1-R5 registers,
  *   preserve R6-R9, and store return value into R0
  *
  * Implicit input:
  *   ctx == skb == R6 == CTX
  *
  * Explicit input:
  *   SRC == any register
  *   IMM == 32-bit immediate
  *
  * Output:
  *   R0 - 8/16/32-bit skb data converted to cpu endianness
  */
 static int check_ld_abs(struct bpf_verifier_env *env, struct bpf_insn *insn)
 {
         struct bpf_reg_state *regs = cur_regs(env);
         static const int ctx_reg = BPF_REG_6;
         u8 mode = BPF_MODE(insn->code);
         int i, err;
 
         if (!may_access_skb(resolve_prog_type(env->prog))) {
                 verbose(env, "BPF_LD_[ABS|IND] instructions not allowed for this program type\n");
                 return -EINVAL;
         }
 
         if (!env->ops->gen_ld_abs) {
                 verbose(env, "bpf verifier is misconfigured\n");
                 return -EINVAL;
         }
 
         if (insn->dst_reg != BPF_REG_0 || insn->off != 0 ||
             BPF_SIZE(insn->code) == BPF_DW ||
             (mode == BPF_ABS && insn->src_reg != BPF_REG_0)) {
                 verbose(env, "BPF_LD_[ABS|IND] uses reserved fields\n");
                 return -EINVAL;
         }
 
         /* check whether implicit source operand (register R6) is readable */
         err = check_reg_arg(env, ctx_reg, SRC_OP);
         if (err)
                 return err;
 
         /* Disallow usage of BPF_LD_[ABS|IND] with reference tracking, as
          * gen_ld_abs() may terminate the program at runtime, leading to
          * reference leak.
          */
         err = check_reference_leak(env, false);
         if (err) {
                 verbose(env, "BPF_LD_[ABS|IND] cannot be mixed with socket references\n");
                 return err;
         }
 
         if (env->cur_state->active_lock.ptr) {
                 verbose(env, "BPF_LD_[ABS|IND] cannot be used inside bpf_spin_lock-ed region\n");
                 return -EINVAL;
         }
 
         if (env->cur_state->active_rcu_lock) {
                 verbose(env, "BPF_LD_[ABS|IND] cannot be used inside bpf_rcu_read_lock-ed region\n");
                 return -EINVAL;
         }
 
         if (env->cur_state->active_preempt_lock) {
                 verbose(env, "BPF_LD_[ABS|IND] cannot be used inside bpf_preempt_disable-ed region\n");
                 return -EINVAL;
         }
 
         if (regs[ctx_reg].type != PTR_TO_CTX) {
                 verbose(env,
                         "at the time of BPF_LD_ABS|IND R6 != pointer to skb\n");
                 return -EINVAL;
         }
 
         if (mode == BPF_IND) {
                 /* check explicit source operand */
                 err = check_reg_arg(env, insn->src_reg, SRC_OP);
                 if (err)
                         return err;
         }
 
         err = check_ptr_off_reg(env, &regs[ctx_reg], ctx_reg);
         if (err < 0)
                 return err;
 
         /* reset caller saved regs to unreadable */
         for (i = 0; i < CALLER_SAVED_REGS; i++) {
                 mark_reg_not_init(env, regs, caller_saved[i]);
                 check_reg_arg(env, caller_saved[i], DST_OP_NO_MARK);
         }
 
         /* mark destination R0 register as readable, since it contains
          * the value fetched from the packet.
          * Already marked as written above.
          */
         mark_reg_unknown(env, regs, BPF_REG_0);
         /* ld_abs load up to 32-bit skb data. */
         regs[BPF_REG_0].subreg_def = env->insn_idx + 1;
         return 0;
 }
 
 static int check_return_code(struct bpf_verifier_env *env, int regno, const char *reg_name)
 {
         const char *exit_ctx = "At program exit";
         struct tnum enforce_attach_type_range = tnum_unknown;
         const struct bpf_prog *prog = env->prog;
         struct bpf_reg_state *reg;
         struct bpf_retval_range range = retval_range(0, 1);
         enum bpf_prog_type prog_type = resolve_prog_type(env->prog);
         int err;
         struct bpf_func_state *frame = env->cur_state->frame[0];
         const bool is_subprog = frame->subprogno;
         bool return_32bit = false;
 
         /* LSM and struct_ops func-ptr's return type could be "void" */
         if (!is_subprog || frame->in_exception_callback_fn) {
                 switch (prog_type) {
                 case BPF_PROG_TYPE_LSM:
                         if (prog->expected_attach_type == BPF_LSM_CGROUP)
                                 /* See below, can be 0 or 0-1 depending on hook. */
                                 break;
                         fallthrough;
                 case BPF_PROG_TYPE_STRUCT_OPS:
                         if (!prog->aux->attach_func_proto->type)
                                 return 0;
                         break;
                 default:
                         break;
                 }
         }
 
         /* eBPF calling convention is such that R0 is used
          * to return the value from eBPF program.
          * Make sure that it's readable at this time
          * of bpf_exit, which means that program wrote
          * something into it earlier
          */
         err = check_reg_arg(env, regno, SRC_OP);
         if (err)
                 return err;
 
         if (is_pointer_value(env, regno)) {
                 verbose(env, "R%d leaks addr as return value\n", regno);
                 return -EACCES;
         }
 
         reg = cur_regs(env) + regno;
 
         if (frame->in_async_callback_fn) {
                 /* enforce return zero from async callbacks like timer */
                 exit_ctx = "At async callback return";
                 range = retval_range(0, 0);
                 goto enforce_retval;
         }
 
         if (is_subprog && !frame->in_exception_callback_fn) {
                 if (reg->type != SCALAR_VALUE) {
                         verbose(env, "At subprogram exit the register R%d is not a scalar value (%s)\n",
                                 regno, reg_type_str(env, reg->type));
                         return -EINVAL;
                 }
                 return 0;
         }
 
         switch (prog_type) {
         case BPF_PROG_TYPE_CGROUP_SOCK_ADDR:
                 if (env->prog->expected_attach_type == BPF_CGROUP_UDP4_RECVMSG ||
                     env->prog->expected_attach_type == BPF_CGROUP_UDP6_RECVMSG ||
                     env->prog->expected_attach_type == BPF_CGROUP_UNIX_RECVMSG ||
                     env->prog->expected_attach_type == BPF_CGROUP_INET4_GETPEERNAME ||
                     env->prog->expected_attach_type == BPF_CGROUP_INET6_GETPEERNAME ||
                     env->prog->expected_attach_type == BPF_CGROUP_UNIX_GETPEERNAME ||
                     env->prog->expected_attach_type == BPF_CGROUP_INET4_GETSOCKNAME ||
                     env->prog->expected_attach_type == BPF_CGROUP_INET6_GETSOCKNAME ||
                     env->prog->expected_attach_type == BPF_CGROUP_UNIX_GETSOCKNAME)
                         range = retval_range(1, 1);
                 if (env->prog->expected_attach_type == BPF_CGROUP_INET4_BIND ||
                     env->prog->expected_attach_type == BPF_CGROUP_INET6_BIND)
                         range = retval_range(0, 3);
                 break;
         case BPF_PROG_TYPE_CGROUP_SKB:
                 if (env->prog->expected_attach_type == BPF_CGROUP_INET_EGRESS) {
                         range = retval_range(0, 3);
                         enforce_attach_type_range = tnum_range(2, 3);
                 }
                 break;
         case BPF_PROG_TYPE_CGROUP_SOCK:
         case BPF_PROG_TYPE_SOCK_OPS:
         case BPF_PROG_TYPE_CGROUP_DEVICE:
         case BPF_PROG_TYPE_CGROUP_SYSCTL:
         case BPF_PROG_TYPE_CGROUP_SOCKOPT:
                 break;
         case BPF_PROG_TYPE_RAW_TRACEPOINT:
                 if (!env->prog->aux->attach_btf_id)
                         return 0;
                 range = retval_range(0, 0);
                 break;
         case BPF_PROG_TYPE_TRACING:
                 switch (env->prog->expected_attach_type) {
                 case BPF_TRACE_FENTRY:
                 case BPF_TRACE_FEXIT:
                         range = retval_range(0, 0);
                         break;
                 case BPF_TRACE_RAW_TP:
                 case BPF_MODIFY_RETURN:
                         return 0;
                 case BPF_TRACE_ITER:
                         break;
                 default:
                         return -ENOTSUPP;
                 }
                 break;
         case BPF_PROG_TYPE_SK_LOOKUP:
                 range = retval_range(SK_DROP, SK_PASS);
                 break;
 
         case BPF_PROG_TYPE_LSM:
                 if (env->prog->expected_attach_type != BPF_LSM_CGROUP) {
                         /* no range found, any return value is allowed */
                         if (!get_func_retval_range(env->prog, &range))
                                 return 0;
                         /* no restricted range, any return value is allowed */
                         if (range.minval == S32_MIN && range.maxval == S32_MAX)
                                 return 0;
                         return_32bit = true;
                 } else if (!env->prog->aux->attach_func_proto->type) {
                         /* Make sure programs that attach to void
                          * hooks don't try to modify return value.
                          */
                         range = retval_range(1, 1);
                 }
                 break;
 
         case BPF_PROG_TYPE_NETFILTER:
                 range = retval_range(NF_DROP, NF_ACCEPT);
                 break;
         case BPF_PROG_TYPE_EXT:
                 /* freplace program can return anything as its return value
                  * depends on the to-be-replaced kernel func or bpf program.
                  */
         default:
                 return 0;
         }
 
 enforce_retval:
         if (reg->type != SCALAR_VALUE) {
                 verbose(env, "%s the register R%d is not a known value (%s)\n",
                         exit_ctx, regno, reg_type_str(env, reg->type));
                 return -EINVAL;
         }
 
         err = mark_chain_precision(env, regno);
         if (err)
                 return err;
 
         if (!retval_range_within(range, reg, return_32bit)) {
                 verbose_invalid_scalar(env, reg, range, exit_ctx, reg_name);
                 if (!is_subprog &&
                     prog->expected_attach_type == BPF_LSM_CGROUP &&
                     prog_type == BPF_PROG_TYPE_LSM &&
                     !prog->aux->attach_func_proto->type)
                         verbose(env, "Note, BPF_LSM_CGROUP that attach to void LSM hooks can't modify return value!\n");
                 return -EINVAL;
         }
 
         if (!tnum_is_unknown(enforce_attach_type_range) &&
             tnum_in(enforce_attach_type_range, reg->var_off))
                 env->prog->enforce_expected_attach_type = 1;
         return 0;
 }
 
 /* non-recursive DFS pseudo code
  * 1  procedure DFS-iterative(G,v):
  * 2      label v as discovered
  * 3      let S be a stack
  * 4      S.push(v)
  * 5      while S is not empty
  * 6            t <- S.peek()
  * 7            if t is what we're looking for:
  * 8                return t
  * 9            for all edges e in G.adjacentEdges(t) do
  * 10               if edge e is already labelled
  * 11                   continue with the next edge
  * 12               w <- G.adjacentVertex(t,e)
  * 13               if vertex w is not discovered and not explored
  * 14                   label e as tree-edge
  * 15                   label w as discovered
  * 16                   S.push(w)
  * 17                   continue at 5
  * 18               else if vertex w is discovered
  * 19                   label e as back-edge
  * 20               else
  * 21                   // vertex w is explored
  * 22                   label e as forward- or cross-edge
  * 23           label t as explored
  * 24           S.pop()
  *
  * convention:
  * 0x10 - discovered
  * 0x11 - discovered and fall-through edge labelled
  * 0x12 - discovered and fall-through and branch edges labelled
  * 0x20 - explored
  */
 
 enum {
         DISCOVERED = 0x10,
         EXPLORED = 0x20,
         FALLTHROUGH = 1,
         BRANCH = 2,
 };
 
 static void mark_prune_point(struct bpf_verifier_env *env, int idx)
 {
         env->insn_aux_data[idx].prune_point = true;
 }
 
 static bool is_prune_point(struct bpf_verifier_env *env, int insn_idx)
 {
         return env->insn_aux_data[insn_idx].prune_point;
 }
 
 static void mark_force_checkpoint(struct bpf_verifier_env *env, int idx)
 {
         env->insn_aux_data[idx].force_checkpoint = true;
 }
 
 static bool is_force_checkpoint(struct bpf_verifier_env *env, int insn_idx)
 {
         return env->insn_aux_data[insn_idx].force_checkpoint;
 }
 
 static void mark_calls_callback(struct bpf_verifier_env *env, int idx)
 {
         env->insn_aux_data[idx].calls_callback = true;
 }
 
 static bool calls_callback(struct bpf_verifier_env *env, int insn_idx)
 {
         return env->insn_aux_data[insn_idx].calls_callback;
 }
 
 enum {
         DONE_EXPLORING = 0,
         KEEP_EXPLORING = 1,
 };
 
 /* t, w, e - match pseudo-code above:
  * t - index of current instruction
  * w - next instruction
  * e - edge
  */
 static int push_insn(int t, int w, int e, struct bpf_verifier_env *env)
 {
         int *insn_stack = env->cfg.insn_stack;
         int *insn_state = env->cfg.insn_state;
 
         if (e == FALLTHROUGH && insn_state[t] >= (DISCOVERED | FALLTHROUGH))
                 return DONE_EXPLORING;
 
         if (e == BRANCH && insn_state[t] >= (DISCOVERED | BRANCH))
                 return DONE_EXPLORING;
 
         if (w < 0 || w >= env->prog->len) {
                 verbose_linfo(env, t, "%d: ", t);
                 verbose(env, "jump out of range from insn %d to %d\n", t, w);
                 return -EINVAL;
         }
 
         if (e == BRANCH) {
                 /* mark branch target for state pruning */
                 mark_prune_point(env, w);
                 mark_jmp_point(env, w);
         }
 
         if (insn_state[w] == 0) {
                 /* tree-edge */
                 insn_state[t] = DISCOVERED | e;
                 insn_state[w] = DISCOVERED;
                 if (env->cfg.cur_stack >= env->prog->len)
                         return -E2BIG;
                 insn_stack[env->cfg.cur_stack++] = w;
                 return KEEP_EXPLORING;
         } else if ((insn_state[w] & 0xF0) == DISCOVERED) {
                 if (env->bpf_capable)
                         return DONE_EXPLORING;
                 verbose_linfo(env, t, "%d: ", t);
                 verbose_linfo(env, w, "%d: ", w);
                 verbose(env, "back-edge from insn %d to %d\n", t, w);
                 return -EINVAL;
         } else if (insn_state[w] == EXPLORED) {
                 /* forward- or cross-edge */
                 insn_state[t] = DISCOVERED | e;
         } else {
                 verbose(env, "insn state internal bug\n");
                 return -EFAULT;
         }
         return DONE_EXPLORING;
 }
 
 static int visit_func_call_insn(int t, struct bpf_insn *insns,
                                 struct bpf_verifier_env *env,
                                 bool visit_callee)
 {
         int ret, insn_sz;
 
         insn_sz = bpf_is_ldimm64(&insns[t]) ? 2 : 1;
         ret = push_insn(t, t + insn_sz, FALLTHROUGH, env);
         if (ret)
                 return ret;
 
         mark_prune_point(env, t + insn_sz);
         /* when we exit from subprog, we need to record non-linear history */
         mark_jmp_point(env, t + insn_sz);
 
         if (visit_callee) {
                 mark_prune_point(env, t);
                 ret = push_insn(t, t + insns[t].imm + 1, BRANCH, env);
         }
         return ret;
 }
 
 /* Visits the instruction at index t and returns one of the following:
  *  < 0 - an error occurred
  *  DONE_EXPLORING - the instruction was fully explored
  *  KEEP_EXPLORING - there is still work to be done before it is fully explored
  */
 static int visit_insn(int t, struct bpf_verifier_env *env)
 {
         struct bpf_insn *insns = env->prog->insnsi, *insn = &insns[t];
         int ret, off, insn_sz;
 
         if (bpf_pseudo_func(insn))
                 return visit_func_call_insn(t, insns, env, true);
 
         /* All non-branch instructions have a single fall-through edge. */
         if (BPF_CLASS(insn->code) != BPF_JMP &&
             BPF_CLASS(insn->code) != BPF_JMP32) {
                 insn_sz = bpf_is_ldimm64(insn) ? 2 : 1;
                 return push_insn(t, t + insn_sz, FALLTHROUGH, env);
         }
 
         switch (BPF_OP(insn->code)) {
         case BPF_EXIT:
                 return DONE_EXPLORING;
 
         case BPF_CALL:
                 if (is_async_callback_calling_insn(insn))
                         /* Mark this call insn as a prune point to trigger
                          * is_state_visited() check before call itself is
                          * processed by __check_func_call(). Otherwise new
                          * async state will be pushed for further exploration.
                          */
                         mark_prune_point(env, t);
                 /* For functions that invoke callbacks it is not known how many times
                  * callback would be called. Verifier models callback calling functions
                  * by repeatedly visiting callback bodies and returning to origin call
                  * instruction.
                  * In order to stop such iteration verifier needs to identify when a
                  * state identical some state from a previous iteration is reached.
                  * Check below forces creation of checkpoint before callback calling
                  * instruction to allow search for such identical states.
                  */
                 if (is_sync_callback_calling_insn(insn)) {
                         mark_calls_callback(env, t);
                         mark_force_checkpoint(env, t);
                         mark_prune_point(env, t);
                         mark_jmp_point(env, t);
                 }
                 if (insn->src_reg == BPF_PSEUDO_KFUNC_CALL) {
                         struct bpf_kfunc_call_arg_meta meta;
 
                         ret = fetch_kfunc_meta(env, insn, &meta, NULL);
                         if (ret == 0 && is_iter_next_kfunc(&meta)) {
                                 mark_prune_point(env, t);
                                 /* Checking and saving state checkpoints at iter_next() call
                                  * is crucial for fast convergence of open-coded iterator loop
                                  * logic, so we need to force it. If we don't do that,
                                  * is_state_visited() might skip saving a checkpoint, causing
                                  * unnecessarily long sequence of not checkpointed
                                  * instructions and jumps, leading to exhaustion of jump
                                  * history buffer, and potentially other undesired outcomes.
                                  * It is expected that with correct open-coded iterators
                                  * convergence will happen quickly, so we don't run a risk of
                                  * exhausting memory.
                                  */
                                 mark_force_checkpoint(env, t);
                         }
                 }
                 return visit_func_call_insn(t, insns, env, insn->src_reg == BPF_PSEUDO_CALL);
 
         case BPF_JA:
                 if (BPF_SRC(insn->code) != BPF_K)
                         return -EINVAL;
 
                 if (BPF_CLASS(insn->code) == BPF_JMP)
                         off = insn->off;
                 else
                         off = insn->imm;
 
                 /* unconditional jump with single edge */
                 ret = push_insn(t, t + off + 1, FALLTHROUGH, env);
                 if (ret)
                         return ret;
 
                 mark_prune_point(env, t + off + 1);
                 mark_jmp_point(env, t + off + 1);
 
                 return ret;
 
         default:
                 /* conditional jump with two edges */
                 mark_prune_point(env, t);
                 if (is_may_goto_insn(insn))
                         mark_force_checkpoint(env, t);
 
                 ret = push_insn(t, t + 1, FALLTHROUGH, env);
                 if (ret)
                         return ret;
 
                 return push_insn(t, t + insn->off + 1, BRANCH, env);
         }
 }
 
 /* non-recursive depth-first-search to detect loops in BPF program
  * loop == back-edge in directed graph
  */
 static int check_cfg(struct bpf_verifier_env *env)
 {
         int insn_cnt = env->prog->len;
         int *insn_stack, *insn_state;
         int ex_insn_beg, i, ret = 0;
         bool ex_done = false;
 
         insn_state = env->cfg.insn_state = kvcalloc(insn_cnt, sizeof(int), GFP_KERNEL);
         if (!insn_state)
                 return -ENOMEM;
 
         insn_stack = env->cfg.insn_stack = kvcalloc(insn_cnt, sizeof(int), GFP_KERNEL);
         if (!insn_stack) {
                 kvfree(insn_state);
                 return -ENOMEM;
         }
 
         insn_state[0] = DISCOVERED; /* mark 1st insn as discovered */
         insn_stack[0] = 0; /* 0 is the first instruction */
         env->cfg.cur_stack = 1;
 
 walk_cfg:
         while (env->cfg.cur_stack > 0) {
                 int t = insn_stack[env->cfg.cur_stack - 1];
 
                 ret = visit_insn(t, env);
                 switch (ret) {
                 case DONE_EXPLORING:
                         insn_state[t] = EXPLORED;
                         env->cfg.cur_stack--;
                         break;
                 case KEEP_EXPLORING:
                         break;
                 default:
                         if (ret > 0) {
                                 verbose(env, "visit_insn internal bug\n");
                                 ret = -EFAULT;
                         }
                         goto err_free;
                 }
         }
 
         if (env->cfg.cur_stack < 0) {
                 verbose(env, "pop stack internal bug\n");
                 ret = -EFAULT;
                 goto err_free;
         }
 
         if (env->exception_callback_subprog && !ex_done) {
                 ex_insn_beg = env->subprog_info[env->exception_callback_subprog].start;
 
                 insn_state[ex_insn_beg] = DISCOVERED;
                 insn_stack[0] = ex_insn_beg;
                 env->cfg.cur_stack = 1;
                 ex_done = true;
                 goto walk_cfg;
         }
 
         for (i = 0; i < insn_cnt; i++) {
                 struct bpf_insn *insn = &env->prog->insnsi[i];
 
                 if (insn_state[i] != EXPLORED) {
                         verbose(env, "unreachable insn %d\n", i);
                         ret = -EINVAL;
                         goto err_free;
                 }
                 if (bpf_is_ldimm64(insn)) {
                         if (insn_state[i + 1] != 0) {
                                 verbose(env, "jump into the middle of ldimm64 insn %d\n", i);
                                 ret = -EINVAL;
                                 goto err_free;
                         }
                         i++; /* skip second half of ldimm64 */
                 }
         }
         ret = 0; /* cfg looks good */
 
 err_free:
         kvfree(insn_state);
         kvfree(insn_stack);
         env->cfg.insn_state = env->cfg.insn_stack = NULL;
         return ret;
 }
 
 static int check_abnormal_return(struct bpf_verifier_env *env)
 {
         int i;
 
         for (i = 1; i < env->subprog_cnt; i++) {
                 if (env->subprog_info[i].has_ld_abs) {
                         verbose(env, "LD_ABS is not allowed in subprogs without BTF\n");
                         return -EINVAL;
                 }
                 if (env->subprog_info[i].has_tail_call) {
                         verbose(env, "tail_call is not allowed in subprogs without BTF\n");
                         return -EINVAL;
                 }
         }
         return 0;
 }
 
 /* The minimum supported BTF func info size */
 #define MIN_BPF_FUNCINFO_SIZE   8
 #define MAX_FUNCINFO_REC_SIZE   252
 
 static int check_btf_func_early(struct bpf_verifier_env *env,
                                 const union bpf_attr *attr,
                                 bpfptr_t uattr)
 {
         u32 krec_size = sizeof(struct bpf_func_info);
         const struct btf_type *type, *func_proto;
         u32 i, nfuncs, urec_size, min_size;
         struct bpf_func_info *krecord;
         struct bpf_prog *prog;
         const struct btf *btf;
         u32 prev_offset = 0;
         bpfptr_t urecord;
         int ret = -ENOMEM;
 
         nfuncs = attr->func_info_cnt;
         if (!nfuncs) {
                 if (check_abnormal_return(env))
                         return -EINVAL;
                 return 0;
         }
 
         urec_size = attr->func_info_rec_size;
         if (urec_size < MIN_BPF_FUNCINFO_SIZE ||
             urec_size > MAX_FUNCINFO_REC_SIZE ||
             urec_size % sizeof(u32)) {
                 verbose(env, "invalid func info rec size %u\n", urec_size);
                 return -EINVAL;
         }
 
         prog = env->prog;
         btf = prog->aux->btf;
 
         urecord = make_bpfptr(attr->func_info, uattr.is_kernel);
         min_size = min_t(u32, krec_size, urec_size);
 
         krecord = kvcalloc(nfuncs, krec_size, GFP_KERNEL | __GFP_NOWARN);
         if (!krecord)
                 return -ENOMEM;
 
         for (i = 0; i < nfuncs; i++) {
                 ret = bpf_check_uarg_tail_zero(urecord, krec_size, urec_size);
                 if (ret) {
                         if (ret == -E2BIG) {
                                 verbose(env, "nonzero tailing record in func info");
                                 /* set the size kernel expects so loader can zero
                                  * out the rest of the record.
                                  */
                                 if (copy_to_bpfptr_offset(uattr,
                                                           offsetof(union bpf_attr, func_info_rec_size),
                                                           &min_size, sizeof(min_size)))
                                         ret = -EFAULT;
                         }
                         goto err_free;
                 }
 
                 if (copy_from_bpfptr(&krecord[i], urecord, min_size)) {
                         ret = -EFAULT;
                         goto err_free;
                 }
 
                 /* check insn_off */
                 ret = -EINVAL;
                 if (i == 0) {
                         if (krecord[i].insn_off) {
                                 verbose(env,
                                         "nonzero insn_off %u for the first func info record",
                                         krecord[i].insn_off);
                                 goto err_free;
                         }
                 } else if (krecord[i].insn_off <= prev_offset) {
                         verbose(env,
                                 "same or smaller insn offset (%u) than previous func info record (%u)",
                                 krecord[i].insn_off, prev_offset);
                         goto err_free;
                 }
 
                 /* check type_id */
                 type = btf_type_by_id(btf, krecord[i].type_id);
                 if (!type || !btf_type_is_func(type)) {
                         verbose(env, "invalid type id %d in func info",
                                 krecord[i].type_id);
                         goto err_free;
                 }
 
                 func_proto = btf_type_by_id(btf, type->type);
                 if (unlikely(!func_proto || !btf_type_is_func_proto(func_proto)))
                         /* btf_func_check() already verified it during BTF load */
                         goto err_free;
 
                 prev_offset = krecord[i].insn_off;
                 bpfptr_add(&urecord, urec_size);
         }
 
         prog->aux->func_info = krecord;
         prog->aux->func_info_cnt = nfuncs;
         return 0;
 
 err_free:
         kvfree(krecord);
         return ret;
 }
 
 static int check_btf_func(struct bpf_verifier_env *env,
                           const union bpf_attr *attr,
                           bpfptr_t uattr)
 {
         const struct btf_type *type, *func_proto, *ret_type;
         u32 i, nfuncs, urec_size;
         struct bpf_func_info *krecord;
         struct bpf_func_info_aux *info_aux = NULL;
         struct bpf_prog *prog;
         const struct btf *btf;
         bpfptr_t urecord;
         bool scalar_return;
         int ret = -ENOMEM;
 
         nfuncs = attr->func_info_cnt;
         if (!nfuncs) {
                 if (check_abnormal_return(env))
                         return -EINVAL;
                 return 0;
         }
         if (nfuncs != env->subprog_cnt) {
                 verbose(env, "number of funcs in func_info doesn't match number of subprogs\n");
                 return -EINVAL;
         }
 
         urec_size = attr->func_info_rec_size;
 
         prog = env->prog;
         btf = prog->aux->btf;
 
         urecord = make_bpfptr(attr->func_info, uattr.is_kernel);
 
         krecord = prog->aux->func_info;
         info_aux = kcalloc(nfuncs, sizeof(*info_aux), GFP_KERNEL | __GFP_NOWARN);
         if (!info_aux)
                 return -ENOMEM;
 
         for (i = 0; i < nfuncs; i++) {
                 /* check insn_off */
                 ret = -EINVAL;
 
                 if (env->subprog_info[i].start != krecord[i].insn_off) {
                         verbose(env, "func_info BTF section doesn't match subprog layout in BPF program\n");
                         goto err_free;
                 }
 
                 /* Already checked type_id */
                 type = btf_type_by_id(btf, krecord[i].type_id);
                 info_aux[i].linkage = BTF_INFO_VLEN(type->info);
                 /* Already checked func_proto */
                 func_proto = btf_type_by_id(btf, type->type);
 
                 ret_type = btf_type_skip_modifiers(btf, func_proto->type, NULL);
                 scalar_return =
                         btf_type_is_small_int(ret_type) || btf_is_any_enum(ret_type);
                 if (i && !scalar_return && env->subprog_info[i].has_ld_abs) {
                         verbose(env, "LD_ABS is only allowed in functions that return 'int'.\n");
                         goto err_free;
                 }
                 if (i && !scalar_return && env->subprog_info[i].has_tail_call) {
                         verbose(env, "tail_call is only allowed in functions that return 'int'.\n");
                         goto err_free;
                 }
 
                 bpfptr_add(&urecord, urec_size);
         }
 
         prog->aux->func_info_aux = info_aux;
         return 0;
 
 err_free:
         kfree(info_aux);
         return ret;
 }
 
 static void adjust_btf_func(struct bpf_verifier_env *env)
 {
         struct bpf_prog_aux *aux = env->prog->aux;
         int i;
 
         if (!aux->func_info)
                 return;
 
         /* func_info is not available for hidden subprogs */
         for (i = 0; i < env->subprog_cnt - env->hidden_subprog_cnt; i++)
                 aux->func_info[i].insn_off = env->subprog_info[i].start;
 }
 
 #define MIN_BPF_LINEINFO_SIZE   offsetofend(struct bpf_line_info, line_col)
 #define MAX_LINEINFO_REC_SIZE   MAX_FUNCINFO_REC_SIZE
 
 static int check_btf_line(struct bpf_verifier_env *env,
                           const union bpf_attr *attr,
                           bpfptr_t uattr)
 {
         u32 i, s, nr_linfo, ncopy, expected_size, rec_size, prev_offset = 0;
         struct bpf_subprog_info *sub;
         struct bpf_line_info *linfo;
         struct bpf_prog *prog;
         const struct btf *btf;
         bpfptr_t ulinfo;
         int err;
 
         nr_linfo = attr->line_info_cnt;
         if (!nr_linfo)
                 return 0;
         if (nr_linfo > INT_MAX / sizeof(struct bpf_line_info))
                 return -EINVAL;
 
         rec_size = attr->line_info_rec_size;
         if (rec_size < MIN_BPF_LINEINFO_SIZE ||
             rec_size > MAX_LINEINFO_REC_SIZE ||
             rec_size & (sizeof(u32) - 1))
                 return -EINVAL;
 
         /* Need to zero it in case the userspace may
          * pass in a smaller bpf_line_info object.
          */
         linfo = kvcalloc(nr_linfo, sizeof(struct bpf_line_info),
                          GFP_KERNEL | __GFP_NOWARN);
         if (!linfo)
                 return -ENOMEM;
 
         prog = env->prog;
         btf = prog->aux->btf;
 
         s = 0;
         sub = env->subprog_info;
         ulinfo = make_bpfptr(attr->line_info, uattr.is_kernel);
         expected_size = sizeof(struct bpf_line_info);
         ncopy = min_t(u32, expected_size, rec_size);
         for (i = 0; i < nr_linfo; i++) {
                 err = bpf_check_uarg_tail_zero(ulinfo, expected_size, rec_size);
                 if (err) {
                         if (err == -E2BIG) {
                                 verbose(env, "nonzero tailing record in line_info");
                                 if (copy_to_bpfptr_offset(uattr,
                                                           offsetof(union bpf_attr, line_info_rec_size),
                                                           &expected_size, sizeof(expected_size)))
                                         err = -EFAULT;
                         }
                         goto err_free;
                 }
 
                 if (copy_from_bpfptr(&linfo[i], ulinfo, ncopy)) {
                         err = -EFAULT;
                         goto err_free;
                 }
 
                 /*
                  * Check insn_off to ensure
                  * 1) strictly increasing AND
                  * 2) bounded by prog->len
                  *
                  * The linfo[0].insn_off == 0 check logically falls into
                  * the later "missing bpf_line_info for func..." case
                  * because the first linfo[0].insn_off must be the
                  * first sub also and the first sub must have
                  * subprog_info[0].start == 0.
                  */
                 if ((i && linfo[i].insn_off <= prev_offset) ||
                     linfo[i].insn_off >= prog->len) {
                         verbose(env, "Invalid line_info[%u].insn_off:%u (prev_offset:%u prog->len:%u)\n",
                                 i, linfo[i].insn_off, prev_offset,
                                 prog->len);
                         err = -EINVAL;
                         goto err_free;
                 }
 
                 if (!prog->insnsi[linfo[i].insn_off].code) {
                         verbose(env,
                                 "Invalid insn code at line_info[%u].insn_off\n",
                                 i);
                         err = -EINVAL;
                         goto err_free;
                 }
 
                 if (!btf_name_by_offset(btf, linfo[i].line_off) ||
                     !btf_name_by_offset(btf, linfo[i].file_name_off)) {
                         verbose(env, "Invalid line_info[%u].line_off or .file_name_off\n", i);
                         err = -EINVAL;
                         goto err_free;
                 }
 
                 if (s != env->subprog_cnt) {
                         if (linfo[i].insn_off == sub[s].start) {
                                 sub[s].linfo_idx = i;
                                 s++;
                         } else if (sub[s].start < linfo[i].insn_off) {
                                 verbose(env, "missing bpf_line_info for func#%u\n", s);
                                 err = -EINVAL;
                                 goto err_free;
                         }
                 }
 
                 prev_offset = linfo[i].insn_off;
                 bpfptr_add(&ulinfo, rec_size);
         }
 
         if (s != env->subprog_cnt) {
                 verbose(env, "missing bpf_line_info for %u funcs starting from func#%u\n",
                         env->subprog_cnt - s, s);
                 err = -EINVAL;
                 goto err_free;
         }
 
         prog->aux->linfo = linfo;
         prog->aux->nr_linfo = nr_linfo;
 
         return 0;
 
 err_free:
         kvfree(linfo);
         return err;
 }
 
 #define MIN_CORE_RELO_SIZE      sizeof(struct bpf_core_relo)
 #define MAX_CORE_RELO_SIZE      MAX_FUNCINFO_REC_SIZE
 
 static int check_core_relo(struct bpf_verifier_env *env,
                            const union bpf_attr *attr,
                            bpfptr_t uattr)
 {
         u32 i, nr_core_relo, ncopy, expected_size, rec_size;
         struct bpf_core_relo core_relo = {};
         struct bpf_prog *prog = env->prog;
         const struct btf *btf = prog->aux->btf;
         struct bpf_core_ctx ctx = {
                 .log = &env->log,
                 .btf = btf,
         };
         bpfptr_t u_core_relo;
         int err;
 
         nr_core_relo = attr->core_relo_cnt;
         if (!nr_core_relo)
                 return 0;
         if (nr_core_relo > INT_MAX / sizeof(struct bpf_core_relo))
                 return -EINVAL;
 
         rec_size = attr->core_relo_rec_size;
         if (rec_size < MIN_CORE_RELO_SIZE ||
             rec_size > MAX_CORE_RELO_SIZE ||
             rec_size % sizeof(u32))
                 return -EINVAL;
 
         u_core_relo = make_bpfptr(attr->core_relos, uattr.is_kernel);
         expected_size = sizeof(struct bpf_core_relo);
         ncopy = min_t(u32, expected_size, rec_size);
 
         /* Unlike func_info and line_info, copy and apply each CO-RE
          * relocation record one at a time.
          */
         for (i = 0; i < nr_core_relo; i++) {
                 /* future proofing when sizeof(bpf_core_relo) changes */
                 err = bpf_check_uarg_tail_zero(u_core_relo, expected_size, rec_size);
                 if (err) {
                         if (err == -E2BIG) {
                                 verbose(env, "nonzero tailing record in core_relo");
                                 if (copy_to_bpfptr_offset(uattr,
                                                           offsetof(union bpf_attr, core_relo_rec_size),
                                                           &expected_size, sizeof(expected_size)))
                                         err = -EFAULT;
                         }
                         break;
                 }
 
                 if (copy_from_bpfptr(&core_relo, u_core_relo, ncopy)) {
                         err = -EFAULT;
                         break;
                 }
 
                 if (core_relo.insn_off % 8 || core_relo.insn_off / 8 >= prog->len) {
                         verbose(env, "Invalid core_relo[%u].insn_off:%u prog->len:%u\n",
                                 i, core_relo.insn_off, prog->len);
                         err = -EINVAL;
                         break;
                 }
 
                 err = bpf_core_apply(&ctx, &core_relo, i,
                                      &prog->insnsi[core_relo.insn_off / 8]);
                 if (err)
                         break;
                 bpfptr_add(&u_core_relo, rec_size);
         }
         return err;
 }
 
 static int check_btf_info_early(struct bpf_verifier_env *env,
                                 const union bpf_attr *attr,
                                 bpfptr_t uattr)
 {
         struct btf *btf;
         int err;
 
         if (!attr->func_info_cnt && !attr->line_info_cnt) {
                 if (check_abnormal_return(env))
                         return -EINVAL;
                 return 0;
         }
 
         btf = btf_get_by_fd(attr->prog_btf_fd);
         if (IS_ERR(btf))
                 return PTR_ERR(btf);
         if (btf_is_kernel(btf)) {
                 btf_put(btf);
                 return -EACCES;
         }
         env->prog->aux->btf = btf;
 
         err = check_btf_func_early(env, attr, uattr);
         if (err)
                 return err;
         return 0;
 }
 
 static int check_btf_info(struct bpf_verifier_env *env,
                           const union bpf_attr *attr,
                           bpfptr_t uattr)
 {
         int err;
 
         if (!attr->func_info_cnt && !attr->line_info_cnt) {
                 if (check_abnormal_return(env))
                         return -EINVAL;
                 return 0;
         }
 
         err = check_btf_func(env, attr, uattr);
         if (err)
                 return err;
 
         err = check_btf_line(env, attr, uattr);
         if (err)
                 return err;
 
         err = check_core_relo(env, attr, uattr);
         if (err)
                 return err;
 
         return 0;
 }
 
 /* check %cur's range satisfies %old's */
 static bool range_within(const struct bpf_reg_state *old,
                          const struct bpf_reg_state *cur)
 {
         return old->umin_value <= cur->umin_value &&
                old->umax_value >= cur->umax_value &&
                old->smin_value <= cur->smin_value &&
                old->smax_value >= cur->smax_value &&
                old->u32_min_value <= cur->u32_min_value &&
                old->u32_max_value >= cur->u32_max_value &&
                old->s32_min_value <= cur->s32_min_value &&
                old->s32_max_value >= cur->s32_max_value;
 }
 
 /* If in the old state two registers had the same id, then they need to have
  * the same id in the new state as well.  But that id could be different from
  * the old state, so we need to track the mapping from old to new ids.
  * Once we have seen that, say, a reg with old id 5 had new id 9, any subsequent
  * regs with old id 5 must also have new id 9 for the new state to be safe.  But
  * regs with a different old id could still have new id 9, we don't care about
  * that.
  * So we look through our idmap to see if this old id has been seen before.  If
  * so, we require the new id to match; otherwise, we add the id pair to the map.
  */
 static bool check_ids(u32 old_id, u32 cur_id, struct bpf_idmap *idmap)
 {
         struct bpf_id_pair *map = idmap->map;
         unsigned int i;
 
         /* either both IDs should be set or both should be zero */
         if (!!old_id != !!cur_id)
                 return false;
 
         if (old_id == 0) /* cur_id == 0 as well */
                 return true;
 
         for (i = 0; i < BPF_ID_MAP_SIZE; i++) {
                 if (!map[i].old) {
                         /* Reached an empty slot; haven't seen this id before */
                         map[i].old = old_id;
                         map[i].cur = cur_id;
                         return true;
                 }
                 if (map[i].old == old_id)
                         return map[i].cur == cur_id;
                 if (map[i].cur == cur_id)
                         return false;
         }
         /* We ran out of idmap slots, which should be impossible */
         WARN_ON_ONCE(1);
         return false;
 }
 
 /* Similar to check_ids(), but allocate a unique temporary ID
  * for 'old_id' or 'cur_id' of zero.
  * This makes pairs like '0 vs unique ID', 'unique ID vs 0' valid.
  */
 static bool check_scalar_ids(u32 old_id, u32 cur_id, struct bpf_idmap *idmap)
 {
         old_id = old_id ? old_id : ++idmap->tmp_id_gen;
         cur_id = cur_id ? cur_id : ++idmap->tmp_id_gen;
 
         return check_ids(old_id, cur_id, idmap);
 }
 
 static void clean_func_state(struct bpf_verifier_env *env,
                              struct bpf_func_state *st)
 {
         enum bpf_reg_liveness live;
         int i, j;
 
         for (i = 0; i < BPF_REG_FP; i++) {
                 live = st->regs[i].live;
                 /* liveness must not touch this register anymore */
                 st->regs[i].live |= REG_LIVE_DONE;
                 if (!(live & REG_LIVE_READ))
                         /* since the register is unused, clear its state
                          * to make further comparison simpler
                          */
                         __mark_reg_not_init(env, &st->regs[i]);
         }
 
         for (i = 0; i < st->allocated_stack / BPF_REG_SIZE; i++) {
                 live = st->stack[i].spilled_ptr.live;
                 /* liveness must not touch this stack slot anymore */
                 st->stack[i].spilled_ptr.live |= REG_LIVE_DONE;
                 if (!(live & REG_LIVE_READ)) {
                         __mark_reg_not_init(env, &st->stack[i].spilled_ptr);
                         for (j = 0; j < BPF_REG_SIZE; j++)
                                 st->stack[i].slot_type[j] = STACK_INVALID;
                 }
         }
 }
 
 static void clean_verifier_state(struct bpf_verifier_env *env,
                                  struct bpf_verifier_state *st)
 {
         int i;
 
         if (st->frame[0]->regs[0].live & REG_LIVE_DONE)
                 /* all regs in this state in all frames were already marked */
                 return;
 
         for (i = 0; i <= st->curframe; i++)
                 clean_func_state(env, st->frame[i]);
 }
 
 /* the parentage chains form a tree.
  * the verifier states are added to state lists at given insn and
  * pushed into state stack for future exploration.
  * when the verifier reaches bpf_exit insn some of the verifer states
  * stored in the state lists have their final liveness state already,
  * but a lot of states will get revised from liveness point of view when
  * the verifier explores other branches.
  * Example:
  * 1: r0 = 1
  * 2: if r1 == 100 goto pc+1
  * 3: r0 = 2
  * 4: exit
  * when the verifier reaches exit insn the register r0 in the state list of
  * insn 2 will be seen as !REG_LIVE_READ. Then the verifier pops the other_branch
  * of insn 2 and goes exploring further. At the insn 4 it will walk the
  * parentage chain from insn 4 into insn 2 and will mark r0 as REG_LIVE_READ.
  *
  * Since the verifier pushes the branch states as it sees them while exploring
  * the program the condition of walking the branch instruction for the second
  * time means that all states below this branch were already explored and
  * their final liveness marks are already propagated.
  * Hence when the verifier completes the search of state list in is_state_visited()
  * we can call this clean_live_states() function to mark all liveness states
  * as REG_LIVE_DONE to indicate that 'parent' pointers of 'struct bpf_reg_state'
  * will not be used.
  * This function also clears the registers and stack for states that !READ
  * to simplify state merging.
  *
  * Important note here that walking the same branch instruction in the callee
  * doesn't meant that the states are DONE. The verifier has to compare
  * the callsites
  */
 static void clean_live_states(struct bpf_verifier_env *env, int insn,
                               struct bpf_verifier_state *cur)
 {
         struct bpf_verifier_state_list *sl;
 
         sl = *explored_state(env, insn);
         while (sl) {
                 if (sl->state.branches)
                         goto next;
                 if (sl->state.insn_idx != insn ||
                     !same_callsites(&sl->state, cur))
                         goto next;
                 clean_verifier_state(env, &sl->state);
 next:
                 sl = sl->next;
         }
 }
 
 static bool regs_exact(const struct bpf_reg_state *rold,
                        const struct bpf_reg_state *rcur,
                        struct bpf_idmap *idmap)
 {
         return memcmp(rold, rcur, offsetof(struct bpf_reg_state, id)) == 0 &&
                check_ids(rold->id, rcur->id, idmap) &&
                check_ids(rold->ref_obj_id, rcur->ref_obj_id, idmap);
 }
 
 enum exact_level {
         NOT_EXACT,
         EXACT,
         RANGE_WITHIN
 };
 
 /* Returns true if (rold safe implies rcur safe) */
 static bool regsafe(struct bpf_verifier_env *env, struct bpf_reg_state *rold,
                     struct bpf_reg_state *rcur, struct bpf_idmap *idmap,
                     enum exact_level exact)
 {
         if (exact == EXACT)
                 return regs_exact(rold, rcur, idmap);
 
         if (!(rold->live & REG_LIVE_READ) && exact == NOT_EXACT)
                 /* explored state didn't use this */
                 return true;
         if (rold->type == NOT_INIT) {
                 if (exact == NOT_EXACT || rcur->type == NOT_INIT)
                         /* explored state can't have used this */
                         return true;
         }
 
         /* Enforce that register types have to match exactly, including their
          * modifiers (like PTR_MAYBE_NULL, MEM_RDONLY, etc), as a general
          * rule.
          *
          * One can make a point that using a pointer register as unbounded
          * SCALAR would be technically acceptable, but this could lead to
          * pointer leaks because scalars are allowed to leak while pointers
          * are not. We could make this safe in special cases if root is
          * calling us, but it's probably not worth the hassle.
          *
          * Also, register types that are *not* MAYBE_NULL could technically be
          * safe to use as their MAYBE_NULL variants (e.g., PTR_TO_MAP_VALUE
          * is safe to be used as PTR_TO_MAP_VALUE_OR_NULL, provided both point
          * to the same map).
          * However, if the old MAYBE_NULL register then got NULL checked,
          * doing so could have affected others with the same id, and we can't
          * check for that because we lost the id when we converted to
          * a non-MAYBE_NULL variant.
          * So, as a general rule we don't allow mixing MAYBE_NULL and
          * non-MAYBE_NULL registers as well.
          */
         if (rold->type != rcur->type)
                 return false;
 
         switch (base_type(rold->type)) {
         case SCALAR_VALUE:
                 if (env->explore_alu_limits) {
                         /* explore_alu_limits disables tnum_in() and range_within()
                          * logic and requires everything to be strict
                          */
                         return memcmp(rold, rcur, offsetof(struct bpf_reg_state, id)) == 0 &&
                                check_scalar_ids(rold->id, rcur->id, idmap);
                 }
                 if (!rold->precise && exact == NOT_EXACT)
                         return true;
                 if ((rold->id & BPF_ADD_CONST) != (rcur->id & BPF_ADD_CONST))
                         return false;
                 if ((rold->id & BPF_ADD_CONST) && (rold->off != rcur->off))
                         return false;
                 /* Why check_ids() for scalar registers?
                  *
                  * Consider the following BPF code:
                  *   1: r6 = ... unbound scalar, ID=a ...
                  *   2: r7 = ... unbound scalar, ID=b ...
                  *   3: if (r6 > r7) goto +1
                  *   4: r6 = r7
                  *   5: if (r6 > X) goto ...
                  *   6: ... memory operation using r7 ...
                  *
                  * First verification path is [1-6]:
                  * - at (4) same bpf_reg_state::id (b) would be assigned to r6 and r7;
                  * - at (5) r6 would be marked <= X, find_equal_scalars() would also mark
                  *   r7 <= X, because r6 and r7 share same id.
                  * Next verification path is [1-4, 6].
                  *
                  * Instruction (6) would be reached in two states:
                  *   I.  r6{.id=b}, r7{.id=b} via path 1-6;
                  *   II. r6{.id=a}, r7{.id=b} via path 1-4, 6.
                  *
                  * Use check_ids() to distinguish these states.
                  * ---
                  * Also verify that new value satisfies old value range knowledge.
                  */
                 return range_within(rold, rcur) &&
                        tnum_in(rold->var_off, rcur->var_off) &&
                        check_scalar_ids(rold->id, rcur->id, idmap);
         case PTR_TO_MAP_KEY:
         case PTR_TO_MAP_VALUE:
         case PTR_TO_MEM:
         case PTR_TO_BUF:
         case PTR_TO_TP_BUFFER:
                 /* If the new min/max/var_off satisfy the old ones and
                  * everything else matches, we are OK.
                  */
                 return memcmp(rold, rcur, offsetof(struct bpf_reg_state, var_off)) == 0 &&
                        range_within(rold, rcur) &&
                        tnum_in(rold->var_off, rcur->var_off) &&
                        check_ids(rold->id, rcur->id, idmap) &&
                        check_ids(rold->ref_obj_id, rcur->ref_obj_id, idmap);
         case PTR_TO_PACKET_META:
         case PTR_TO_PACKET:
                 /* We must have at least as much range as the old ptr
                  * did, so that any accesses which were safe before are
                  * still safe.  This is true even if old range < old off,
                  * since someone could have accessed through (ptr - k), or
                  * even done ptr -= k in a register, to get a safe access.
                  */
                 if (rold->range > rcur->range)
                         return false;
                 /* If the offsets don't match, we can't trust our alignment;
                  * nor can we be sure that we won't fall out of range.
                  */
                 if (rold->off != rcur->off)
                         return false;
                 /* id relations must be preserved */
                 if (!check_ids(rold->id, rcur->id, idmap))
                         return false;
                 /* new val must satisfy old val knowledge */
                 return range_within(rold, rcur) &&
                        tnum_in(rold->var_off, rcur->var_off);
         case PTR_TO_STACK:
                 /* two stack pointers are equal only if they're pointing to
                  * the same stack frame, since fp-8 in foo != fp-8 in bar
                  */
                 return regs_exact(rold, rcur, idmap) && rold->frameno == rcur->frameno;
         case PTR_TO_ARENA:
                 return true;
         default:
                 return regs_exact(rold, rcur, idmap);
         }
 }
 
 static struct bpf_reg_state unbound_reg;
 
 static __init int unbound_reg_init(void)
 {
         __mark_reg_unknown_imprecise(&unbound_reg);
         unbound_reg.live |= REG_LIVE_READ;
         return 0;
 }
 late_initcall(unbound_reg_init);
 
 static bool is_stack_all_misc(struct bpf_verifier_env *env,
                               struct bpf_stack_state *stack)
 {
         u32 i;
 
         for (i = 0; i < ARRAY_SIZE(stack->slot_type); ++i) {
                 if ((stack->slot_type[i] == STACK_MISC) ||
                     (stack->slot_type[i] == STACK_INVALID && env->allow_uninit_stack))
                         continue;
                 return false;
         }
 
         return true;
 }
 
 static struct bpf_reg_state *scalar_reg_for_stack(struct bpf_verifier_env *env,
                                                   struct bpf_stack_state *stack)
 {
         if (is_spilled_scalar_reg64(stack))
                 return &stack->spilled_ptr;
 
         if (is_stack_all_misc(env, stack))
                 return &unbound_reg;
 
         return NULL;
 }
 
 static bool stacksafe(struct bpf_verifier_env *env, struct bpf_func_state *old,
                       struct bpf_func_state *cur, struct bpf_idmap *idmap,
                       enum exact_level exact)
 {
         int i, spi;
 
         /* walk slots of the explored stack and ignore any additional
          * slots in the current stack, since explored(safe) state
          * didn't use them
          */
         for (i = 0; i < old->allocated_stack; i++) {
                 struct bpf_reg_state *old_reg, *cur_reg;
 
                 spi = i / BPF_REG_SIZE;
 
                 if (exact != NOT_EXACT &&
                     (i >= cur->allocated_stack ||
                      old->stack[spi].slot_type[i % BPF_REG_SIZE] !=
                      cur->stack[spi].slot_type[i % BPF_REG_SIZE]))
                         return false;
 
                 if (!(old->stack[spi].spilled_ptr.live & REG_LIVE_READ)
                     && exact == NOT_EXACT) {
                         i += BPF_REG_SIZE - 1;
                         /* explored state didn't use this */
                         continue;
                 }
 
                 if (old->stack[spi].slot_type[i % BPF_REG_SIZE] == STACK_INVALID)
                         continue;
 
                 if (env->allow_uninit_stack &&
                     old->stack[spi].slot_type[i % BPF_REG_SIZE] == STACK_MISC)
                         continue;
 
                 /* explored stack has more populated slots than current stack
                  * and these slots were used
                  */
                 if (i >= cur->allocated_stack)
                         return false;
 
                 /* 64-bit scalar spill vs all slots MISC and vice versa.
                  * Load from all slots MISC produces unbound scalar.
                  * Construct a fake register for such stack and call
                  * regsafe() to ensure scalar ids are compared.
                  */
                 old_reg = scalar_reg_for_stack(env, &old->stack[spi]);
                 cur_reg = scalar_reg_for_stack(env, &cur->stack[spi]);
                 if (old_reg && cur_reg) {
                         if (!regsafe(env, old_reg, cur_reg, idmap, exact))
                                 return false;
                         i += BPF_REG_SIZE - 1;
                         continue;
                 }
 
                 /* if old state was safe with misc data in the stack
                  * it will be safe with zero-initialized stack.
                  * The opposite is not true
                  */
                 if (old->stack[spi].slot_type[i % BPF_REG_SIZE] == STACK_MISC &&
                     cur->stack[spi].slot_type[i % BPF_REG_SIZE] == STACK_ZERO)
                         continue;
                 if (old->stack[spi].slot_type[i % BPF_REG_SIZE] !=
                     cur->stack[spi].slot_type[i % BPF_REG_SIZE])
                         /* Ex: old explored (safe) state has STACK_SPILL in
                          * this stack slot, but current has STACK_MISC ->
                          * this verifier states are not equivalent,
                          * return false to continue verification of this path
                          */
                         return false;
                 if (i % BPF_REG_SIZE != BPF_REG_SIZE - 1)
                         continue;
                 /* Both old and cur are having same slot_type */
                 switch (old->stack[spi].slot_type[BPF_REG_SIZE - 1]) {
                 case STACK_SPILL:
                         /* when explored and current stack slot are both storing
                          * spilled registers, check that stored pointers types
                          * are the same as well.
                          * Ex: explored safe path could have stored
                          * (bpf_reg_state) {.type = PTR_TO_STACK, .off = -8}
                          * but current path has stored:
                          * (bpf_reg_state) {.type = PTR_TO_STACK, .off = -16}
                          * such verifier states are not equivalent.
                          * return false to continue verification of this path
                          */
                         if (!regsafe(env, &old->stack[spi].spilled_ptr,
                                      &cur->stack[spi].spilled_ptr, idmap, exact))
                                 return false;
                         break;
                 case STACK_DYNPTR:
                         old_reg = &old->stack[spi].spilled_ptr;
                         cur_reg = &cur->stack[spi].spilled_ptr;
                         if (old_reg->dynptr.type != cur_reg->dynptr.type ||
                             old_reg->dynptr.first_slot != cur_reg->dynptr.first_slot ||
                             !check_ids(old_reg->ref_obj_id, cur_reg->ref_obj_id, idmap))
                                 return false;
                         break;
                 case STACK_ITER:
                         old_reg = &old->stack[spi].spilled_ptr;
                         cur_reg = &cur->stack[spi].spilled_ptr;
                         /* iter.depth is not compared between states as it
                          * doesn't matter for correctness and would otherwise
                          * prevent convergence; we maintain it only to prevent
                          * infinite loop check triggering, see
                          * iter_active_depths_differ()
                          */
                         if (old_reg->iter.btf != cur_reg->iter.btf ||
                             old_reg->iter.btf_id != cur_reg->iter.btf_id ||
                             old_reg->iter.state != cur_reg->iter.state ||
                             /* ignore {old_reg,cur_reg}->iter.depth, see above */
                             !check_ids(old_reg->ref_obj_id, cur_reg->ref_obj_id, idmap))
                                 return false;
                         break;
                 case STACK_MISC:
                 case STACK_ZERO:
                 case STACK_INVALID:
                         continue;
                 /* Ensure that new unhandled slot types return false by default */
                 default:
                         return false;
                 }
         }
         return true;
 }
 
 static bool refsafe(struct bpf_func_state *old, struct bpf_func_state *cur,
                     struct bpf_idmap *idmap)
 {
         int i;
 
         if (old->acquired_refs != cur->acquired_refs)
                 return false;
 
         for (i = 0; i < old->acquired_refs; i++) {
                 if (!check_ids(old->refs[i].id, cur->refs[i].id, idmap))
                         return false;
         }
 
         return true;
 }
 
 /* compare two verifier states
  *
  * all states stored in state_list are known to be valid, since
  * verifier reached 'bpf_exit' instruction through them
  *
  * this function is called when verifier exploring different branches of
  * execution popped from the state stack. If it sees an old state that has
  * more strict register state and more strict stack state then this execution
  * branch doesn't need to be explored further, since verifier already
  * concluded that more strict state leads to valid finish.
  *
  * Therefore two states are equivalent if register state is more conservative
  * and explored stack state is more conservative than the current one.
  * Example:
  *       explored                   current
  * (slot1=INV slot2=MISC) == (slot1=MISC slot2=MISC)
  * (slot1=MISC slot2=MISC) != (slot1=INV slot2=MISC)
  *
  * In other words if current stack state (one being explored) has more
  * valid slots than old one that already passed validation, it means
  * the verifier can stop exploring and conclude that current state is valid too
  *
  * Similarly with registers. If explored state has register type as invalid
  * whereas register type in current state is meaningful, it means that
  * the current state will reach 'bpf_exit' instruction safely
  */
 static bool func_states_equal(struct bpf_verifier_env *env, struct bpf_func_state *old,
                               struct bpf_func_state *cur, enum exact_level exact)
 {
         int i;
 
         if (old->callback_depth > cur->callback_depth)
                 return false;
 
         for (i = 0; i < MAX_BPF_REG; i++)
                 if (!regsafe(env, &old->regs[i], &cur->regs[i],
                              &env->idmap_scratch, exact))
                         return false;
 
         if (!stacksafe(env, old, cur, &env->idmap_scratch, exact))
                 return false;
 
         if (!refsafe(old, cur, &env->idmap_scratch))
                 return false;
 
         return true;
 }
 
 static void reset_idmap_scratch(struct bpf_verifier_env *env)
 {
         env->idmap_scratch.tmp_id_gen = env->id_gen;
         memset(&env->idmap_scratch.map, 0, sizeof(env->idmap_scratch.map));
 }
 
 static bool states_equal(struct bpf_verifier_env *env,
                          struct bpf_verifier_state *old,
                          struct bpf_verifier_state *cur,
                          enum exact_level exact)
 {
         int i;
 
         if (old->curframe != cur->curframe)
                 return false;
 
         reset_idmap_scratch(env);
 
         /* Verification state from speculative execution simulation
          * must never prune a non-speculative execution one.
          */
         if (old->speculative && !cur->speculative)
                 return false;
 
         if (old->active_lock.ptr != cur->active_lock.ptr)
                 return false;
 
         /* Old and cur active_lock's have to be either both present
          * or both absent.
          */
         if (!!old->active_lock.id != !!cur->active_lock.id)
                 return false;
 
         if (old->active_lock.id &&
             !check_ids(old->active_lock.id, cur->active_lock.id, &env->idmap_scratch))
                 return false;
 
         if (old->active_rcu_lock != cur->active_rcu_lock)
                 return false;
 
         if (old->active_preempt_lock != cur->active_preempt_lock)
                 return false;
 
         if (old->in_sleepable != cur->in_sleepable)
                 return false;
 
         /* for states to be equal callsites have to be the same
          * and all frame states need to be equivalent
          */
         for (i = 0; i <= old->curframe; i++) {
                 if (old->frame[i]->callsite != cur->frame[i]->callsite)
                         return false;
                 if (!func_states_equal(env, old->frame[i], cur->frame[i], exact))
                         return false;
         }
         return true;
 }
 
 /* Return 0 if no propagation happened. Return negative error code if error
  * happened. Otherwise, return the propagated bit.
  */
 static int propagate_liveness_reg(struct bpf_verifier_env *env,
                                   struct bpf_reg_state *reg,
                                   struct bpf_reg_state *parent_reg)
 {
         u8 parent_flag = parent_reg->live & REG_LIVE_READ;
         u8 flag = reg->live & REG_LIVE_READ;
         int err;
 
         /* When comes here, read flags of PARENT_REG or REG could be any of
          * REG_LIVE_READ64, REG_LIVE_READ32, REG_LIVE_NONE. There is no need
          * of propagation if PARENT_REG has strongest REG_LIVE_READ64.
          */
         if (parent_flag == REG_LIVE_READ64 ||
             /* Or if there is no read flag from REG. */
             !flag ||
             /* Or if the read flag from REG is the same as PARENT_REG. */
             parent_flag == flag)
                 return 0;
 
         err = mark_reg_read(env, reg, parent_reg, flag);
         if (err)
                 return err;
 
         return flag;
 }
 
 /* A write screens off any subsequent reads; but write marks come from the
  * straight-line code between a state and its parent.  When we arrive at an
  * equivalent state (jump target or such) we didn't arrive by the straight-line
  * code, so read marks in the state must propagate to the parent regardless
  * of the state's write marks. That's what 'parent == state->parent' comparison
  * in mark_reg_read() is for.
  */
 static int propagate_liveness(struct bpf_verifier_env *env,
                               const struct bpf_verifier_state *vstate,
                               struct bpf_verifier_state *vparent)
 {
         struct bpf_reg_state *state_reg, *parent_reg;
         struct bpf_func_state *state, *parent;
         int i, frame, err = 0;
 
         if (vparent->curframe != vstate->curframe) {
                 WARN(1, "propagate_live: parent frame %d current frame %d\n",
                      vparent->curframe, vstate->curframe);
                 return -EFAULT;
         }
         /* Propagate read liveness of registers... */
         BUILD_BUG_ON(BPF_REG_FP + 1 != MAX_BPF_REG);
         for (frame = 0; frame <= vstate->curframe; frame++) {
                 parent = vparent->frame[frame];
                 state = vstate->frame[frame];
                 parent_reg = parent->regs;
                 state_reg = state->regs;
                 /* We don't need to worry about FP liveness, it's read-only */
                 for (i = frame < vstate->curframe ? BPF_REG_6 : 0; i < BPF_REG_FP; i++) {
                         err = propagate_liveness_reg(env, &state_reg[i],
                                                      &parent_reg[i]);
                         if (err < 0)
                                 return err;
                         if (err == REG_LIVE_READ64)
                                 mark_insn_zext(env, &parent_reg[i]);
                 }
 
                 /* Propagate stack slots. */
                 for (i = 0; i < state->allocated_stack / BPF_REG_SIZE &&
                             i < parent->allocated_stack / BPF_REG_SIZE; i++) {
                         parent_reg = &parent->stack[i].spilled_ptr;
                         state_reg = &state->stack[i].spilled_ptr;
                         err = propagate_liveness_reg(env, state_reg,
                                                      parent_reg);
                         if (err < 0)
                                 return err;
                 }
         }
         return 0;
 }
 
 /* find precise scalars in the previous equivalent state and
  * propagate them into the current state
  */
 static int propagate_precision(struct bpf_verifier_env *env,
                                const struct bpf_verifier_state *old)
 {
         struct bpf_reg_state *state_reg;
         struct bpf_func_state *state;
         int i, err = 0, fr;
         bool first;
 
         for (fr = old->curframe; fr >= 0; fr--) {
                 state = old->frame[fr];
                 state_reg = state->regs;
                 first = true;
                 for (i = 0; i < BPF_REG_FP; i++, state_reg++) {
                         if (state_reg->type != SCALAR_VALUE ||
                             !state_reg->precise ||
                             !(state_reg->live & REG_LIVE_READ))
                                 continue;
                         if (env->log.level & BPF_LOG_LEVEL2) {
                                 if (first)
                                         verbose(env, "frame %d: propagating r%d", fr, i);
                                 else
                                         verbose(env, ",r%d", i);
                         }
                         bt_set_frame_reg(&env->bt, fr, i);
                         first = false;
                 }
 
                 for (i = 0; i < state->allocated_stack / BPF_REG_SIZE; i++) {
                         if (!is_spilled_reg(&state->stack[i]))
                                 continue;
                         state_reg = &state->stack[i].spilled_ptr;
                         if (state_reg->type != SCALAR_VALUE ||
                             !state_reg->precise ||
                             !(state_reg->live & REG_LIVE_READ))
                                 continue;
                         if (env->log.level & BPF_LOG_LEVEL2) {
                                 if (first)
                                         verbose(env, "frame %d: propagating fp%d",
                                                 fr, (-i - 1) * BPF_REG_SIZE);
                                 else
                                         verbose(env, ",fp%d", (-i - 1) * BPF_REG_SIZE);
                         }
                         bt_set_frame_slot(&env->bt, fr, i);
                         first = false;
                 }
                 if (!first)
                         verbose(env, "\n");
         }
 
         err = mark_chain_precision_batch(env);
         if (err < 0)
                 return err;
 
         return 0;
 }
 
 static bool states_maybe_looping(struct bpf_verifier_state *old,
                                  struct bpf_verifier_state *cur)
 {
         struct bpf_func_state *fold, *fcur;
         int i, fr = cur->curframe;
 
         if (old->curframe != fr)
                 return false;
 
         fold = old->frame[fr];
         fcur = cur->frame[fr];
         for (i = 0; i < MAX_BPF_REG; i++)
                 if (memcmp(&fold->regs[i], &fcur->regs[i],
                            offsetof(struct bpf_reg_state, parent)))
                         return false;
         return true;
 }
 
 static bool is_iter_next_insn(struct bpf_verifier_env *env, int insn_idx)
 {
         return env->insn_aux_data[insn_idx].is_iter_next;
 }
 
 /* is_state_visited() handles iter_next() (see process_iter_next_call() for
  * terminology) calls specially: as opposed to bounded BPF loops, it *expects*
  * states to match, which otherwise would look like an infinite loop. So while
  * iter_next() calls are taken care of, we still need to be careful and
  * prevent erroneous and too eager declaration of "ininite loop", when
  * iterators are involved.
  *
  * Here's a situation in pseudo-BPF assembly form:
  *
  *   0: again:                          ; set up iter_next() call args
  *   1:   r1 = &it                      ; <CHECKPOINT HERE>
  *   2:   call bpf_iter_num_next        ; this is iter_next() call
  *   3:   if r0 == 0 goto done
  *   4:   ... something useful here ...
  *   5:   goto again                    ; another iteration
  *   6: done:
  *   7:   r1 = &it
  *   8:   call bpf_iter_num_destroy     ; clean up iter state
  *   9:   exit
  *
  * This is a typical loop. Let's assume that we have a prune point at 1:,
  * before we get to `call bpf_iter_num_next` (e.g., because of that `goto
  * again`, assuming other heuristics don't get in a way).
  *
  * When we first time come to 1:, let's say we have some state X. We proceed
  * to 2:, fork states, enqueue ACTIVE, validate NULL case successfully, exit.
  * Now we come back to validate that forked ACTIVE state. We proceed through
  * 3-5, come to goto, jump to 1:. Let's assume our state didn't change, so we
  * are converging. But the problem is that we don't know that yet, as this
  * convergence has to happen at iter_next() call site only. So if nothing is
  * done, at 1: verifier will use bounded loop logic and declare infinite
  * looping (and would be *technically* correct, if not for iterator's
  * "eventual sticky NULL" contract, see process_iter_next_call()). But we
  * don't want that. So what we do in process_iter_next_call() when we go on
  * another ACTIVE iteration, we bump slot->iter.depth, to mark that it's
  * a different iteration. So when we suspect an infinite loop, we additionally
  * check if any of the *ACTIVE* iterator states depths differ. If yes, we
  * pretend we are not looping and wait for next iter_next() call.
  *
  * This only applies to ACTIVE state. In DRAINED state we don't expect to
  * loop, because that would actually mean infinite loop, as DRAINED state is
  * "sticky", and so we'll keep returning into the same instruction with the
  * same state (at least in one of possible code paths).
  *
  * This approach allows to keep infinite loop heuristic even in the face of
  * active iterator. E.g., C snippet below is and will be detected as
  * inifintely looping:
  *
  *   struct bpf_iter_num it;
  *   int *p, x;
  *
  *   bpf_iter_num_new(&it, 0, 10);
  *   while ((p = bpf_iter_num_next(&t))) {
  *       x = p;
  *       while (x--) {} // <<-- infinite loop here
  *   }
  *
  */
 static bool iter_active_depths_differ(struct bpf_verifier_state *old, struct bpf_verifier_state *cur)
 {
         struct bpf_reg_state *slot, *cur_slot;
         struct bpf_func_state *state;
         int i, fr;
 
         for (fr = old->curframe; fr >= 0; fr--) {
                 state = old->frame[fr];
                 for (i = 0; i < state->allocated_stack / BPF_REG_SIZE; i++) {
                         if (state->stack[i].slot_type[0] != STACK_ITER)
                                 continue;
 
                         slot = &state->stack[i].spilled_ptr;
                         if (slot->iter.state != BPF_ITER_STATE_ACTIVE)
                                 continue;
 
                         cur_slot = &cur->frame[fr]->stack[i].spilled_ptr;
                         if (cur_slot->iter.depth != slot->iter.depth)
                                 return true;
                 }
         }
         return false;
 }
 
 static int is_state_visited(struct bpf_verifier_env *env, int insn_idx)
 {
         struct bpf_verifier_state_list *new_sl;
         struct bpf_verifier_state_list *sl, **pprev;
         struct bpf_verifier_state *cur = env->cur_state, *new, *loop_entry;
         int i, j, n, err, states_cnt = 0;
         bool force_new_state = env->test_state_freq || is_force_checkpoint(env, insn_idx);
         bool add_new_state = force_new_state;
         bool force_exact;
 
         /* bpf progs typically have pruning point every 4 instructions
          * http://vger.kernel.org/bpfconf2019.html#session-1
          * Do not add new state for future pruning if the verifier hasn't seen
          * at least 2 jumps and at least 8 instructions.
          * This heuristics helps decrease 'total_states' and 'peak_states' metric.
          * In tests that amounts to up to 50% reduction into total verifier
          * memory consumption and 20% verifier time speedup.
          */
         if (env->jmps_processed - env->prev_jmps_processed >= 2 &&
             env->insn_processed - env->prev_insn_processed >= 8)
                 add_new_state = true;
 
         pprev = explored_state(env, insn_idx);
         sl = *pprev;
 
         clean_live_states(env, insn_idx, cur);
 
         while (sl) {
                 states_cnt++;
                 if (sl->state.insn_idx != insn_idx)
                         goto next;
 
                 if (sl->state.branches) {
                         struct bpf_func_state *frame = sl->state.frame[sl->state.curframe];
 
                         if (frame->in_async_callback_fn &&
                             frame->async_entry_cnt != cur->frame[cur->curframe]->async_entry_cnt) {
                                 /* Different async_entry_cnt means that the verifier is
                                  * processing another entry into async callback.
                                  * Seeing the same state is not an indication of infinite
                                  * loop or infinite recursion.
                                  * But finding the same state doesn't mean that it's safe
                                  * to stop processing the current state. The previous state
                                  * hasn't yet reached bpf_exit, since state.branches > 0.
                                  * Checking in_async_callback_fn alone is not enough either.
                                  * Since the verifier still needs to catch infinite loops
                                  * inside async callbacks.
                                  */
                                 goto skip_inf_loop_check;
                         }
                         /* BPF open-coded iterators loop detection is special.
                          * states_maybe_looping() logic is too simplistic in detecting
                          * states that *might* be equivalent, because it doesn't know
                          * about ID remapping, so don't even perform it.
                          * See process_iter_next_call() and iter_active_depths_differ()
                          * for overview of the logic. When current and one of parent
                          * states are detected as equivalent, it's a good thing: we prove
                          * convergence and can stop simulating further iterations.
                          * It's safe to assume that iterator loop will finish, taking into
                          * account iter_next() contract of eventually returning
                          * sticky NULL result.
                          *
                          * Note, that states have to be compared exactly in this case because
                          * read and precision marks might not be finalized inside the loop.
                          * E.g. as in the program below:
                          *
                          *     1. r7 = -16
                          *     2. r6 = bpf_get_prandom_u32()
                          *     3. while (bpf_iter_num_next(&fp[-8])) {
                          *     4.   if (r6 != 42) {
                          *     5.     r7 = -32
                          *     6.     r6 = bpf_get_prandom_u32()
                          *     7.     continue
                          *     8.   }
                          *     9.   r0 = r10
                          *    10.   r0 += r7
                          *    11.   r8 = *(u64 *)(r0 + 0)
                          *    12.   r6 = bpf_get_prandom_u32()
                          *    13. }
                          *
                          * Here verifier would first visit path 1-3, create a checkpoint at 3
                          * with r7=-16, continue to 4-7,3. Existing checkpoint at 3 does
                          * not have read or precision mark for r7 yet, thus inexact states
                          * comparison would discard current state with r7=-32
                          * => unsafe memory access at 11 would not be caught.
                          */
                         if (is_iter_next_insn(env, insn_idx)) {
                                 if (states_equal(env, &sl->state, cur, RANGE_WITHIN)) {
                                         struct bpf_func_state *cur_frame;
                                         struct bpf_reg_state *iter_state, *iter_reg;
                                         int spi;
 
                                         cur_frame = cur->frame[cur->curframe];
                                         /* btf_check_iter_kfuncs() enforces that
                                          * iter state pointer is always the first arg
                                          */
                                         iter_reg = &cur_frame->regs[BPF_REG_1];
                                         /* current state is valid due to states_equal(),
                                          * so we can assume valid iter and reg state,
                                          * no need for extra (re-)validations
                                          */
                                         spi = __get_spi(iter_reg->off + iter_reg->var_off.value);
                                         iter_state = &func(env, iter_reg)->stack[spi].spilled_ptr;
                                         if (iter_state->iter.state == BPF_ITER_STATE_ACTIVE) {
                                                 update_loop_entry(cur, &sl->state);
                                                 goto hit;
                                         }
                                 }
                                 goto skip_inf_loop_check;
                         }
                         if (is_may_goto_insn_at(env, insn_idx)) {
                                 if (sl->state.may_goto_depth != cur->may_goto_depth &&
                                     states_equal(env, &sl->state, cur, RANGE_WITHIN)) {
                                         update_loop_entry(cur, &sl->state);
                                         goto hit;
                                 }
                         }
                         if (calls_callback(env, insn_idx)) {
                                 if (states_equal(env, &sl->state, cur, RANGE_WITHIN))
                                         goto hit;
                                 goto skip_inf_loop_check;
                         }
                         /* attempt to detect infinite loop to avoid unnecessary doomed work */
                         if (states_maybe_looping(&sl->state, cur) &&
                             states_equal(env, &sl->state, cur, EXACT) &&
                             !iter_active_depths_differ(&sl->state, cur) &&
                             sl->state.may_goto_depth == cur->may_goto_depth &&
                             sl->state.callback_unroll_depth == cur->callback_unroll_depth) {
                                 verbose_linfo(env, insn_idx, "; ");
                                 verbose(env, "infinite loop detected at insn %d\n", insn_idx);
                                 verbose(env, "cur state:");
                                 print_verifier_state(env, cur->frame[cur->curframe], true);
                                 verbose(env, "old state:");
                                 print_verifier_state(env, sl->state.frame[cur->curframe], true);
                                 return -EINVAL;
                         }
                         /* if the verifier is processing a loop, avoid adding new state
                          * too often, since different loop iterations have distinct
                          * states and may not help future pruning.
                          * This threshold shouldn't be too low to make sure that
                          * a loop with large bound will be rejected quickly.
                          * The most abusive loop will be:
                          * r1 += 1
                          * if r1 < 1000000 goto pc-2
                          * 1M insn_procssed limit / 100 == 10k peak states.
                          * This threshold shouldn't be too high either, since states
                          * at the end of the loop are likely to be useful in pruning.
                          */
 skip_inf_loop_check:
                         if (!force_new_state &&
                             env->jmps_processed - env->prev_jmps_processed < 20 &&
                             env->insn_processed - env->prev_insn_processed < 100)
                                 add_new_state = false;
                         goto miss;
                 }
                 /* If sl->state is a part of a loop and this loop's entry is a part of
                  * current verification path then states have to be compared exactly.
                  * 'force_exact' is needed to catch the following case:
                  *
                  *                initial     Here state 'succ' was processed first,
                  *                  |         it was eventually tracked to produce a
                  *                  V         state identical to 'hdr'.
                  *     .---------> hdr        All branches from 'succ' had been explored
                  *     |            |         and thus 'succ' has its .branches == 0.
                  *     |            V
                  *     |    .------...        Suppose states 'cur' and 'succ' correspond
                  *     |    |       |         to the same instruction + callsites.
                  *     |    V       V         In such case it is necessary to check
                  *     |   ...     ...        if 'succ' and 'cur' are states_equal().
                  *     |    |       |         If 'succ' and 'cur' are a part of the
                  *     |    V       V         same loop exact flag has to be set.
                  *     |   succ <- cur        To check if that is the case, verify
                  *     |    |                 if loop entry of 'succ' is in current
                  *     |    V                 DFS path.
                  *     |   ...
                  *     |    |
                  *     '----'
                  *
                  * Additional details are in the comment before get_loop_entry().
                  */
                 loop_entry = get_loop_entry(&sl->state);
                 force_exact = loop_entry && loop_entry->branches > 0;
                 if (states_equal(env, &sl->state, cur, force_exact ? RANGE_WITHIN : NOT_EXACT)) {
                         if (force_exact)
                                 update_loop_entry(cur, loop_entry);
 hit:
                         sl->hit_cnt++;
                         /* reached equivalent register/stack state,
                          * prune the search.
                          * Registers read by the continuation are read by us.
                          * If we have any write marks in env->cur_state, they
                          * will prevent corresponding reads in the continuation
                          * from reaching our parent (an explored_state).  Our
                          * own state will get the read marks recorded, but
                          * they'll be immediately forgotten as we're pruning
                          * this state and will pop a new one.
                          */
                         err = propagate_liveness(env, &sl->state, cur);
 
                         /* if previous state reached the exit with precision and
                          * current state is equivalent to it (except precision marks)
                          * the precision needs to be propagated back in
                          * the current state.
                          */
                         if (is_jmp_point(env, env->insn_idx))
                                 err = err ? : push_jmp_history(env, cur, 0);
                         err = err ? : propagate_precision(env, &sl->state);
                         if (err)
                                 return err;
                         return 1;
                 }
 miss:
                 /* when new state is not going to be added do not increase miss count.
                  * Otherwise several loop iterations will remove the state
                  * recorded earlier. The goal of these heuristics is to have
                  * states from some iterations of the loop (some in the beginning
                  * and some at the end) to help pruning.
                  */
                 if (add_new_state)
                         sl->miss_cnt++;
                 /* heuristic to determine whether this state is beneficial
                  * to keep checking from state equivalence point of view.
                  * Higher numbers increase max_states_per_insn and verification time,
                  * but do not meaningfully decrease insn_processed.
                  * 'n' controls how many times state could miss before eviction.
                  * Use bigger 'n' for checkpoints because evicting checkpoint states
                  * too early would hinder iterator convergence.
                  */
                 n = is_force_checkpoint(env, insn_idx) && sl->state.branches > 0 ? 64 : 3;
                 if (sl->miss_cnt > sl->hit_cnt * n + n) {
                         /* the state is unlikely to be useful. Remove it to
                          * speed up verification
                          */
                         *pprev = sl->next;
                         if (sl->state.frame[0]->regs[0].live & REG_LIVE_DONE &&
                             !sl->state.used_as_loop_entry) {
                                 u32 br = sl->state.branches;
 
                                 WARN_ONCE(br,
                                           "BUG live_done but branches_to_explore %d\n",
                                           br);
                                 free_verifier_state(&sl->state, false);
                                 kfree(sl);
                                 env->peak_states--;
                         } else {
                                 /* cannot free this state, since parentage chain may
                                  * walk it later. Add it for free_list instead to
                                  * be freed at the end of verification
                                  */
                                 sl->next = env->free_list;
                                 env->free_list = sl;
                         }
                         sl = *pprev;
                         continue;
                 }
 next:
                 pprev = &sl->next;
                 sl = *pprev;
         }
 
         if (env->max_states_per_insn < states_cnt)
                 env->max_states_per_insn = states_cnt;
 
         if (!env->bpf_capable && states_cnt > BPF_COMPLEXITY_LIMIT_STATES)
                 return 0;
 
         if (!add_new_state)
                 return 0;
 
         /* There were no equivalent states, remember the current one.
          * Technically the current state is not proven to be safe yet,
          * but it will either reach outer most bpf_exit (which means it's safe)
          * or it will be rejected. When there are no loops the verifier won't be
          * seeing this tuple (frame[0].callsite, frame[1].callsite, .. insn_idx)
          * again on the way to bpf_exit.
          * When looping the sl->state.branches will be > 0 and this state
          * will not be considered for equivalence until branches == 0.
          */
         new_sl = kzalloc(sizeof(struct bpf_verifier_state_list), GFP_KERNEL);
         if (!new_sl)
                 return -ENOMEM;
         env->total_states++;
         env->peak_states++;
         env->prev_jmps_processed = env->jmps_processed;
         env->prev_insn_processed = env->insn_processed;
 
         /* forget precise markings we inherited, see __mark_chain_precision */
         if (env->bpf_capable)
                 mark_all_scalars_imprecise(env, cur);
 
         /* add new state to the head of linked list */
         new = &new_sl->state;
         err = copy_verifier_state(new, cur);
         if (err) {
                 free_verifier_state(new, false);
                 kfree(new_sl);
                 return err;
         }
         new->insn_idx = insn_idx;
         WARN_ONCE(new->branches != 1,
                   "BUG is_state_visited:branches_to_explore=%d insn %d\n", new->branches, insn_idx);
 
         cur->parent = new;
         cur->first_insn_idx = insn_idx;
         cur->dfs_depth = new->dfs_depth + 1;
         clear_jmp_history(cur);
         new_sl->next = *explored_state(env, insn_idx);
         *explored_state(env, insn_idx) = new_sl;
         /* connect new state to parentage chain. Current frame needs all
          * registers connected. Only r6 - r9 of the callers are alive (pushed
          * to the stack implicitly by JITs) so in callers' frames connect just
          * r6 - r9 as an optimization. Callers will have r1 - r5 connected to
          * the state of the call instruction (with WRITTEN set), and r0 comes
          * from callee with its full parentage chain, anyway.
          */
         /* clear write marks in current state: the writes we did are not writes
          * our child did, so they don't screen off its reads from us.
          * (There are no read marks in current state, because reads always mark
          * their parent and current state never has children yet.  Only
          * explored_states can get read marks.)
          */
         for (j = 0; j <= cur->curframe; j++) {
                 for (i = j < cur->curframe ? BPF_REG_6 : 0; i < BPF_REG_FP; i++)
                         cur->frame[j]->regs[i].parent = &new->frame[j]->regs[i];
                 for (i = 0; i < BPF_REG_FP; i++)
                         cur->frame[j]->regs[i].live = REG_LIVE_NONE;
         }
 
         /* all stack frames are accessible from callee, clear them all */
         for (j = 0; j <= cur->curframe; j++) {
                 struct bpf_func_state *frame = cur->frame[j];
                 struct bpf_func_state *newframe = new->frame[j];
 
                 for (i = 0; i < frame->allocated_stack / BPF_REG_SIZE; i++) {
                         frame->stack[i].spilled_ptr.live = REG_LIVE_NONE;
                         frame->stack[i].spilled_ptr.parent =
                                                 &newframe->stack[i].spilled_ptr;
                 }
         }
         return 0;
 }
 
 /* Return true if it's OK to have the same insn return a different type. */
 static bool reg_type_mismatch_ok(enum bpf_reg_type type)
 {
         switch (base_type(type)) {
         case PTR_TO_CTX:
         case PTR_TO_SOCKET:
         case PTR_TO_SOCK_COMMON:
         case PTR_TO_TCP_SOCK:
         case PTR_TO_XDP_SOCK:
         case PTR_TO_BTF_ID:
         case PTR_TO_ARENA:
                 return false;
         default:
                 return true;
         }
 }
 
 /* If an instruction was previously used with particular pointer types, then we
  * need to be careful to avoid cases such as the below, where it may be ok
  * for one branch accessing the pointer, but not ok for the other branch:
  *
  * R1 = sock_ptr
  * goto X;
  * ...
  * R1 = some_other_valid_ptr;
  * goto X;
  * ...
  * R2 = *(u32 *)(R1 + 0);
  */
 static bool reg_type_mismatch(enum bpf_reg_type src, enum bpf_reg_type prev)
 {
         return src != prev && (!reg_type_mismatch_ok(src) ||
                                !reg_type_mismatch_ok(prev));
 }
 
 static int save_aux_ptr_type(struct bpf_verifier_env *env, enum bpf_reg_type type,
                              bool allow_trust_mismatch)
 {
         enum bpf_reg_type *prev_type = &env->insn_aux_data[env->insn_idx].ptr_type;
 
         if (*prev_type == NOT_INIT) {
                 /* Saw a valid insn
                  * dst_reg = *(u32 *)(src_reg + off)
                  * save type to validate intersecting paths
                  */
                 *prev_type = type;
         } else if (reg_type_mismatch(type, *prev_type)) {
                 /* Abuser program is trying to use the same insn
                  * dst_reg = *(u32*) (src_reg + off)
                  * with different pointer types:
                  * src_reg == ctx in one branch and
                  * src_reg == stack|map in some other branch.
                  * Reject it.
                  */
                 if (allow_trust_mismatch &&
                     base_type(type) == PTR_TO_BTF_ID &&
                     base_type(*prev_type) == PTR_TO_BTF_ID) {
                         /*
                          * Have to support a use case when one path through
                          * the program yields TRUSTED pointer while another
                          * is UNTRUSTED. Fallback to UNTRUSTED to generate
                          * BPF_PROBE_MEM/BPF_PROBE_MEMSX.
                          */
                         *prev_type = PTR_TO_BTF_ID | PTR_UNTRUSTED;
                 } else {
                         verbose(env, "same insn cannot be used with different pointers\n");
                         return -EINVAL;
                 }
         }
 
         return 0;
 }
 
 static int do_check(struct bpf_verifier_env *env)
 {
         bool pop_log = !(env->log.level & BPF_LOG_LEVEL2);
         struct bpf_verifier_state *state = env->cur_state;
         struct bpf_insn *insns = env->prog->insnsi;
         struct bpf_reg_state *regs;
         int insn_cnt = env->prog->len;
         bool do_print_state = false;
         int prev_insn_idx = -1;
 
         for (;;) {
                 bool exception_exit = false;
                 struct bpf_insn *insn;
                 u8 class;
                 int err;
 
                 /* reset current history entry on each new instruction */
                 env->cur_hist_ent = NULL;
 
                 env->prev_insn_idx = prev_insn_idx;
                 if (env->insn_idx >= insn_cnt) {
                         verbose(env, "invalid insn idx %d insn_cnt %d\n",
                                 env->insn_idx, insn_cnt);
                         return -EFAULT;
                 }
 
                 insn = &insns[env->insn_idx];
                 class = BPF_CLASS(insn->code);
 
                 if (++env->insn_processed > BPF_COMPLEXITY_LIMIT_INSNS) {
                         verbose(env,
                                 "BPF program is too large. Processed %d insn\n",
                                 env->insn_processed);
                         return -E2BIG;
                 }
 
                 state->last_insn_idx = env->prev_insn_idx;
 
                 if (is_prune_point(env, env->insn_idx)) {
                         err = is_state_visited(env, env->insn_idx);
                         if (err < 0)
                                 return err;
                         if (err == 1) {
                                 /* found equivalent state, can prune the search */
                                 if (env->log.level & BPF_LOG_LEVEL) {
                                         if (do_print_state)
                                                 verbose(env, "\nfrom %d to %d%s: safe\n",
                                                         env->prev_insn_idx, env->insn_idx,
                                                         env->cur_state->speculative ?
                                                         " (speculative execution)" : "");
                                         else
                                                 verbose(env, "%d: safe\n", env->insn_idx);
                                 }
                                 goto process_bpf_exit;
                         }
                 }
 
                 if (is_jmp_point(env, env->insn_idx)) {
                         err = push_jmp_history(env, state, 0);
                         if (err)
                                 return err;
                 }
 
                 if (signal_pending(current))
                         return -EAGAIN;
 
                 if (need_resched())
                         cond_resched();
 
                 if (env->log.level & BPF_LOG_LEVEL2 && do_print_state) {
                         verbose(env, "\nfrom %d to %d%s:",
                                 env->prev_insn_idx, env->insn_idx,
                                 env->cur_state->speculative ?
                                 " (speculative execution)" : "");
                         print_verifier_state(env, state->frame[state->curframe], true);
                         do_print_state = false;
                 }
 
                 if (env->log.level & BPF_LOG_LEVEL) {
                         const struct bpf_insn_cbs cbs = {
                                 .cb_call        = disasm_kfunc_name,
                                 .cb_print       = verbose,
                                 .private_data   = env,
                         };
 
                         if (verifier_state_scratched(env))
                                 print_insn_state(env, state->frame[state->curframe]);
 
                         verbose_linfo(env, env->insn_idx, "; ");
                         env->prev_log_pos = env->log.end_pos;
                         verbose(env, "%d: ", env->insn_idx);
                         print_bpf_insn(&cbs, insn, env->allow_ptr_leaks);
                         env->prev_insn_print_pos = env->log.end_pos - env->prev_log_pos;
                         env->prev_log_pos = env->log.end_pos;
                 }
 
                 if (bpf_prog_is_offloaded(env->prog->aux)) {
                         err = bpf_prog_offload_verify_insn(env, env->insn_idx,
                                                            env->prev_insn_idx);
                         if (err)
                                 return err;
                 }
 
                 regs = cur_regs(env);
                 sanitize_mark_insn_seen(env);
                 prev_insn_idx = env->insn_idx;
 
                 if (class == BPF_ALU || class == BPF_ALU64) {
                         err = check_alu_op(env, insn);
                         if (err)
                                 return err;
 
                 } else if (class == BPF_LDX) {
                         enum bpf_reg_type src_reg_type;
 
                         /* check for reserved fields is already done */
 
                         /* check src operand */
                         err = check_reg_arg(env, insn->src_reg, SRC_OP);
                         if (err)
                                 return err;
 
                         err = check_reg_arg(env, insn->dst_reg, DST_OP_NO_MARK);
                         if (err)
                                 return err;
 
                         src_reg_type = regs[insn->src_reg].type;
 
                         /* check that memory (src_reg + off) is readable,
                          * the state of dst_reg will be updated by this func
                          */
                         err = check_mem_access(env, env->insn_idx, insn->src_reg,
                                                insn->off, BPF_SIZE(insn->code),
                                                BPF_READ, insn->dst_reg, false,
                                                BPF_MODE(insn->code) == BPF_MEMSX);
                         err = err ?: save_aux_ptr_type(env, src_reg_type, true);
                         err = err ?: reg_bounds_sanity_check(env, &regs[insn->dst_reg], "ldx");
                         if (err)
                                 return err;
                 } else if (class == BPF_STX) {
                         enum bpf_reg_type dst_reg_type;
 
                         if (BPF_MODE(insn->code) == BPF_ATOMIC) {
                                 err = check_atomic(env, env->insn_idx, insn);
                                 if (err)
                                         return err;
                                 env->insn_idx++;
                                 continue;
                         }
 
                         if (BPF_MODE(insn->code) != BPF_MEM || insn->imm != 0) {
                                 verbose(env, "BPF_STX uses reserved fields\n");
                                 return -EINVAL;
                         }
 
                         /* check src1 operand */
                         err = check_reg_arg(env, insn->src_reg, SRC_OP);
                         if (err)
                                 return err;
                         /* check src2 operand */
                         err = check_reg_arg(env, insn->dst_reg, SRC_OP);
                         if (err)
                                 return err;
 
                         dst_reg_type = regs[insn->dst_reg].type;
 
                         /* check that memory (dst_reg + off) is writeable */
                         err = check_mem_access(env, env->insn_idx, insn->dst_reg,
                                                insn->off, BPF_SIZE(insn->code),
                                                BPF_WRITE, insn->src_reg, false, false);
                         if (err)
                                 return err;
 
                         err = save_aux_ptr_type(env, dst_reg_type, false);
                         if (err)
                                 return err;
                 } else if (class == BPF_ST) {
                         enum bpf_reg_type dst_reg_type;
 
                         if (BPF_MODE(insn->code) != BPF_MEM ||
                             insn->src_reg != BPF_REG_0) {
                                 verbose(env, "BPF_ST uses reserved fields\n");
                                 return -EINVAL;
                         }
                         /* check src operand */
                         err = check_reg_arg(env, insn->dst_reg, SRC_OP);
                         if (err)
                                 return err;
 
                         dst_reg_type = regs[insn->dst_reg].type;
 
                         /* check that memory (dst_reg + off) is writeable */
                         err = check_mem_access(env, env->insn_idx, insn->dst_reg,
                                                insn->off, BPF_SIZE(insn->code),
                                                BPF_WRITE, -1, false, false);
                         if (err)
                                 return err;
 
                         err = save_aux_ptr_type(env, dst_reg_type, false);
                         if (err)
                                 return err;
                 } else if (class == BPF_JMP || class == BPF_JMP32) {
                         u8 opcode = BPF_OP(insn->code);
 
                         env->jmps_processed++;
                         if (opcode == BPF_CALL) {
                                 if (BPF_SRC(insn->code) != BPF_K ||
                                     (insn->src_reg != BPF_PSEUDO_KFUNC_CALL
                                      && insn->off != 0) ||
                                     (insn->src_reg != BPF_REG_0 &&
                                      insn->src_reg != BPF_PSEUDO_CALL &&
                                      insn->src_reg != BPF_PSEUDO_KFUNC_CALL) ||
                                     insn->dst_reg != BPF_REG_0 ||
                                     class == BPF_JMP32) {
                                         verbose(env, "BPF_CALL uses reserved fields\n");
                                         return -EINVAL;
                                 }
 
                                 if (env->cur_state->active_lock.ptr) {
                                         if ((insn->src_reg == BPF_REG_0 && insn->imm != BPF_FUNC_spin_unlock) ||
                                             (insn->src_reg == BPF_PSEUDO_KFUNC_CALL &&
                                              (insn->off != 0 || !is_bpf_graph_api_kfunc(insn->imm)))) {
                                                 verbose(env, "function calls are not allowed while holding a lock\n");
                                                 return -EINVAL;
                                         }
                                 }
                                 if (insn->src_reg == BPF_PSEUDO_CALL) {
                                         err = check_func_call(env, insn, &env->insn_idx);
                                 } else if (insn->src_reg == BPF_PSEUDO_KFUNC_CALL) {
                                         err = check_kfunc_call(env, insn, &env->insn_idx);
                                         if (!err && is_bpf_throw_kfunc(insn)) {
                                                 exception_exit = true;
                                                 goto process_bpf_exit_full;
                                         }
                                 } else {
                                         err = check_helper_call(env, insn, &env->insn_idx);
                                 }
                                 if (err)
                                         return err;
 
                                 mark_reg_scratched(env, BPF_REG_0);
                         } else if (opcode == BPF_JA) {
                                 if (BPF_SRC(insn->code) != BPF_K ||
                                     insn->src_reg != BPF_REG_0 ||
                                     insn->dst_reg != BPF_REG_0 ||
                                     (class == BPF_JMP && insn->imm != 0) ||
                                     (class == BPF_JMP32 && insn->off != 0)) {
                                         verbose(env, "BPF_JA uses reserved fields\n");
                                         return -EINVAL;
                                 }
 
                                 if (class == BPF_JMP)
                                         env->insn_idx += insn->off + 1;
                                 else
                                         env->insn_idx += insn->imm + 1;
                                 continue;
 
                         } else if (opcode == BPF_EXIT) {
                                 if (BPF_SRC(insn->code) != BPF_K ||
                                     insn->imm != 0 ||
                                     insn->src_reg != BPF_REG_0 ||
                                     insn->dst_reg != BPF_REG_0 ||
                                     class == BPF_JMP32) {
                                         verbose(env, "BPF_EXIT uses reserved fields\n");
                                         return -EINVAL;
                                 }
 process_bpf_exit_full:
                                 if (env->cur_state->active_lock.ptr && !env->cur_state->curframe) {
                                         verbose(env, "bpf_spin_unlock is missing\n");
                                         return -EINVAL;
                                 }
 
                                 if (env->cur_state->active_rcu_lock && !env->cur_state->curframe) {
                                         verbose(env, "bpf_rcu_read_unlock is missing\n");
                                         return -EINVAL;
                                 }
 
                                 if (env->cur_state->active_preempt_lock && !env->cur_state->curframe) {
                                         verbose(env, "%d bpf_preempt_enable%s missing\n",
                                                 env->cur_state->active_preempt_lock,
                                                 env->cur_state->active_preempt_lock == 1 ? " is" : "(s) are");
                                         return -EINVAL;
                                 }
 
                                 /* We must do check_reference_leak here before
                                  * prepare_func_exit to handle the case when
                                  * state->curframe > 0, it may be a callback
                                  * function, for which reference_state must
                                  * match caller reference state when it exits.
                                  */
                                 err = check_reference_leak(env, exception_exit);
                                 if (err)
                                         return err;
 
                                 /* The side effect of the prepare_func_exit
                                  * which is being skipped is that it frees
                                  * bpf_func_state. Typically, process_bpf_exit
                                  * will only be hit with outermost exit.
                                  * copy_verifier_state in pop_stack will handle
                                  * freeing of any extra bpf_func_state left over
                                  * from not processing all nested function
                                  * exits. We also skip return code checks as
                                  * they are not needed for exceptional exits.
                                  */
                                 if (exception_exit)
                                         goto process_bpf_exit;
 
                                 if (state->curframe) {
                                         /* exit from nested function */
                                         err = prepare_func_exit(env, &env->insn_idx);
                                         if (err)
                                                 return err;
                                         do_print_state = true;
                                         continue;
                                 }
 
                                 err = check_return_code(env, BPF_REG_0, "R0");
                                 if (err)
                                         return err;
 process_bpf_exit:
                                 mark_verifier_state_scratched(env);
                                 update_branch_counts(env, env->cur_state);
                                 err = pop_stack(env, &prev_insn_idx,
                                                 &env->insn_idx, pop_log);
                                 if (err < 0) {
                                         if (err != -ENOENT)
                                                 return err;
                                         break;
                                 } else {
                                         do_print_state = true;
                                         continue;
                                 }
                         } else {
                                 err = check_cond_jmp_op(env, insn, &env->insn_idx);
                                 if (err)
                                         return err;
                         }
                 } else if (class == BPF_LD) {
                         u8 mode = BPF_MODE(insn->code);
 
                         if (mode == BPF_ABS || mode == BPF_IND) {
                                 err = check_ld_abs(env, insn);
                                 if (err)
                                         return err;
 
                         } else if (mode == BPF_IMM) {
                                 err = check_ld_imm(env, insn);
                                 if (err)
                                         return err;
 
                                 env->insn_idx++;
                                 sanitize_mark_insn_seen(env);
                         } else {
                                 verbose(env, "invalid BPF_LD mode\n");
                                 return -EINVAL;
                         }
                 } else {
                         verbose(env, "unknown insn class %d\n", class);
                         return -EINVAL;
                 }
 
                 env->insn_idx++;
         }
 
         return 0;
 }
 
 static int find_btf_percpu_datasec(struct btf *btf)
 {
         const struct btf_type *t;
         const char *tname;
         int i, n;
 
         /*
          * Both vmlinux and module each have their own ".data..percpu"
          * DATASECs in BTF. So for module's case, we need to skip vmlinux BTF
          * types to look at only module's own BTF types.
          */
         n = btf_nr_types(btf);
         if (btf_is_module(btf))
                 i = btf_nr_types(btf_vmlinux);
         else
                 i = 1;
 
         for(; i < n; i++) {
                 t = btf_type_by_id(btf, i);
                 if (BTF_INFO_KIND(t->info) != BTF_KIND_DATASEC)
                         continue;
 
                 tname = btf_name_by_offset(btf, t->name_off);
                 if (!strcmp(tname, ".data..percpu"))
                         return i;
         }
 
         return -ENOENT;
 }
 
 /* replace pseudo btf_id with kernel symbol address */
 static int check_pseudo_btf_id(struct bpf_verifier_env *env,
                                struct bpf_insn *insn,
                                struct bpf_insn_aux_data *aux)
 {
         const struct btf_var_secinfo *vsi;
         const struct btf_type *datasec;
         struct btf_mod_pair *btf_mod;
         const struct btf_type *t;
         const char *sym_name;
         bool percpu = false;
         u32 type, id = insn->imm;
         struct btf *btf;
         s32 datasec_id;
         u64 addr;
         int i, btf_fd, err;
 
         btf_fd = insn[1].imm;
         if (btf_fd) {
                 btf = btf_get_by_fd(btf_fd);
                 if (IS_ERR(btf)) {
                         verbose(env, "invalid module BTF object FD specified.\n");
                         return -EINVAL;
                 }
         } else {
                 if (!btf_vmlinux) {
                         verbose(env, "kernel is missing BTF, make sure CONFIG_DEBUG_INFO_BTF=y is specified in Kconfig.\n");
                         return -EINVAL;
                 }
                 btf = btf_vmlinux;
                 btf_get(btf);
         }
 
         t = btf_type_by_id(btf, id);
         if (!t) {
                 verbose(env, "ldimm64 insn specifies invalid btf_id %d.\n", id);
                 err = -ENOENT;
                 goto err_put;
         }
 
         if (!btf_type_is_var(t) && !btf_type_is_func(t)) {
                 verbose(env, "pseudo btf_id %d in ldimm64 isn't KIND_VAR or KIND_FUNC\n", id);
                 err = -EINVAL;
                 goto err_put;
         }
 
         sym_name = btf_name_by_offset(btf, t->name_off);
         addr = kallsyms_lookup_name(sym_name);
         if (!addr) {
                 verbose(env, "ldimm64 failed to find the address for kernel symbol '%s'.\n",
                         sym_name);
                 err = -ENOENT;
                 goto err_put;
         }
         insn[0].imm = (u32)addr;
         insn[1].imm = addr >> 32;
 
         if (btf_type_is_func(t)) {
                 aux->btf_var.reg_type = PTR_TO_MEM | MEM_RDONLY;
                 aux->btf_var.mem_size = 0;
                 goto check_btf;
         }
 
         datasec_id = find_btf_percpu_datasec(btf);
         if (datasec_id > 0) {
                 datasec = btf_type_by_id(btf, datasec_id);
                 for_each_vsi(i, datasec, vsi) {
                         if (vsi->type == id) {
                                 percpu = true;
                                 break;
                         }
                 }
         }
 
         type = t->type;
         t = btf_type_skip_modifiers(btf, type, NULL);
         if (percpu) {
                 aux->btf_var.reg_type = PTR_TO_BTF_ID | MEM_PERCPU;
                 aux->btf_var.btf = btf;
                 aux->btf_var.btf_id = type;
         } else if (!btf_type_is_struct(t)) {
                 const struct btf_type *ret;
                 const char *tname;
                 u32 tsize;
 
                 /* resolve the type size of ksym. */
                 ret = btf_resolve_size(btf, t, &tsize);
                 if (IS_ERR(ret)) {
                         tname = btf_name_by_offset(btf, t->name_off);
                         verbose(env, "ldimm64 unable to resolve the size of type '%s': %ld\n",
                                 tname, PTR_ERR(ret));
                         err = -EINVAL;
                         goto err_put;
                 }
                 aux->btf_var.reg_type = PTR_TO_MEM | MEM_RDONLY;
                 aux->btf_var.mem_size = tsize;
         } else {
                 aux->btf_var.reg_type = PTR_TO_BTF_ID;
                 aux->btf_var.btf = btf;
                 aux->btf_var.btf_id = type;
         }
 check_btf:
         /* check whether we recorded this BTF (and maybe module) already */
         for (i = 0; i < env->used_btf_cnt; i++) {
                 if (env->used_btfs[i].btf == btf) {
                         btf_put(btf);
                         return 0;
                 }
         }
 
         if (env->used_btf_cnt >= MAX_USED_BTFS) {
                 err = -E2BIG;
                 goto err_put;
         }
 
         btf_mod = &env->used_btfs[env->used_btf_cnt];
         btf_mod->btf = btf;
         btf_mod->module = NULL;
 
         /* if we reference variables from kernel module, bump its refcount */
         if (btf_is_module(btf)) {
                 btf_mod->module = btf_try_get_module(btf);
                 if (!btf_mod->module) {
                         err = -ENXIO;
                         goto err_put;
                 }
         }
 
         env->used_btf_cnt++;
 
         return 0;
 err_put:
         btf_put(btf);
         return err;
 }
 
 static bool is_tracing_prog_type(enum bpf_prog_type type)
 {
         switch (type) {
         case BPF_PROG_TYPE_KPROBE:
         case BPF_PROG_TYPE_TRACEPOINT:
         case BPF_PROG_TYPE_PERF_EVENT:
         case BPF_PROG_TYPE_RAW_TRACEPOINT:
         case BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE:
                 return true;
         default:
                 return false;
         }
 }
 
 static int check_map_prog_compatibility(struct bpf_verifier_env *env,
                                         struct bpf_map *map,
                                         struct bpf_prog *prog)
 
 {
         enum bpf_prog_type prog_type = resolve_prog_type(prog);
 
         if (btf_record_has_field(map->record, BPF_LIST_HEAD) ||
             btf_record_has_field(map->record, BPF_RB_ROOT)) {
                 if (is_tracing_prog_type(prog_type)) {
                         verbose(env, "tracing progs cannot use bpf_{list_head,rb_root} yet\n");
                         return -EINVAL;
                 }
         }
 
         if (btf_record_has_field(map->record, BPF_SPIN_LOCK)) {
                 if (prog_type == BPF_PROG_TYPE_SOCKET_FILTER) {
                         verbose(env, "socket filter progs cannot use bpf_spin_lock yet\n");
                         return -EINVAL;
                 }
 
                 if (is_tracing_prog_type(prog_type)) {
                         verbose(env, "tracing progs cannot use bpf_spin_lock yet\n");
                         return -EINVAL;
                 }
         }
 
         if (btf_record_has_field(map->record, BPF_TIMER)) {
                 if (is_tracing_prog_type(prog_type)) {
                         verbose(env, "tracing progs cannot use bpf_timer yet\n");
                         return -EINVAL;
                 }
         }
 
         if (btf_record_has_field(map->record, BPF_WORKQUEUE)) {
                 if (is_tracing_prog_type(prog_type)) {
                         verbose(env, "tracing progs cannot use bpf_wq yet\n");
                         return -EINVAL;
                 }
         }
 
         if ((bpf_prog_is_offloaded(prog->aux) || bpf_map_is_offloaded(map)) &&
             !bpf_offload_prog_map_match(prog, map)) {
                 verbose(env, "offload device mismatch between prog and map\n");
                 return -EINVAL;
         }
 
         if (map->map_type == BPF_MAP_TYPE_STRUCT_OPS) {
                 verbose(env, "bpf_struct_ops map cannot be used in prog\n");
                 return -EINVAL;
         }
 
         if (prog->sleepable)
                 switch (map->map_type) {
                 case BPF_MAP_TYPE_HASH:
                 case BPF_MAP_TYPE_LRU_HASH:
                 case BPF_MAP_TYPE_ARRAY:
                 case BPF_MAP_TYPE_PERCPU_HASH:
                 case BPF_MAP_TYPE_PERCPU_ARRAY:
                 case BPF_MAP_TYPE_LRU_PERCPU_HASH:
                 case BPF_MAP_TYPE_ARRAY_OF_MAPS:
                 case BPF_MAP_TYPE_HASH_OF_MAPS:
                 case BPF_MAP_TYPE_RINGBUF:
                 case BPF_MAP_TYPE_USER_RINGBUF:
                 case BPF_MAP_TYPE_INODE_STORAGE:
                 case BPF_MAP_TYPE_SK_STORAGE:
                 case BPF_MAP_TYPE_TASK_STORAGE:
                 case BPF_MAP_TYPE_CGRP_STORAGE:
                 case BPF_MAP_TYPE_QUEUE:
                 case BPF_MAP_TYPE_STACK:
                 case BPF_MAP_TYPE_ARENA:
                         break;
                 default:
                         verbose(env,
                                 "Sleepable programs can only use array, hash, ringbuf and local storage maps\n");
                         return -EINVAL;
                 }
 
         return 0;
 }
 
 static bool bpf_map_is_cgroup_storage(struct bpf_map *map)
 {
         return (map->map_type == BPF_MAP_TYPE_CGROUP_STORAGE ||
                 map->map_type == BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE);
 }
 
 /* find and rewrite pseudo imm in ld_imm64 instructions:
  *
  * 1. if it accesses map FD, replace it with actual map pointer.
  * 2. if it accesses btf_id of a VAR, replace it with pointer to the var.
  *
  * NOTE: btf_vmlinux is required for converting pseudo btf_id.
  */
 static int resolve_pseudo_ldimm64(struct bpf_verifier_env *env)
 {
         struct bpf_insn *insn = env->prog->insnsi;
         int insn_cnt = env->prog->len;
         int i, j, err;
 
         err = bpf_prog_calc_tag(env->prog);
         if (err)
                 return err;
 
         for (i = 0; i < insn_cnt; i++, insn++) {
                 if (BPF_CLASS(insn->code) == BPF_LDX &&
                     ((BPF_MODE(insn->code) != BPF_MEM && BPF_MODE(insn->code) != BPF_MEMSX) ||
                     insn->imm != 0)) {
                         verbose(env, "BPF_LDX uses reserved fields\n");
                         return -EINVAL;
                 }
 
                 if (insn[0].code == (BPF_LD | BPF_IMM | BPF_DW)) {
                         struct bpf_insn_aux_data *aux;
                         struct bpf_map *map;
                         struct fd f;
                         u64 addr;
                         u32 fd;
 
                         if (i == insn_cnt - 1 || insn[1].code != 0 ||
                             insn[1].dst_reg != 0 || insn[1].src_reg != 0 ||
                             insn[1].off != 0) {
                                 verbose(env, "invalid bpf_ld_imm64 insn\n");
                                 return -EINVAL;
                         }
 
                         if (insn[0].src_reg == 0)
                                 /* valid generic load 64-bit imm */
                                 goto next_insn;
 
                         if (insn[0].src_reg == BPF_PSEUDO_BTF_ID) {
                                 aux = &env->insn_aux_data[i];
                                 err = check_pseudo_btf_id(env, insn, aux);
                                 if (err)
                                         return err;
                                 goto next_insn;
                         }
 
                         if (insn[0].src_reg == BPF_PSEUDO_FUNC) {
                                 aux = &env->insn_aux_data[i];
                                 aux->ptr_type = PTR_TO_FUNC;
                                 goto next_insn;
                         }
 
                         /* In final convert_pseudo_ld_imm64() step, this is
                          * converted into regular 64-bit imm load insn.
                          */
                         switch (insn[0].src_reg) {
                         case BPF_PSEUDO_MAP_VALUE:
                         case BPF_PSEUDO_MAP_IDX_VALUE:
                                 break;
                         case BPF_PSEUDO_MAP_FD:
                         case BPF_PSEUDO_MAP_IDX:
                                 if (insn[1].imm == 0)
                                         break;
                                 fallthrough;
                         default:
                                 verbose(env, "unrecognized bpf_ld_imm64 insn\n");
                                 return -EINVAL;
                         }
 
                         switch (insn[0].src_reg) {
                         case BPF_PSEUDO_MAP_IDX_VALUE:
                         case BPF_PSEUDO_MAP_IDX:
                                 if (bpfptr_is_null(env->fd_array)) {
                                         verbose(env, "fd_idx without fd_array is invalid\n");
                                         return -EPROTO;
                                 }
                                 if (copy_from_bpfptr_offset(&fd, env->fd_array,
                                                             insn[0].imm * sizeof(fd),
                                                             sizeof(fd)))
                                         return -EFAULT;
                                 break;
                         default:
                                 fd = insn[0].imm;
                                 break;
                         }
 
                         f = fdget(fd);
                         map = __bpf_map_get(f);
                         if (IS_ERR(map)) {
                                 verbose(env, "fd %d is not pointing to valid bpf_map\n", fd);
                                 return PTR_ERR(map);
                         }
 
                         err = check_map_prog_compatibility(env, map, env->prog);
                         if (err) {
                                 fdput(f);
                                 return err;
                         }
 
                         aux = &env->insn_aux_data[i];
                         if (insn[0].src_reg == BPF_PSEUDO_MAP_FD ||
                             insn[0].src_reg == BPF_PSEUDO_MAP_IDX) {
                                 addr = (unsigned long)map;
                         } else {
                                 u32 off = insn[1].imm;
 
                                 if (off >= BPF_MAX_VAR_OFF) {
                                         verbose(env, "direct value offset of %u is not allowed\n", off);
                                         fdput(f);
                                         return -EINVAL;
                                 }
 
                                 if (!map->ops->map_direct_value_addr) {
                                         verbose(env, "no direct value access support for this map type\n");
                                         fdput(f);
                                         return -EINVAL;
                                 }
 
                                 err = map->ops->map_direct_value_addr(map, &addr, off);
                                 if (err) {
                                         verbose(env, "invalid access to map value pointer, value_size=%u off=%u\n",
                                                 map->value_size, off);
                                         fdput(f);
                                         return err;
                                 }
 
                                 aux->map_off = off;
                                 addr += off;
                         }
 
                         insn[0].imm = (u32)addr;
                         insn[1].imm = addr >> 32;
 
                         /* check whether we recorded this map already */
                         for (j = 0; j < env->used_map_cnt; j++) {
                                 if (env->used_maps[j] == map) {
                                         aux->map_index = j;
                                         fdput(f);
                                         goto next_insn;
                                 }
                         }
 
                         if (env->used_map_cnt >= MAX_USED_MAPS) {
                                 verbose(env, "The total number of maps per program has reached the limit of %u\n",
                                         MAX_USED_MAPS);
                                 fdput(f);
                                 return -E2BIG;
                         }
 
                         if (env->prog->sleepable)
                                 atomic64_inc(&map->sleepable_refcnt);
                         /* hold the map. If the program is rejected by verifier,
                          * the map will be released by release_maps() or it
                          * will be used by the valid program until it's unloaded
                          * and all maps are released in bpf_free_used_maps()
                          */
                         bpf_map_inc(map);
 
                         aux->map_index = env->used_map_cnt;
                         env->used_maps[env->used_map_cnt++] = map;
 
                         if (bpf_map_is_cgroup_storage(map) &&
                             bpf_cgroup_storage_assign(env->prog->aux, map)) {
                                 verbose(env, "only one cgroup storage of each type is allowed\n");
                                 fdput(f);
                                 return -EBUSY;
                         }
                         if (map->map_type == BPF_MAP_TYPE_ARENA) {
                                 if (env->prog->aux->arena) {
                                         verbose(env, "Only one arena per program\n");
                                         fdput(f);
                                         return -EBUSY;
                                 }
                                 if (!env->allow_ptr_leaks || !env->bpf_capable) {
                                         verbose(env, "CAP_BPF and CAP_PERFMON are required to use arena\n");
                                         fdput(f);
                                         return -EPERM;
                                 }
                                 if (!env->prog->jit_requested) {
                                         verbose(env, "JIT is required to use arena\n");
                                         fdput(f);
                                         return -EOPNOTSUPP;
                                 }
                                 if (!bpf_jit_supports_arena()) {
                                         verbose(env, "JIT doesn't support arena\n");
                                         fdput(f);
                                         return -EOPNOTSUPP;
                                 }
                                 env->prog->aux->arena = (void *)map;
                                 if (!bpf_arena_get_user_vm_start(env->prog->aux->arena)) {
                                         verbose(env, "arena's user address must be set via map_extra or mmap()\n");
                                         fdput(f);
                                         return -EINVAL;
                                 }
                         }
 
                         fdput(f);
 next_insn:
                         insn++;
                         i++;
                         continue;
                 }
 
                 /* Basic sanity check before we invest more work here. */
                 if (!bpf_opcode_in_insntable(insn->code)) {
                         verbose(env, "unknown opcode %02x\n", insn->code);
                         return -EINVAL;
                 }
         }
 
         /* now all pseudo BPF_LD_IMM64 instructions load valid
          * 'struct bpf_map *' into a register instead of user map_fd.
          * These pointers will be used later by verifier to validate map access.
          */
         return 0;
 }
 
 /* drop refcnt of maps used by the rejected program */
 static void release_maps(struct bpf_verifier_env *env)
 {
         __bpf_free_used_maps(env->prog->aux, env->used_maps,
                              env->used_map_cnt);
 }
 
 /* drop refcnt of maps used by the rejected program */
 static void release_btfs(struct bpf_verifier_env *env)
 {
         __bpf_free_used_btfs(env->used_btfs, env->used_btf_cnt);
 }
 
 /* convert pseudo BPF_LD_IMM64 into generic BPF_LD_IMM64 */
 static void convert_pseudo_ld_imm64(struct bpf_verifier_env *env)
 {
         struct bpf_insn *insn = env->prog->insnsi;
         int insn_cnt = env->prog->len;
         int i;
 
         for (i = 0; i < insn_cnt; i++, insn++) {
                 if (insn->code != (BPF_LD | BPF_IMM | BPF_DW))
                         continue;
                 if (insn->src_reg == BPF_PSEUDO_FUNC)
                         continue;
                 insn->src_reg = 0;
         }
 }
 
 /* single env->prog->insni[off] instruction was replaced with the range
  * insni[off, off + cnt).  Adjust corresponding insn_aux_data by copying
  * [0, off) and [off, end) to new locations, so the patched range stays zero
  */
 static void adjust_insn_aux_data(struct bpf_verifier_env *env,
                                  struct bpf_insn_aux_data *new_data,
                                  struct bpf_prog *new_prog, u32 off, u32 cnt)
 {
         struct bpf_insn_aux_data *old_data = env->insn_aux_data;
         struct bpf_insn *insn = new_prog->insnsi;
         u32 old_seen = old_data[off].seen;
         u32 prog_len;
         int i;
 
         /* aux info at OFF always needs adjustment, no matter fast path
          * (cnt == 1) is taken or not. There is no guarantee INSN at OFF is the
          * original insn at old prog.
          */
         old_data[off].zext_dst = insn_has_def32(env, insn + off + cnt - 1);
 
         if (cnt == 1)
                 return;
         prog_len = new_prog->len;
 
         memcpy(new_data, old_data, sizeof(struct bpf_insn_aux_data) * off);
         memcpy(new_data + off + cnt - 1, old_data + off,
                sizeof(struct bpf_insn_aux_data) * (prog_len - off - cnt + 1));
         for (i = off; i < off + cnt - 1; i++) {
                 /* Expand insni[off]'s seen count to the patched range. */
                 new_data[i].seen = old_seen;
                 new_data[i].zext_dst = insn_has_def32(env, insn + i);
         }
         env->insn_aux_data = new_data;
         vfree(old_data);
 }
 
 static void adjust_subprog_starts(struct bpf_verifier_env *env, u32 off, u32 len)
 {
         int i;
 
         if (len == 1)
                 return;
         /* NOTE: fake 'exit' subprog should be updated as well. */
         for (i = 0; i <= env->subprog_cnt; i++) {
                 if (env->subprog_info[i].start <= off)
                         continue;
                 env->subprog_info[i].start += len - 1;
         }
 }
 
 static void adjust_poke_descs(struct bpf_prog *prog, u32 off, u32 len)
 {
         struct bpf_jit_poke_descriptor *tab = prog->aux->poke_tab;
         int i, sz = prog->aux->size_poke_tab;
         struct bpf_jit_poke_descriptor *desc;
 
         for (i = 0; i < sz; i++) {
                 desc = &tab[i];
                 if (desc->insn_idx <= off)
                         continue;
                 desc->insn_idx += len - 1;
         }
 }
 
 static struct bpf_prog *bpf_patch_insn_data(struct bpf_verifier_env *env, u32 off,
                                             const struct bpf_insn *patch, u32 len)
 {
         struct bpf_prog *new_prog;
         struct bpf_insn_aux_data *new_data = NULL;
 
         if (len > 1) {
                 new_data = vzalloc(array_size(env->prog->len + len - 1,
                                               sizeof(struct bpf_insn_aux_data)));
                 if (!new_data)
                         return NULL;
         }
 
         new_prog = bpf_patch_insn_single(env->prog, off, patch, len);
         if (IS_ERR(new_prog)) {
                 if (PTR_ERR(new_prog) == -ERANGE)
                         verbose(env,
                                 "insn %d cannot be patched due to 16-bit range\n",
                                 env->insn_aux_data[off].orig_idx);
                 vfree(new_data);
                 return NULL;
         }
         adjust_insn_aux_data(env, new_data, new_prog, off, len);
         adjust_subprog_starts(env, off, len);
         adjust_poke_descs(new_prog, off, len);
         return new_prog;
 }
 
 /*
  * For all jmp insns in a given 'prog' that point to 'tgt_idx' insn adjust the
  * jump offset by 'delta'.
  */
 static int adjust_jmp_off(struct bpf_prog *prog, u32 tgt_idx, u32 delta)
 {
         struct bpf_insn *insn = prog->insnsi;
         u32 insn_cnt = prog->len, i;
         s32 imm;
         s16 off;
 
         for (i = 0; i < insn_cnt; i++, insn++) {
                 u8 code = insn->code;
 
                 if ((BPF_CLASS(code) != BPF_JMP && BPF_CLASS(code) != BPF_JMP32) ||
                     BPF_OP(code) == BPF_CALL || BPF_OP(code) == BPF_EXIT)
                         continue;
 
                 if (insn->code == (BPF_JMP32 | BPF_JA)) {
                         if (i + 1 + insn->imm != tgt_idx)
                                 continue;
                         if (check_add_overflow(insn->imm, delta, &imm))
                                 return -ERANGE;
                         insn->imm = imm;
                 } else {
                         if (i + 1 + insn->off != tgt_idx)
                                 continue;
                         if (check_add_overflow(insn->off, delta, &off))
                                 return -ERANGE;
                         insn->off = off;
                 }
         }
         return 0;
 }
 
 static int adjust_subprog_starts_after_remove(struct bpf_verifier_env *env,
                                               u32 off, u32 cnt)
 {
         int i, j;
 
         /* find first prog starting at or after off (first to remove) */
         for (i = 0; i < env->subprog_cnt; i++)
                 if (env->subprog_info[i].start >= off)
                         break;
         /* find first prog starting at or after off + cnt (first to stay) */
         for (j = i; j < env->subprog_cnt; j++)
                 if (env->subprog_info[j].start >= off + cnt)
                         break;
         /* if j doesn't start exactly at off + cnt, we are just removing
          * the front of previous prog
          */
         if (env->subprog_info[j].start != off + cnt)
                 j--;
 
         if (j > i) {
                 struct bpf_prog_aux *aux = env->prog->aux;
                 int move;
 
                 /* move fake 'exit' subprog as well */
                 move = env->subprog_cnt + 1 - j;
 
                 memmove(env->subprog_info + i,
                         env->subprog_info + j,
                         sizeof(*env->subprog_info) * move);
                 env->subprog_cnt -= j - i;
 
                 /* remove func_info */
                 if (aux->func_info) {
                         move = aux->func_info_cnt - j;
 
                         memmove(aux->func_info + i,
                                 aux->func_info + j,
                                 sizeof(*aux->func_info) * move);
                         aux->func_info_cnt -= j - i;
                         /* func_info->insn_off is set after all code rewrites,
                          * in adjust_btf_func() - no need to adjust
                          */
                 }
         } else {
                 /* convert i from "first prog to remove" to "first to adjust" */
                 if (env->subprog_info[i].start == off)
                         i++;
         }
 
         /* update fake 'exit' subprog as well */
         for (; i <= env->subprog_cnt; i++)
                 env->subprog_info[i].start -= cnt;
 
         return 0;
 }
 
 static int bpf_adj_linfo_after_remove(struct bpf_verifier_env *env, u32 off,
                                       u32 cnt)
 {
         struct bpf_prog *prog = env->prog;
         u32 i, l_off, l_cnt, nr_linfo;
         struct bpf_line_info *linfo;
 
         nr_linfo = prog->aux->nr_linfo;
         if (!nr_linfo)
                 return 0;
 
         linfo = prog->aux->linfo;
 
         /* find first line info to remove, count lines to be removed */
         for (i = 0; i < nr_linfo; i++)
                 if (linfo[i].insn_off >= off)
                         break;
 
         l_off = i;
         l_cnt = 0;
         for (; i < nr_linfo; i++)
                 if (linfo[i].insn_off < off + cnt)
                         l_cnt++;
                 else
                         break;
 
         /* First live insn doesn't match first live linfo, it needs to "inherit"
          * last removed linfo.  prog is already modified, so prog->len == off
          * means no live instructions after (tail of the program was removed).
          */
         if (prog->len != off && l_cnt &&
             (i == nr_linfo || linfo[i].insn_off != off + cnt)) {
                 l_cnt--;
                 linfo[--i].insn_off = off + cnt;
         }
 
         /* remove the line info which refer to the removed instructions */
         if (l_cnt) {
                 memmove(linfo + l_off, linfo + i,
                         sizeof(*linfo) * (nr_linfo - i));
 
                 prog->aux->nr_linfo -= l_cnt;
                 nr_linfo = prog->aux->nr_linfo;
         }
 
         /* pull all linfo[i].insn_off >= off + cnt in by cnt */
         for (i = l_off; i < nr_linfo; i++)
                 linfo[i].insn_off -= cnt;
 
         /* fix up all subprogs (incl. 'exit') which start >= off */
         for (i = 0; i <= env->subprog_cnt; i++)
                 if (env->subprog_info[i].linfo_idx > l_off) {
                         /* program may have started in the removed region but
                          * may not be fully removed
                          */
                         if (env->subprog_info[i].linfo_idx >= l_off + l_cnt)
                                 env->subprog_info[i].linfo_idx -= l_cnt;
                         else
                                 env->subprog_info[i].linfo_idx = l_off;
                 }
 
         return 0;
 }
 
 static int verifier_remove_insns(struct bpf_verifier_env *env, u32 off, u32 cnt)
 {
         struct bpf_insn_aux_data *aux_data = env->insn_aux_data;
         unsigned int orig_prog_len = env->prog->len;
         int err;
 
         if (bpf_prog_is_offloaded(env->prog->aux))
                 bpf_prog_offload_remove_insns(env, off, cnt);
 
         err = bpf_remove_insns(env->prog, off, cnt);
         if (err)
                 return err;
 
         err = adjust_subprog_starts_after_remove(env, off, cnt);
         if (err)
                 return err;
 
         err = bpf_adj_linfo_after_remove(env, off, cnt);
         if (err)
                 return err;
 
         memmove(aux_data + off, aux_data + off + cnt,
                 sizeof(*aux_data) * (orig_prog_len - off - cnt));
 
         return 0;
 }
 
 /* The verifier does more data flow analysis than llvm and will not
  * explore branches that are dead at run time. Malicious programs can
  * have dead code too. Therefore replace all dead at-run-time code
  * with 'ja -1'.
  *
  * Just nops are not optimal, e.g. if they would sit at the end of the
  * program and through another bug we would manage to jump there, then
  * we'd execute beyond program memory otherwise. Returning exception
  * code also wouldn't work since we can have subprogs where the dead
  * code could be located.
  */
 static void sanitize_dead_code(struct bpf_verifier_env *env)
 {
         struct bpf_insn_aux_data *aux_data = env->insn_aux_data;
         struct bpf_insn trap = BPF_JMP_IMM(BPF_JA, 0, 0, -1);
         struct bpf_insn *insn = env->prog->insnsi;
         const int insn_cnt = env->prog->len;
         int i;
 
         for (i = 0; i < insn_cnt; i++) {
                 if (aux_data[i].seen)
                         continue;
                 memcpy(insn + i, &trap, sizeof(trap));
                 aux_data[i].zext_dst = false;
         }
 }
 
 static bool insn_is_cond_jump(u8 code)
 {
         u8 op;
 
         op = BPF_OP(code);
         if (BPF_CLASS(code) == BPF_JMP32)
                 return op != BPF_JA;
 
         if (BPF_CLASS(code) != BPF_JMP)
                 return false;
 
         return op != BPF_JA && op != BPF_EXIT && op != BPF_CALL;
 }
 
 static void opt_hard_wire_dead_code_branches(struct bpf_verifier_env *env)
 {
         struct bpf_insn_aux_data *aux_data = env->insn_aux_data;
         struct bpf_insn ja = BPF_JMP_IMM(BPF_JA, 0, 0, 0);
         struct bpf_insn *insn = env->prog->insnsi;
         const int insn_cnt = env->prog->len;
         int i;
 
         for (i = 0; i < insn_cnt; i++, insn++) {
                 if (!insn_is_cond_jump(insn->code))
                         continue;
 
                 if (!aux_data[i + 1].seen)
                         ja.off = insn->off;
                 else if (!aux_data[i + 1 + insn->off].seen)
                         ja.off = 0;
                 else
                         continue;
 
                 if (bpf_prog_is_offloaded(env->prog->aux))
                         bpf_prog_offload_replace_insn(env, i, &ja);
 
                 memcpy(insn, &ja, sizeof(ja));
         }
 }
 
 static int opt_remove_dead_code(struct bpf_verifier_env *env)
 {
         struct bpf_insn_aux_data *aux_data = env->insn_aux_data;
         int insn_cnt = env->prog->len;
         int i, err;
 
         for (i = 0; i < insn_cnt; i++) {
                 int j;
 
                 j = 0;
                 while (i + j < insn_cnt && !aux_data[i + j].seen)
                         j++;
                 if (!j)
                         continue;
 
                 err = verifier_remove_insns(env, i, j);
                 if (err)
                         return err;
                 insn_cnt = env->prog->len;
         }
 
         return 0;
 }
 
 static int opt_remove_nops(struct bpf_verifier_env *env)
 {
         const struct bpf_insn ja = BPF_JMP_IMM(BPF_JA, 0, 0, 0);
         struct bpf_insn *insn = env->prog->insnsi;
         int insn_cnt = env->prog->len;
         int i, err;
 
         for (i = 0; i < insn_cnt; i++) {
                 if (memcmp(&insn[i], &ja, sizeof(ja)))
                         continue;
 
                 err = verifier_remove_insns(env, i, 1);
                 if (err)
                         return err;
                 insn_cnt--;
                 i--;
         }
 
         return 0;
 }
 
 static int opt_subreg_zext_lo32_rnd_hi32(struct bpf_verifier_env *env,
                                          const union bpf_attr *attr)
 {
         struct bpf_insn *patch, zext_patch[2], rnd_hi32_patch[4];
         struct bpf_insn_aux_data *aux = env->insn_aux_data;
         int i, patch_len, delta = 0, len = env->prog->len;
         struct bpf_insn *insns = env->prog->insnsi;
         struct bpf_prog *new_prog;
         bool rnd_hi32;
 
         rnd_hi32 = attr->prog_flags & BPF_F_TEST_RND_HI32;
         zext_patch[1] = BPF_ZEXT_REG(0);
         rnd_hi32_patch[1] = BPF_ALU64_IMM(BPF_MOV, BPF_REG_AX, 0);
         rnd_hi32_patch[2] = BPF_ALU64_IMM(BPF_LSH, BPF_REG_AX, 32);
         rnd_hi32_patch[3] = BPF_ALU64_REG(BPF_OR, 0, BPF_REG_AX);
         for (i = 0; i < len; i++) {
                 int adj_idx = i + delta;
                 struct bpf_insn insn;
                 int load_reg;
 
                 insn = insns[adj_idx];
                 load_reg = insn_def_regno(&insn);
                 if (!aux[adj_idx].zext_dst) {
                         u8 code, class;
                         u32 imm_rnd;
 
                         if (!rnd_hi32)
                                 continue;
 
                         code = insn.code;
                         class = BPF_CLASS(code);
                         if (load_reg == -1)
                                 continue;
 
                         /* NOTE: arg "reg" (the fourth one) is only used for
                          *       BPF_STX + SRC_OP, so it is safe to pass NULL
                          *       here.
                          */
                         if (is_reg64(env, &insn, load_reg, NULL, DST_OP)) {
                                 if (class == BPF_LD &&
                                     BPF_MODE(code) == BPF_IMM)
                                         i++;
                                 continue;
                         }
 
                         /* ctx load could be transformed into wider load. */
                         if (class == BPF_LDX &&
                             aux[adj_idx].ptr_type == PTR_TO_CTX)
                                 continue;
 
                         imm_rnd = get_random_u32();
                         rnd_hi32_patch[0] = insn;
                         rnd_hi32_patch[1].imm = imm_rnd;
                         rnd_hi32_patch[3].dst_reg = load_reg;
                         patch = rnd_hi32_patch;
                         patch_len = 4;
                         goto apply_patch_buffer;
                 }
 
                 /* Add in an zero-extend instruction if a) the JIT has requested
                  * it or b) it's a CMPXCHG.
                  *
                  * The latter is because: BPF_CMPXCHG always loads a value into
                  * R0, therefore always zero-extends. However some archs'
                  * equivalent instruction only does this load when the
                  * comparison is successful. This detail of CMPXCHG is
                  * orthogonal to the general zero-extension behaviour of the
                  * CPU, so it's treated independently of bpf_jit_needs_zext.
                  */
                 if (!bpf_jit_needs_zext() && !is_cmpxchg_insn(&insn))
                         continue;
 
                 /* Zero-extension is done by the caller. */
                 if (bpf_pseudo_kfunc_call(&insn))
                         continue;
 
                 if (WARN_ON(load_reg == -1)) {
                         verbose(env, "verifier bug. zext_dst is set, but no reg is defined\n");
                         return -EFAULT;
                 }
 
                 zext_patch[0] = insn;
                 zext_patch[1].dst_reg = load_reg;
                 zext_patch[1].src_reg = load_reg;
                 patch = zext_patch;
                 patch_len = 2;
 apply_patch_buffer:
                 new_prog = bpf_patch_insn_data(env, adj_idx, patch, patch_len);
                 if (!new_prog)
                         return -ENOMEM;
                 env->prog = new_prog;
                 insns = new_prog->insnsi;
                 aux = env->insn_aux_data;
                 delta += patch_len - 1;
         }
 
         return 0;
 }
 
 /* convert load instructions that access fields of a context type into a
  * sequence of instructions that access fields of the underlying structure:
  *     struct __sk_buff    -> struct sk_buff
  *     struct bpf_sock_ops -> struct sock
  */
 static int convert_ctx_accesses(struct bpf_verifier_env *env)
 {
         const struct bpf_verifier_ops *ops = env->ops;
         int i, cnt, size, ctx_field_size, delta = 0;
         const int insn_cnt = env->prog->len;
         struct bpf_insn insn_buf[16], *insn;
         u32 target_size, size_default, off;
         struct bpf_prog *new_prog;
         enum bpf_access_type type;
         bool is_narrower_load;
 
         if (ops->gen_prologue || env->seen_direct_write) {
                 if (!ops->gen_prologue) {
                         verbose(env, "bpf verifier is misconfigured\n");
                         return -EINVAL;
                 }
                 cnt = ops->gen_prologue(insn_buf, env->seen_direct_write,
                                         env->prog);
                 if (cnt >= ARRAY_SIZE(insn_buf)) {
                         verbose(env, "bpf verifier is misconfigured\n");
                         return -EINVAL;
                 } else if (cnt) {
                         new_prog = bpf_patch_insn_data(env, 0, insn_buf, cnt);
                         if (!new_prog)
                                 return -ENOMEM;
 
                         env->prog = new_prog;
                         delta += cnt - 1;
                 }
         }
 
         if (bpf_prog_is_offloaded(env->prog->aux))
                 return 0;
 
         insn = env->prog->insnsi + delta;
 
         for (i = 0; i < insn_cnt; i++, insn++) {
                 bpf_convert_ctx_access_t convert_ctx_access;
                 u8 mode;
 
                 if (insn->code == (BPF_LDX | BPF_MEM | BPF_B) ||
                     insn->code == (BPF_LDX | BPF_MEM | BPF_H) ||
                     insn->code == (BPF_LDX | BPF_MEM | BPF_W) ||
                     insn->code == (BPF_LDX | BPF_MEM | BPF_DW) ||
                     insn->code == (BPF_LDX | BPF_MEMSX | BPF_B) ||
                     insn->code == (BPF_LDX | BPF_MEMSX | BPF_H) ||
                     insn->code == (BPF_LDX | BPF_MEMSX | BPF_W)) {
                         type = BPF_READ;
                 } else if (insn->code == (BPF_STX | BPF_MEM | BPF_B) ||
                            insn->code == (BPF_STX | BPF_MEM | BPF_H) ||
                            insn->code == (BPF_STX | BPF_MEM | BPF_W) ||
                            insn->code == (BPF_STX | BPF_MEM | BPF_DW) ||
                            insn->code == (BPF_ST | BPF_MEM | BPF_B) ||
                            insn->code == (BPF_ST | BPF_MEM | BPF_H) ||
                            insn->code == (BPF_ST | BPF_MEM | BPF_W) ||
                            insn->code == (BPF_ST | BPF_MEM | BPF_DW)) {
                         type = BPF_WRITE;
                 } else if ((insn->code == (BPF_STX | BPF_ATOMIC | BPF_W) ||
                             insn->code == (BPF_STX | BPF_ATOMIC | BPF_DW)) &&
                            env->insn_aux_data[i + delta].ptr_type == PTR_TO_ARENA) {
                         insn->code = BPF_STX | BPF_PROBE_ATOMIC | BPF_SIZE(insn->code);
                         env->prog->aux->num_exentries++;
                         continue;
                 } else {
                         continue;
                 }
 
                 if (type == BPF_WRITE &&
                     env->insn_aux_data[i + delta].sanitize_stack_spill) {
                         struct bpf_insn patch[] = {
                                 *insn,
                                 BPF_ST_NOSPEC(),
                         };
 
                         cnt = ARRAY_SIZE(patch);
                         new_prog = bpf_patch_insn_data(env, i + delta, patch, cnt);
                         if (!new_prog)
                                 return -ENOMEM;
 
                         delta    += cnt - 1;
                         env->prog = new_prog;
                         insn      = new_prog->insnsi + i + delta;
                         continue;
                 }
 
                 switch ((int)env->insn_aux_data[i + delta].ptr_type) {
                 case PTR_TO_CTX:
                         if (!ops->convert_ctx_access)
                                 continue;
                         convert_ctx_access = ops->convert_ctx_access;
                         break;
                 case PTR_TO_SOCKET:
                 case PTR_TO_SOCK_COMMON:
                         convert_ctx_access = bpf_sock_convert_ctx_access;
                         break;
                 case PTR_TO_TCP_SOCK:
                         convert_ctx_access = bpf_tcp_sock_convert_ctx_access;
                         break;
                 case PTR_TO_XDP_SOCK:
                         convert_ctx_access = bpf_xdp_sock_convert_ctx_access;
                         break;
                 case PTR_TO_BTF_ID:
                 case PTR_TO_BTF_ID | PTR_UNTRUSTED:
                 /* PTR_TO_BTF_ID | MEM_ALLOC always has a valid lifetime, unlike
                  * PTR_TO_BTF_ID, and an active ref_obj_id, but the same cannot
                  * be said once it is marked PTR_UNTRUSTED, hence we must handle
                  * any faults for loads into such types. BPF_WRITE is disallowed
                  * for this case.
                  */
                 case PTR_TO_BTF_ID | MEM_ALLOC | PTR_UNTRUSTED:
                         if (type == BPF_READ) {
                                 if (BPF_MODE(insn->code) == BPF_MEM)
                                         insn->code = BPF_LDX | BPF_PROBE_MEM |
                                                      BPF_SIZE((insn)->code);
                                 else
                                         insn->code = BPF_LDX | BPF_PROBE_MEMSX |
                                                      BPF_SIZE((insn)->code);
                                 env->prog->aux->num_exentries++;
                         }
                         continue;
                 case PTR_TO_ARENA:
                         if (BPF_MODE(insn->code) == BPF_MEMSX) {
                                 verbose(env, "sign extending loads from arena are not supported yet\n");
                                 return -EOPNOTSUPP;
                         }
                         insn->code = BPF_CLASS(insn->code) | BPF_PROBE_MEM32 | BPF_SIZE(insn->code);
                         env->prog->aux->num_exentries++;
                         continue;
                 default:
                         continue;
                 }
 
                 ctx_field_size = env->insn_aux_data[i + delta].ctx_field_size;
                 size = BPF_LDST_BYTES(insn);
                 mode = BPF_MODE(insn->code);
 
                 /* If the read access is a narrower load of the field,
                  * convert to a 4/8-byte load, to minimum program type specific
                  * convert_ctx_access changes. If conversion is successful,
                  * we will apply proper mask to the result.
                  */
                 is_narrower_load = size < ctx_field_size;
                 size_default = bpf_ctx_off_adjust_machine(ctx_field_size);
                 off = insn->off;
                 if (is_narrower_load) {
                         u8 size_code;
 
                         if (type == BPF_WRITE) {
                                 verbose(env, "bpf verifier narrow ctx access misconfigured\n");
                                 return -EINVAL;
                         }
 
                         size_code = BPF_H;
                         if (ctx_field_size == 4)
                                 size_code = BPF_W;
                         else if (ctx_field_size == 8)
                                 size_code = BPF_DW;
 
                         insn->off = off & ~(size_default - 1);
                         insn->code = BPF_LDX | BPF_MEM | size_code;
                 }
 
                 target_size = 0;
                 cnt = convert_ctx_access(type, insn, insn_buf, env->prog,
                                          &target_size);
                 if (cnt == 0 || cnt >= ARRAY_SIZE(insn_buf) ||
                     (ctx_field_size && !target_size)) {
                         verbose(env, "bpf verifier is misconfigured\n");
                         return -EINVAL;
                 }
 
                 if (is_narrower_load && size < target_size) {
                         u8 shift = bpf_ctx_narrow_access_offset(
                                 off, size, size_default) * 8;
                         if (shift && cnt + 1 >= ARRAY_SIZE(insn_buf)) {
                                 verbose(env, "bpf verifier narrow ctx load misconfigured\n");
                                 return -EINVAL;
                         }
                         if (ctx_field_size <= 4) {
                                 if (shift)
                                         insn_buf[cnt++] = BPF_ALU32_IMM(BPF_RSH,
                                                                         insn->dst_reg,
                                                                         shift);
                                 insn_buf[cnt++] = BPF_ALU32_IMM(BPF_AND, insn->dst_reg,
                                                                 (1 << size * 8) - 1);
                         } else {
                                 if (shift)
                                         insn_buf[cnt++] = BPF_ALU64_IMM(BPF_RSH,
                                                                         insn->dst_reg,
                                                                         shift);
                                 insn_buf[cnt++] = BPF_ALU32_IMM(BPF_AND, insn->dst_reg,
                                                                 (1ULL << size * 8) - 1);
                         }
                 }
                 if (mode == BPF_MEMSX)
                         insn_buf[cnt++] = BPF_RAW_INSN(BPF_ALU64 | BPF_MOV | BPF_X,
                                                        insn->dst_reg, insn->dst_reg,
                                                        size * 8, 0);
 
                 new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
                 if (!new_prog)
                         return -ENOMEM;
 
                 delta += cnt - 1;
 
                 /* keep walking new program and skip insns we just inserted */
                 env->prog = new_prog;
                 insn      = new_prog->insnsi + i + delta;
         }
 
         return 0;
 }
 
 static int jit_subprogs(struct bpf_verifier_env *env)
 {
         struct bpf_prog *prog = env->prog, **func, *tmp;
         int i, j, subprog_start, subprog_end = 0, len, subprog;
         struct bpf_map *map_ptr;
         struct bpf_insn *insn;
         void *old_bpf_func;
         int err, num_exentries;
 
         if (env->subprog_cnt <= 1)
                 return 0;
 
         for (i = 0, insn = prog->insnsi; i < prog->len; i++, insn++) {
                 if (!bpf_pseudo_func(insn) && !bpf_pseudo_call(insn))
                         continue;
 
                 /* Upon error here we cannot fall back to interpreter but
                  * need a hard reject of the program. Thus -EFAULT is
                  * propagated in any case.
                  */
                 subprog = find_subprog(env, i + insn->imm + 1);
                 if (subprog < 0) {
                         WARN_ONCE(1, "verifier bug. No program starts at insn %d\n",
                                   i + insn->imm + 1);
                         return -EFAULT;
                 }
                 /* temporarily remember subprog id inside insn instead of
                  * aux_data, since next loop will split up all insns into funcs
                  */
                 insn->off = subprog;
                 /* remember original imm in case JIT fails and fallback
                  * to interpreter will be needed
                  */
                 env->insn_aux_data[i].call_imm = insn->imm;
                 /* point imm to __bpf_call_base+1 from JITs point of view */
                 insn->imm = 1;
                 if (bpf_pseudo_func(insn)) {
 #if defined(MODULES_VADDR)
                         u64 addr = MODULES_VADDR;
 #else
                         u64 addr = VMALLOC_START;
 #endif
                         /* jit (e.g. x86_64) may emit fewer instructions
                          * if it learns a u32 imm is the same as a u64 imm.
                          * Set close enough to possible prog address.
                          */
                         insn[0].imm = (u32)addr;
                         insn[1].imm = addr >> 32;
                 }
         }
 
         err = bpf_prog_alloc_jited_linfo(prog);
         if (err)
                 goto out_undo_insn;
 
         err = -ENOMEM;
         func = kcalloc(env->subprog_cnt, sizeof(prog), GFP_KERNEL);
         if (!func)
                 goto out_undo_insn;
 
         for (i = 0; i < env->subprog_cnt; i++) {
                 subprog_start = subprog_end;
                 subprog_end = env->subprog_info[i + 1].start;
 
                 len = subprog_end - subprog_start;
                 /* bpf_prog_run() doesn't call subprogs directly,
                  * hence main prog stats include the runtime of subprogs.
                  * subprogs don't have IDs and not reachable via prog_get_next_id
                  * func[i]->stats will never be accessed and stays NULL
                  */
                 func[i] = bpf_prog_alloc_no_stats(bpf_prog_size(len), GFP_USER);
                 if (!func[i])
                         goto out_free;
                 memcpy(func[i]->insnsi, &prog->insnsi[subprog_start],
                        len * sizeof(struct bpf_insn));
                 func[i]->type = prog->type;
                 func[i]->len = len;
                 if (bpf_prog_calc_tag(func[i]))
                         goto out_free;
                 func[i]->is_func = 1;
                 func[i]->sleepable = prog->sleepable;
                 func[i]->aux->func_idx = i;
                 /* Below members will be freed only at prog->aux */
                 func[i]->aux->btf = prog->aux->btf;
                 func[i]->aux->func_info = prog->aux->func_info;
                 func[i]->aux->func_info_cnt = prog->aux->func_info_cnt;
                 func[i]->aux->poke_tab = prog->aux->poke_tab;
                 func[i]->aux->size_poke_tab = prog->aux->size_poke_tab;
 
                 for (j = 0; j < prog->aux->size_poke_tab; j++) {
                         struct bpf_jit_poke_descriptor *poke;
 
                         poke = &prog->aux->poke_tab[j];
                         if (poke->insn_idx < subprog_end &&
                             poke->insn_idx >= subprog_start)
                                 poke->aux = func[i]->aux;
                 }
 
                 func[i]->aux->name[0] = 'F';
                 func[i]->aux->stack_depth = env->subprog_info[i].stack_depth;
                 func[i]->jit_requested = 1;
                 func[i]->blinding_requested = prog->blinding_requested;
                 func[i]->aux->kfunc_tab = prog->aux->kfunc_tab;
                 func[i]->aux->kfunc_btf_tab = prog->aux->kfunc_btf_tab;
                 func[i]->aux->linfo = prog->aux->linfo;
                 func[i]->aux->nr_linfo = prog->aux->nr_linfo;
                 func[i]->aux->jited_linfo = prog->aux->jited_linfo;
                 func[i]->aux->linfo_idx = env->subprog_info[i].linfo_idx;
                 func[i]->aux->arena = prog->aux->arena;
                 num_exentries = 0;
                 insn = func[i]->insnsi;
                 for (j = 0; j < func[i]->len; j++, insn++) {
                         if (BPF_CLASS(insn->code) == BPF_LDX &&
                             (BPF_MODE(insn->code) == BPF_PROBE_MEM ||
                              BPF_MODE(insn->code) == BPF_PROBE_MEM32 ||
                              BPF_MODE(insn->code) == BPF_PROBE_MEMSX))
                                 num_exentries++;
                         if ((BPF_CLASS(insn->code) == BPF_STX ||
                              BPF_CLASS(insn->code) == BPF_ST) &&
                              BPF_MODE(insn->code) == BPF_PROBE_MEM32)
                                 num_exentries++;
                         if (BPF_CLASS(insn->code) == BPF_STX &&
                              BPF_MODE(insn->code) == BPF_PROBE_ATOMIC)
                                 num_exentries++;
                 }
                 func[i]->aux->num_exentries = num_exentries;
                 func[i]->aux->tail_call_reachable = env->subprog_info[i].tail_call_reachable;
                 func[i]->aux->exception_cb = env->subprog_info[i].is_exception_cb;
                 if (!i)
                         func[i]->aux->exception_boundary = env->seen_exception;
                 func[i] = bpf_int_jit_compile(func[i]);
                 if (!func[i]->jited) {
                         err = -ENOTSUPP;
                         goto out_free;
                 }
                 cond_resched();
         }
 
         /* at this point all bpf functions were successfully JITed
          * now populate all bpf_calls with correct addresses and
          * run last pass of JIT
          */
         for (i = 0; i < env->subprog_cnt; i++) {
                 insn = func[i]->insnsi;
                 for (j = 0; j < func[i]->len; j++, insn++) {
                         if (bpf_pseudo_func(insn)) {
                                 subprog = insn->off;
                                 insn[0].imm = (u32)(long)func[subprog]->bpf_func;
                                 insn[1].imm = ((u64)(long)func[subprog]->bpf_func) >> 32;
                                 continue;
                         }
                         if (!bpf_pseudo_call(insn))
                                 continue;
                         subprog = insn->off;
                         insn->imm = BPF_CALL_IMM(func[subprog]->bpf_func);
                 }
 
                 /* we use the aux data to keep a list of the start addresses
                  * of the JITed images for each function in the program
                  *
                  * for some architectures, such as powerpc64, the imm field
                  * might not be large enough to hold the offset of the start
                  * address of the callee's JITed image from __bpf_call_base
                  *
                  * in such cases, we can lookup the start address of a callee
                  * by using its subprog id, available from the off field of
                  * the call instruction, as an index for this list
                  */
                 func[i]->aux->func = func;
                 func[i]->aux->func_cnt = env->subprog_cnt - env->hidden_subprog_cnt;
                 func[i]->aux->real_func_cnt = env->subprog_cnt;
         }
         for (i = 0; i < env->subprog_cnt; i++) {
                 old_bpf_func = func[i]->bpf_func;
                 tmp = bpf_int_jit_compile(func[i]);
                 if (tmp != func[i] || func[i]->bpf_func != old_bpf_func) {
                         verbose(env, "JIT doesn't support bpf-to-bpf calls\n");
                         err = -ENOTSUPP;
                         goto out_free;
                 }
                 cond_resched();
         }
 
         /* finally lock prog and jit images for all functions and
          * populate kallsysm. Begin at the first subprogram, since
          * bpf_prog_load will add the kallsyms for the main program.
          */
         for (i = 1; i < env->subprog_cnt; i++) {
                 err = bpf_prog_lock_ro(func[i]);
                 if (err)
                         goto out_free;
         }
 
         for (i = 1; i < env->subprog_cnt; i++)
                 bpf_prog_kallsyms_add(func[i]);
 
         /* Last step: make now unused interpreter insns from main
          * prog consistent for later dump requests, so they can
          * later look the same as if they were interpreted only.
          */
         for (i = 0, insn = prog->insnsi; i < prog->len; i++, insn++) {
                 if (bpf_pseudo_func(insn)) {
                         insn[0].imm = env->insn_aux_data[i].call_imm;
                         insn[1].imm = insn->off;
                         insn->off = 0;
                         continue;
                 }
                 if (!bpf_pseudo_call(insn))
                         continue;
                 insn->off = env->insn_aux_data[i].call_imm;
                 subprog = find_subprog(env, i + insn->off + 1);
                 insn->imm = subprog;
         }
 
         prog->jited = 1;
         prog->bpf_func = func[0]->bpf_func;
         prog->jited_len = func[0]->jited_len;
         prog->aux->extable = func[0]->aux->extable;
         prog->aux->num_exentries = func[0]->aux->num_exentries;
         prog->aux->func = func;
         prog->aux->func_cnt = env->subprog_cnt - env->hidden_subprog_cnt;
         prog->aux->real_func_cnt = env->subprog_cnt;
         prog->aux->bpf_exception_cb = (void *)func[env->exception_callback_subprog]->bpf_func;
         prog->aux->exception_boundary = func[0]->aux->exception_boundary;
         bpf_prog_jit_attempt_done(prog);
         return 0;
 out_free:
         /* We failed JIT'ing, so at this point we need to unregister poke
          * descriptors from subprogs, so that kernel is not attempting to
          * patch it anymore as we're freeing the subprog JIT memory.
          */
         for (i = 0; i < prog->aux->size_poke_tab; i++) {
                 map_ptr = prog->aux->poke_tab[i].tail_call.map;
                 map_ptr->ops->map_poke_untrack(map_ptr, prog->aux);
         }
         /* At this point we're guaranteed that poke descriptors are not
          * live anymore. We can just unlink its descriptor table as it's
          * released with the main prog.
          */
         for (i = 0; i < env->subprog_cnt; i++) {
                 if (!func[i])
                         continue;
                 func[i]->aux->poke_tab = NULL;
                 bpf_jit_free(func[i]);
         }
         kfree(func);
 out_undo_insn:
         /* cleanup main prog to be interpreted */
         prog->jit_requested = 0;
         prog->blinding_requested = 0;
         for (i = 0, insn = prog->insnsi; i < prog->len; i++, insn++) {
                 if (!bpf_pseudo_call(insn))
                         continue;
                 insn->off = 0;
                 insn->imm = env->insn_aux_data[i].call_imm;
         }
         bpf_prog_jit_attempt_done(prog);
         return err;
 }
 
 static int fixup_call_args(struct bpf_verifier_env *env)
 {
 #ifndef CONFIG_BPF_JIT_ALWAYS_ON
         struct bpf_prog *prog = env->prog;
         struct bpf_insn *insn = prog->insnsi;
         bool has_kfunc_call = bpf_prog_has_kfunc_call(prog);
         int i, depth;
 #endif
         int err = 0;
 
         if (env->prog->jit_requested &&
             !bpf_prog_is_offloaded(env->prog->aux)) {
                 err = jit_subprogs(env);
                 if (err == 0)
                         return 0;
                 if (err == -EFAULT)
                         return err;
         }
 #ifndef CONFIG_BPF_JIT_ALWAYS_ON
         if (has_kfunc_call) {
                 verbose(env, "calling kernel functions are not allowed in non-JITed programs\n");
                 return -EINVAL;
         }
         if (env->subprog_cnt > 1 && env->prog->aux->tail_call_reachable) {
                 /* When JIT fails the progs with bpf2bpf calls and tail_calls
                  * have to be rejected, since interpreter doesn't support them yet.
                  */
                 verbose(env, "tail_calls are not allowed in non-JITed programs with bpf-to-bpf calls\n");
                 return -EINVAL;
         }
         for (i = 0; i < prog->len; i++, insn++) {
                 if (bpf_pseudo_func(insn)) {
                         /* When JIT fails the progs with callback calls
                          * have to be rejected, since interpreter doesn't support them yet.
                          */
                         verbose(env, "callbacks are not allowed in non-JITed programs\n");
                         return -EINVAL;
                 }
 
                 if (!bpf_pseudo_call(insn))
                         continue;
                 depth = get_callee_stack_depth(env, insn, i);
                 if (depth < 0)
                         return depth;
                 bpf_patch_call_args(insn, depth);
         }
         err = 0;
 #endif
         return err;
 }
 
 /* replace a generic kfunc with a specialized version if necessary */
 static void specialize_kfunc(struct bpf_verifier_env *env,
                              u32 func_id, u16 offset, unsigned long *addr)
 {
         struct bpf_prog *prog = env->prog;
         bool seen_direct_write;
         void *xdp_kfunc;
         bool is_rdonly;
 
         if (bpf_dev_bound_kfunc_id(func_id)) {
                 xdp_kfunc = bpf_dev_bound_resolve_kfunc(prog, func_id);
                 if (xdp_kfunc) {
                         *addr = (unsigned long)xdp_kfunc;
                         return;
                 }
                 /* fallback to default kfunc when not supported by netdev */
         }
 
         if (offset)
                 return;
 
         if (func_id == special_kfunc_list[KF_bpf_dynptr_from_skb]) {
                 seen_direct_write = env->seen_direct_write;
                 is_rdonly = !may_access_direct_pkt_data(env, NULL, BPF_WRITE);
 
                 if (is_rdonly)
                         *addr = (unsigned long)bpf_dynptr_from_skb_rdonly;
 
                 /* restore env->seen_direct_write to its original value, since
                  * may_access_direct_pkt_data mutates it
                  */
                 env->seen_direct_write = seen_direct_write;
         }
 }
 
 static void __fixup_collection_insert_kfunc(struct bpf_insn_aux_data *insn_aux,
                                             u16 struct_meta_reg,
                                             u16 node_offset_reg,
                                             struct bpf_insn *insn,
                                             struct bpf_insn *insn_buf,
                                             int *cnt)
 {
         struct btf_struct_meta *kptr_struct_meta = insn_aux->kptr_struct_meta;
         struct bpf_insn addr[2] = { BPF_LD_IMM64(struct_meta_reg, (long)kptr_struct_meta) };
 
         insn_buf[0] = addr[0];
         insn_buf[1] = addr[1];
         insn_buf[2] = BPF_MOV64_IMM(node_offset_reg, insn_aux->insert_off);
         insn_buf[3] = *insn;
         *cnt = 4;
 }
 
 static int fixup_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
                             struct bpf_insn *insn_buf, int insn_idx, int *cnt)
 {
         const struct bpf_kfunc_desc *desc;
 
         if (!insn->imm) {
                 verbose(env, "invalid kernel function call not eliminated in verifier pass\n");
                 return -EINVAL;
         }
 
         *cnt = 0;
 
         /* insn->imm has the btf func_id. Replace it with an offset relative to
          * __bpf_call_base, unless the JIT needs to call functions that are
          * further than 32 bits away (bpf_jit_supports_far_kfunc_call()).
          */
         desc = find_kfunc_desc(env->prog, insn->imm, insn->off);
         if (!desc) {
                 verbose(env, "verifier internal error: kernel function descriptor not found for func_id %u\n",
                         insn->imm);
                 return -EFAULT;
         }
 
         if (!bpf_jit_supports_far_kfunc_call())
                 insn->imm = BPF_CALL_IMM(desc->addr);
         if (insn->off)
                 return 0;
         if (desc->func_id == special_kfunc_list[KF_bpf_obj_new_impl] ||
             desc->func_id == special_kfunc_list[KF_bpf_percpu_obj_new_impl]) {
                 struct btf_struct_meta *kptr_struct_meta = env->insn_aux_data[insn_idx].kptr_struct_meta;
                 struct bpf_insn addr[2] = { BPF_LD_IMM64(BPF_REG_2, (long)kptr_struct_meta) };
                 u64 obj_new_size = env->insn_aux_data[insn_idx].obj_new_size;
 
                 if (desc->func_id == special_kfunc_list[KF_bpf_percpu_obj_new_impl] && kptr_struct_meta) {
                         verbose(env, "verifier internal error: NULL kptr_struct_meta expected at insn_idx %d\n",
                                 insn_idx);
                         return -EFAULT;
                 }
 
                 insn_buf[0] = BPF_MOV64_IMM(BPF_REG_1, obj_new_size);
                 insn_buf[1] = addr[0];
                 insn_buf[2] = addr[1];
                 insn_buf[3] = *insn;
                 *cnt = 4;
         } else if (desc->func_id == special_kfunc_list[KF_bpf_obj_drop_impl] ||
                    desc->func_id == special_kfunc_list[KF_bpf_percpu_obj_drop_impl] ||
                    desc->func_id == special_kfunc_list[KF_bpf_refcount_acquire_impl]) {
                 struct btf_struct_meta *kptr_struct_meta = env->insn_aux_data[insn_idx].kptr_struct_meta;
                 struct bpf_insn addr[2] = { BPF_LD_IMM64(BPF_REG_2, (long)kptr_struct_meta) };
 
                 if (desc->func_id == special_kfunc_list[KF_bpf_percpu_obj_drop_impl] && kptr_struct_meta) {
                         verbose(env, "verifier internal error: NULL kptr_struct_meta expected at insn_idx %d\n",
                                 insn_idx);
                         return -EFAULT;
                 }
 
                 if (desc->func_id == special_kfunc_list[KF_bpf_refcount_acquire_impl] &&
                     !kptr_struct_meta) {
                         verbose(env, "verifier internal error: kptr_struct_meta expected at insn_idx %d\n",
                                 insn_idx);
                         return -EFAULT;
                 }
 
                 insn_buf[0] = addr[0];
                 insn_buf[1] = addr[1];
                 insn_buf[2] = *insn;
                 *cnt = 3;
         } else if (desc->func_id == special_kfunc_list[KF_bpf_list_push_back_impl] ||
                    desc->func_id == special_kfunc_list[KF_bpf_list_push_front_impl] ||
                    desc->func_id == special_kfunc_list[KF_bpf_rbtree_add_impl]) {
                 struct btf_struct_meta *kptr_struct_meta = env->insn_aux_data[insn_idx].kptr_struct_meta;
                 int struct_meta_reg = BPF_REG_3;
                 int node_offset_reg = BPF_REG_4;
 
                 /* rbtree_add has extra 'less' arg, so args-to-fixup are in diff regs */
                 if (desc->func_id == special_kfunc_list[KF_bpf_rbtree_add_impl]) {
                         struct_meta_reg = BPF_REG_4;
                         node_offset_reg = BPF_REG_5;
                 }
 
                 if (!kptr_struct_meta) {
                         verbose(env, "verifier internal error: kptr_struct_meta expected at insn_idx %d\n",
                                 insn_idx);
                         return -EFAULT;
                 }
 
                 __fixup_collection_insert_kfunc(&env->insn_aux_data[insn_idx], struct_meta_reg,
                                                 node_offset_reg, insn, insn_buf, cnt);
         } else if (desc->func_id == special_kfunc_list[KF_bpf_cast_to_kern_ctx] ||
                    desc->func_id == special_kfunc_list[KF_bpf_rdonly_cast]) {
                 insn_buf[0] = BPF_MOV64_REG(BPF_REG_0, BPF_REG_1);
                 *cnt = 1;
         } else if (is_bpf_wq_set_callback_impl_kfunc(desc->func_id)) {
                 struct bpf_insn ld_addrs[2] = { BPF_LD_IMM64(BPF_REG_4, (long)env->prog->aux) };
 
                 insn_buf[0] = ld_addrs[0];
                 insn_buf[1] = ld_addrs[1];
                 insn_buf[2] = *insn;
                 *cnt = 3;
         }
         return 0;
 }
 
 /* The function requires that first instruction in 'patch' is insnsi[prog->len - 1] */
 static int add_hidden_subprog(struct bpf_verifier_env *env, struct bpf_insn *patch, int len)
 {
         struct bpf_subprog_info *info = env->subprog_info;
         int cnt = env->subprog_cnt;
         struct bpf_prog *prog;
 
         /* We only reserve one slot for hidden subprogs in subprog_info. */
         if (env->hidden_subprog_cnt) {
                 verbose(env, "verifier internal error: only one hidden subprog supported\n");
                 return -EFAULT;
         }
         /* We're not patching any existing instruction, just appending the new
          * ones for the hidden subprog. Hence all of the adjustment operations
          * in bpf_patch_insn_data are no-ops.
          */
         prog = bpf_patch_insn_data(env, env->prog->len - 1, patch, len);
         if (!prog)
                 return -ENOMEM;
         env->prog = prog;
         info[cnt + 1].start = info[cnt].start;
         info[cnt].start = prog->len - len + 1;
         env->subprog_cnt++;
         env->hidden_subprog_cnt++;
         return 0;
 }
 
 /* Do various post-verification rewrites in a single program pass.
  * These rewrites simplify JIT and interpreter implementations.
  */
 static int do_misc_fixups(struct bpf_verifier_env *env)
 {
         struct bpf_prog *prog = env->prog;
         enum bpf_attach_type eatype = prog->expected_attach_type;
         enum bpf_prog_type prog_type = resolve_prog_type(prog);
         struct bpf_insn *insn = prog->insnsi;
         const struct bpf_func_proto *fn;
         const int insn_cnt = prog->len;
         const struct bpf_map_ops *ops;
         struct bpf_insn_aux_data *aux;
         struct bpf_insn insn_buf[16];
         struct bpf_prog *new_prog;
         struct bpf_map *map_ptr;
         int i, ret, cnt, delta = 0, cur_subprog = 0;
         struct bpf_subprog_info *subprogs = env->subprog_info;
         u16 stack_depth = subprogs[cur_subprog].stack_depth;
         u16 stack_depth_extra = 0;
 
         if (env->seen_exception && !env->exception_callback_subprog) {
                 struct bpf_insn patch[] = {
                         env->prog->insnsi[insn_cnt - 1],
                         BPF_MOV64_REG(BPF_REG_0, BPF_REG_1),
                         BPF_EXIT_INSN(),
                 };
 
                 ret = add_hidden_subprog(env, patch, ARRAY_SIZE(patch));
                 if (ret < 0)
                         return ret;
                 prog = env->prog;
                 insn = prog->insnsi;
 
                 env->exception_callback_subprog = env->subprog_cnt - 1;
                 /* Don't update insn_cnt, as add_hidden_subprog always appends insns */
                 mark_subprog_exc_cb(env, env->exception_callback_subprog);
         }
 
         for (i = 0; i < insn_cnt;) {
                 if (insn->code == (BPF_ALU64 | BPF_MOV | BPF_X) && insn->imm) {
                         if ((insn->off == BPF_ADDR_SPACE_CAST && insn->imm == 1) ||
                             (((struct bpf_map *)env->prog->aux->arena)->map_flags & BPF_F_NO_USER_CONV)) {
                                 /* convert to 32-bit mov that clears upper 32-bit */
                                 insn->code = BPF_ALU | BPF_MOV | BPF_X;
                                 /* clear off and imm, so it's a normal 'wX = wY' from JIT pov */
                                 insn->off = 0;
                                 insn->imm = 0;
                         } /* cast from as(0) to as(1) should be handled by JIT */
                         goto next_insn;
                 }
 
                 if (env->insn_aux_data[i + delta].needs_zext)
                         /* Convert BPF_CLASS(insn->code) == BPF_ALU64 to 32-bit ALU */
                         insn->code = BPF_ALU | BPF_OP(insn->code) | BPF_SRC(insn->code);
 
                 /* Make sdiv/smod divide-by-minus-one exceptions impossible. */
                 if ((insn->code == (BPF_ALU64 | BPF_MOD | BPF_K) ||
                      insn->code == (BPF_ALU64 | BPF_DIV | BPF_K) ||
                      insn->code == (BPF_ALU | BPF_MOD | BPF_K) ||
                      insn->code == (BPF_ALU | BPF_DIV | BPF_K)) &&
                     insn->off == 1 && insn->imm == -1) {
                         bool is64 = BPF_CLASS(insn->code) == BPF_ALU64;
                         bool isdiv = BPF_OP(insn->code) == BPF_DIV;
                         struct bpf_insn *patchlet;
                         struct bpf_insn chk_and_sdiv[] = {
                                 BPF_RAW_INSN((is64 ? BPF_ALU64 : BPF_ALU) |
                                              BPF_NEG | BPF_K, insn->dst_reg,
                                              0, 0, 0),
                         };
                         struct bpf_insn chk_and_smod[] = {
                                 BPF_MOV32_IMM(insn->dst_reg, 0),
                         };
 
                         patchlet = isdiv ? chk_and_sdiv : chk_and_smod;
                         cnt = isdiv ? ARRAY_SIZE(chk_and_sdiv) : ARRAY_SIZE(chk_and_smod);
 
                         new_prog = bpf_patch_insn_data(env, i + delta, patchlet, cnt);
                         if (!new_prog)
                                 return -ENOMEM;
 
                         delta    += cnt - 1;
                         env->prog = prog = new_prog;
                         insn      = new_prog->insnsi + i + delta;
                         goto next_insn;
                 }
 
                 /* Make divide-by-zero and divide-by-minus-one exceptions impossible. */
                 if (insn->code == (BPF_ALU64 | BPF_MOD | BPF_X) ||
                     insn->code == (BPF_ALU64 | BPF_DIV | BPF_X) ||
                     insn->code == (BPF_ALU | BPF_MOD | BPF_X) ||
                     insn->code == (BPF_ALU | BPF_DIV | BPF_X)) {
                         bool is64 = BPF_CLASS(insn->code) == BPF_ALU64;
                         bool isdiv = BPF_OP(insn->code) == BPF_DIV;
                         bool is_sdiv = isdiv && insn->off == 1;
                         bool is_smod = !isdiv && insn->off == 1;
                         struct bpf_insn *patchlet;
                         struct bpf_insn chk_and_div[] = {
                                 /* [R,W]x div 0 -> 0 */
                                 BPF_RAW_INSN((is64 ? BPF_JMP : BPF_JMP32) |
                                              BPF_JNE | BPF_K, insn->src_reg,
                                              0, 2, 0),
                                 BPF_ALU32_REG(BPF_XOR, insn->dst_reg, insn->dst_reg),
                                 BPF_JMP_IMM(BPF_JA, 0, 0, 1),
                                 *insn,
                         };
                         struct bpf_insn chk_and_mod[] = {
                                 /* [R,W]x mod 0 -> [R,W]x */
                                 BPF_RAW_INSN((is64 ? BPF_JMP : BPF_JMP32) |
                                              BPF_JEQ | BPF_K, insn->src_reg,
                                              0, 1 + (is64 ? 0 : 1), 0),
                                 *insn,
                                 BPF_JMP_IMM(BPF_JA, 0, 0, 1),
                                 BPF_MOV32_REG(insn->dst_reg, insn->dst_reg),
                         };
                         struct bpf_insn chk_and_sdiv[] = {
                                 /* [R,W]x sdiv 0 -> 0
                                  * LLONG_MIN sdiv -1 -> LLONG_MIN
                                  * INT_MIN sdiv -1 -> INT_MIN
                                  */
                                 BPF_MOV64_REG(BPF_REG_AX, insn->src_reg),
                                 BPF_RAW_INSN((is64 ? BPF_ALU64 : BPF_ALU) |
                                              BPF_ADD | BPF_K, BPF_REG_AX,
                                              0, 0, 1),
                                 BPF_RAW_INSN((is64 ? BPF_JMP : BPF_JMP32) |
                                              BPF_JGT | BPF_K, BPF_REG_AX,
                                              0, 4, 1),
                                 BPF_RAW_INSN((is64 ? BPF_JMP : BPF_JMP32) |
                                              BPF_JEQ | BPF_K, BPF_REG_AX,
                                              0, 1, 0),
                                 BPF_RAW_INSN((is64 ? BPF_ALU64 : BPF_ALU) |
                                              BPF_MOV | BPF_K, insn->dst_reg,
                                              0, 0, 0),
                                 /* BPF_NEG(LLONG_MIN) == -LLONG_MIN == LLONG_MIN */
                                 BPF_RAW_INSN((is64 ? BPF_ALU64 : BPF_ALU) |
                                              BPF_NEG | BPF_K, insn->dst_reg,
                                              0, 0, 0),
                                 BPF_JMP_IMM(BPF_JA, 0, 0, 1),
                                 *insn,
                         };
                         struct bpf_insn chk_and_smod[] = {
                                 /* [R,W]x mod 0 -> [R,W]x */
                                 /* [R,W]x mod -1 -> 0 */
                                 BPF_MOV64_REG(BPF_REG_AX, insn->src_reg),
                                 BPF_RAW_INSN((is64 ? BPF_ALU64 : BPF_ALU) |
                                              BPF_ADD | BPF_K, BPF_REG_AX,
                                              0, 0, 1),
                                 BPF_RAW_INSN((is64 ? BPF_JMP : BPF_JMP32) |
                                              BPF_JGT | BPF_K, BPF_REG_AX,
                                              0, 3, 1),
                                 BPF_RAW_INSN((is64 ? BPF_JMP : BPF_JMP32) |
                                              BPF_JEQ | BPF_K, BPF_REG_AX,
                                              0, 3 + (is64 ? 0 : 1), 1),
                                 BPF_MOV32_IMM(insn->dst_reg, 0),
                                 BPF_JMP_IMM(BPF_JA, 0, 0, 1),
                                 *insn,
                                 BPF_JMP_IMM(BPF_JA, 0, 0, 1),
                                 BPF_MOV32_REG(insn->dst_reg, insn->dst_reg),
                         };
 
                         if (is_sdiv) {
                                 patchlet = chk_and_sdiv;
                                 cnt = ARRAY_SIZE(chk_and_sdiv);
                         } else if (is_smod) {
                                 patchlet = chk_and_smod;
                                 cnt = ARRAY_SIZE(chk_and_smod) - (is64 ? 2 : 0);
                         } else {
                                 patchlet = isdiv ? chk_and_div : chk_and_mod;
                                 cnt = isdiv ? ARRAY_SIZE(chk_and_div) :
                                               ARRAY_SIZE(chk_and_mod) - (is64 ? 2 : 0);
                         }
 
                         new_prog = bpf_patch_insn_data(env, i + delta, patchlet, cnt);
                         if (!new_prog)
                                 return -ENOMEM;
 
                         delta    += cnt - 1;
                         env->prog = prog = new_prog;
                         insn      = new_prog->insnsi + i + delta;
                         goto next_insn;
                 }
 
                 /* Make it impossible to de-reference a userspace address */
                 if (BPF_CLASS(insn->code) == BPF_LDX &&
                     (BPF_MODE(insn->code) == BPF_PROBE_MEM ||
                      BPF_MODE(insn->code) == BPF_PROBE_MEMSX)) {
                         struct bpf_insn *patch = &insn_buf[0];
                         u64 uaddress_limit = bpf_arch_uaddress_limit();
 
                         if (!uaddress_limit)
                                 goto next_insn;
 
                         *patch++ = BPF_MOV64_REG(BPF_REG_AX, insn->src_reg);
                         if (insn->off)
                                 *patch++ = BPF_ALU64_IMM(BPF_ADD, BPF_REG_AX, insn->off);
                         *patch++ = BPF_ALU64_IMM(BPF_RSH, BPF_REG_AX, 32);
                         *patch++ = BPF_JMP_IMM(BPF_JLE, BPF_REG_AX, uaddress_limit >> 32, 2);
                         *patch++ = *insn;
                         *patch++ = BPF_JMP_IMM(BPF_JA, 0, 0, 1);
                         *patch++ = BPF_MOV64_IMM(insn->dst_reg, 0);
 
                         cnt = patch - insn_buf;
                         new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
                         if (!new_prog)
                                 return -ENOMEM;
 
                         delta    += cnt - 1;
                         env->prog = prog = new_prog;
                         insn      = new_prog->insnsi + i + delta;
                         goto next_insn;
                 }
 
                 /* Implement LD_ABS and LD_IND with a rewrite, if supported by the program type. */
                 if (BPF_CLASS(insn->code) == BPF_LD &&
                     (BPF_MODE(insn->code) == BPF_ABS ||
                      BPF_MODE(insn->code) == BPF_IND)) {
                         cnt = env->ops->gen_ld_abs(insn, insn_buf);
                         if (cnt == 0 || cnt >= ARRAY_SIZE(insn_buf)) {
                                 verbose(env, "bpf verifier is misconfigured\n");
                                 return -EINVAL;
                         }
 
                         new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
                         if (!new_prog)
                                 return -ENOMEM;
 
                         delta    += cnt - 1;
                         env->prog = prog = new_prog;
                         insn      = new_prog->insnsi + i + delta;
                         goto next_insn;
                 }
 
                 /* Rewrite pointer arithmetic to mitigate speculation attacks. */
                 if (insn->code == (BPF_ALU64 | BPF_ADD | BPF_X) ||
                     insn->code == (BPF_ALU64 | BPF_SUB | BPF_X)) {
                         const u8 code_add = BPF_ALU64 | BPF_ADD | BPF_X;
                         const u8 code_sub = BPF_ALU64 | BPF_SUB | BPF_X;
                         struct bpf_insn *patch = &insn_buf[0];
                         bool issrc, isneg, isimm;
                         u32 off_reg;
 
                         aux = &env->insn_aux_data[i + delta];
                         if (!aux->alu_state ||
                             aux->alu_state == BPF_ALU_NON_POINTER)
                                 goto next_insn;
 
                         isneg = aux->alu_state & BPF_ALU_NEG_VALUE;
                         issrc = (aux->alu_state & BPF_ALU_SANITIZE) ==
                                 BPF_ALU_SANITIZE_SRC;
                         isimm = aux->alu_state & BPF_ALU_IMMEDIATE;
 
                         off_reg = issrc ? insn->src_reg : insn->dst_reg;
                         if (isimm) {
                                 *patch++ = BPF_MOV32_IMM(BPF_REG_AX, aux->alu_limit);
                         } else {
                                 if (isneg)
                                         *patch++ = BPF_ALU64_IMM(BPF_MUL, off_reg, -1);
                                 *patch++ = BPF_MOV32_IMM(BPF_REG_AX, aux->alu_limit);
                                 *patch++ = BPF_ALU64_REG(BPF_SUB, BPF_REG_AX, off_reg);
                                 *patch++ = BPF_ALU64_REG(BPF_OR, BPF_REG_AX, off_reg);
                                 *patch++ = BPF_ALU64_IMM(BPF_NEG, BPF_REG_AX, 0);
                                 *patch++ = BPF_ALU64_IMM(BPF_ARSH, BPF_REG_AX, 63);
                                 *patch++ = BPF_ALU64_REG(BPF_AND, BPF_REG_AX, off_reg);
                         }
                         if (!issrc)
                                 *patch++ = BPF_MOV64_REG(insn->dst_reg, insn->src_reg);
                         insn->src_reg = BPF_REG_AX;
                         if (isneg)
                                 insn->code = insn->code == code_add ?
                                              code_sub : code_add;
                         *patch++ = *insn;
                         if (issrc && isneg && !isimm)
                                 *patch++ = BPF_ALU64_IMM(BPF_MUL, off_reg, -1);
                         cnt = patch - insn_buf;
 
                         new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
                         if (!new_prog)
                                 return -ENOMEM;
 
                         delta    += cnt - 1;
                         env->prog = prog = new_prog;
                         insn      = new_prog->insnsi + i + delta;
                         goto next_insn;
                 }
 
                 if (is_may_goto_insn(insn)) {
                         int stack_off = -stack_depth - 8;
 
                         stack_depth_extra = 8;
                         insn_buf[0] = BPF_LDX_MEM(BPF_DW, BPF_REG_AX, BPF_REG_10, stack_off);
                         if (insn->off >= 0)
                                 insn_buf[1] = BPF_JMP_IMM(BPF_JEQ, BPF_REG_AX, 0, insn->off + 2);
                         else
                                 insn_buf[1] = BPF_JMP_IMM(BPF_JEQ, BPF_REG_AX, 0, insn->off - 1);
                         insn_buf[2] = BPF_ALU64_IMM(BPF_SUB, BPF_REG_AX, 1);
                         insn_buf[3] = BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_AX, stack_off);
                         cnt = 4;
 
                         new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
                         if (!new_prog)
                                 return -ENOMEM;
 
                         delta += cnt - 1;
                         env->prog = prog = new_prog;
                         insn = new_prog->insnsi + i + delta;
                         goto next_insn;
                 }
 
                 if (insn->code != (BPF_JMP | BPF_CALL))
                         goto next_insn;
                 if (insn->src_reg == BPF_PSEUDO_CALL)
                         goto next_insn;
                 if (insn->src_reg == BPF_PSEUDO_KFUNC_CALL) {
                         ret = fixup_kfunc_call(env, insn, insn_buf, i + delta, &cnt);
                         if (ret)
                                 return ret;
                         if (cnt == 0)
                                 goto next_insn;
 
                         new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
                         if (!new_prog)
                                 return -ENOMEM;
 
                         delta    += cnt - 1;
                         env->prog = prog = new_prog;
                         insn      = new_prog->insnsi + i + delta;
                         goto next_insn;
                 }
 
                 /* Skip inlining the helper call if the JIT does it. */
                 if (bpf_jit_inlines_helper_call(insn->imm))
                         goto next_insn;
 
                 if (insn->imm == BPF_FUNC_get_route_realm)
                         prog->dst_needed = 1;
                 if (insn->imm == BPF_FUNC_get_prandom_u32)
                         bpf_user_rnd_init_once();
                 if (insn->imm == BPF_FUNC_override_return)
                         prog->kprobe_override = 1;
                 if (insn->imm == BPF_FUNC_tail_call) {
                         /* If we tail call into other programs, we
                          * cannot make any assumptions since they can
                          * be replaced dynamically during runtime in
                          * the program array.
                          */
                         prog->cb_access = 1;
                         if (!allow_tail_call_in_subprogs(env))
                                 prog->aux->stack_depth = MAX_BPF_STACK;
                         prog->aux->max_pkt_offset = MAX_PACKET_OFF;
 
                         /* mark bpf_tail_call as different opcode to avoid
                          * conditional branch in the interpreter for every normal
                          * call and to prevent accidental JITing by JIT compiler
                          * that doesn't support bpf_tail_call yet
                          */
                         insn->imm = 0;
                         insn->code = BPF_JMP | BPF_TAIL_CALL;
 
                         aux = &env->insn_aux_data[i + delta];
                         if (env->bpf_capable && !prog->blinding_requested &&
                             prog->jit_requested &&
                             !bpf_map_key_poisoned(aux) &&
                             !bpf_map_ptr_poisoned(aux) &&
                             !bpf_map_ptr_unpriv(aux)) {
                                 struct bpf_jit_poke_descriptor desc = {
                                         .reason = BPF_POKE_REASON_TAIL_CALL,
                                         .tail_call.map = aux->map_ptr_state.map_ptr,
                                         .tail_call.key = bpf_map_key_immediate(aux),
                                         .insn_idx = i + delta,
                                 };
 
                                 ret = bpf_jit_add_poke_descriptor(prog, &desc);
                                 if (ret < 0) {
                                         verbose(env, "adding tail call poke descriptor failed\n");
                                         return ret;
                                 }
 
                                 insn->imm = ret + 1;
                                 goto next_insn;
                         }
 
                         if (!bpf_map_ptr_unpriv(aux))
                                 goto next_insn;
 
                         /* instead of changing every JIT dealing with tail_call
                          * emit two extra insns:
                          * if (index >= max_entries) goto out;
                          * index &= array->index_mask;
                          * to avoid out-of-bounds cpu speculation
                          */
                         if (bpf_map_ptr_poisoned(aux)) {
                                 verbose(env, "tail_call abusing map_ptr\n");
                                 return -EINVAL;
                         }
 
                         map_ptr = aux->map_ptr_state.map_ptr;
                         insn_buf[0] = BPF_JMP_IMM(BPF_JGE, BPF_REG_3,
                                                   map_ptr->max_entries, 2);
                         insn_buf[1] = BPF_ALU32_IMM(BPF_AND, BPF_REG_3,
                                                     container_of(map_ptr,
                                                                  struct bpf_array,
                                                                  map)->index_mask);
                         insn_buf[2] = *insn;
                         cnt = 3;
                         new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
                         if (!new_prog)
                                 return -ENOMEM;
 
                         delta    += cnt - 1;
                         env->prog = prog = new_prog;
                         insn      = new_prog->insnsi + i + delta;
                         goto next_insn;
                 }
 
                 if (insn->imm == BPF_FUNC_timer_set_callback) {
                         /* The verifier will process callback_fn as many times as necessary
                          * with different maps and the register states prepared by
                          * set_timer_callback_state will be accurate.
                          *
                          * The following use case is valid:
                          *   map1 is shared by prog1, prog2, prog3.
                          *   prog1 calls bpf_timer_init for some map1 elements
                          *   prog2 calls bpf_timer_set_callback for some map1 elements.
                          *     Those that were not bpf_timer_init-ed will return -EINVAL.
                          *   prog3 calls bpf_timer_start for some map1 elements.
                          *     Those that were not both bpf_timer_init-ed and
                          *     bpf_timer_set_callback-ed will return -EINVAL.
                          */
                         struct bpf_insn ld_addrs[2] = {
                                 BPF_LD_IMM64(BPF_REG_3, (long)prog->aux),
                         };
 
                         insn_buf[0] = ld_addrs[0];
                         insn_buf[1] = ld_addrs[1];
                         insn_buf[2] = *insn;
                         cnt = 3;
 
                         new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
                         if (!new_prog)
                                 return -ENOMEM;
 
                         delta    += cnt - 1;
                         env->prog = prog = new_prog;
                         insn      = new_prog->insnsi + i + delta;
                         goto patch_call_imm;
                 }
 
                 if (is_storage_get_function(insn->imm)) {
                         if (!in_sleepable(env) ||
                             env->insn_aux_data[i + delta].storage_get_func_atomic)
                                 insn_buf[0] = BPF_MOV64_IMM(BPF_REG_5, (__force __s32)GFP_ATOMIC);
                         else
                                 insn_buf[0] = BPF_MOV64_IMM(BPF_REG_5, (__force __s32)GFP_KERNEL);
                         insn_buf[1] = *insn;
                         cnt = 2;
 
                         new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
                         if (!new_prog)
                                 return -ENOMEM;
 
                         delta += cnt - 1;
                         env->prog = prog = new_prog;
                         insn = new_prog->insnsi + i + delta;
                         goto patch_call_imm;
                 }
 
                 /* bpf_per_cpu_ptr() and bpf_this_cpu_ptr() */
                 if (env->insn_aux_data[i + delta].call_with_percpu_alloc_ptr) {
                         /* patch with 'r1 = *(u64 *)(r1 + 0)' since for percpu data,
                          * bpf_mem_alloc() returns a ptr to the percpu data ptr.
                          */
                         insn_buf[0] = BPF_LDX_MEM(BPF_DW, BPF_REG_1, BPF_REG_1, 0);
                         insn_buf[1] = *insn;
                         cnt = 2;
 
                         new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
                         if (!new_prog)
                                 return -ENOMEM;
 
                         delta += cnt - 1;
                         env->prog = prog = new_prog;
                         insn = new_prog->insnsi + i + delta;
                         goto patch_call_imm;
                 }
 
                 /* BPF_EMIT_CALL() assumptions in some of the map_gen_lookup
                  * and other inlining handlers are currently limited to 64 bit
                  * only.
                  */
                 if (prog->jit_requested && BITS_PER_LONG == 64 &&
                     (insn->imm == BPF_FUNC_map_lookup_elem ||
                      insn->imm == BPF_FUNC_map_update_elem ||
                      insn->imm == BPF_FUNC_map_delete_elem ||
                      insn->imm == BPF_FUNC_map_push_elem   ||
                      insn->imm == BPF_FUNC_map_pop_elem    ||
                      insn->imm == BPF_FUNC_map_peek_elem   ||
                      insn->imm == BPF_FUNC_redirect_map    ||
                      insn->imm == BPF_FUNC_for_each_map_elem ||
                      insn->imm == BPF_FUNC_map_lookup_percpu_elem)) {
                         aux = &env->insn_aux_data[i + delta];
                         if (bpf_map_ptr_poisoned(aux))
                                 goto patch_call_imm;
 
                         map_ptr = aux->map_ptr_state.map_ptr;
                         ops = map_ptr->ops;
                         if (insn->imm == BPF_FUNC_map_lookup_elem &&
                             ops->map_gen_lookup) {
                                 cnt = ops->map_gen_lookup(map_ptr, insn_buf);
                                 if (cnt == -EOPNOTSUPP)
                                         goto patch_map_ops_generic;
                                 if (cnt <= 0 || cnt >= ARRAY_SIZE(insn_buf)) {
                                         verbose(env, "bpf verifier is misconfigured\n");
                                         return -EINVAL;
                                 }
 
                                 new_prog = bpf_patch_insn_data(env, i + delta,
                                                                insn_buf, cnt);
                                 if (!new_prog)
                                         return -ENOMEM;
 
                                 delta    += cnt - 1;
                                 env->prog = prog = new_prog;
                                 insn      = new_prog->insnsi + i + delta;
                                 goto next_insn;
                         }
 
                         BUILD_BUG_ON(!__same_type(ops->map_lookup_elem,
                                      (void *(*)(struct bpf_map *map, void *key))NULL));
                         BUILD_BUG_ON(!__same_type(ops->map_delete_elem,
                                      (long (*)(struct bpf_map *map, void *key))NULL));
                         BUILD_BUG_ON(!__same_type(ops->map_update_elem,
                                      (long (*)(struct bpf_map *map, void *key, void *value,
                                               u64 flags))NULL));
                         BUILD_BUG_ON(!__same_type(ops->map_push_elem,
                                      (long (*)(struct bpf_map *map, void *value,
                                               u64 flags))NULL));
                         BUILD_BUG_ON(!__same_type(ops->map_pop_elem,
                                      (long (*)(struct bpf_map *map, void *value))NULL));
                         BUILD_BUG_ON(!__same_type(ops->map_peek_elem,
                                      (long (*)(struct bpf_map *map, void *value))NULL));
                         BUILD_BUG_ON(!__same_type(ops->map_redirect,
                                      (long (*)(struct bpf_map *map, u64 index, u64 flags))NULL));
                         BUILD_BUG_ON(!__same_type(ops->map_for_each_callback,
                                      (long (*)(struct bpf_map *map,
                                               bpf_callback_t callback_fn,
                                               void *callback_ctx,
                                               u64 flags))NULL));
                         BUILD_BUG_ON(!__same_type(ops->map_lookup_percpu_elem,
                                      (void *(*)(struct bpf_map *map, void *key, u32 cpu))NULL));
 
 patch_map_ops_generic:
                         switch (insn->imm) {
                         case BPF_FUNC_map_lookup_elem:
                                 insn->imm = BPF_CALL_IMM(ops->map_lookup_elem);
                                 goto next_insn;
                         case BPF_FUNC_map_update_elem:
                                 insn->imm = BPF_CALL_IMM(ops->map_update_elem);
                                 goto next_insn;
                         case BPF_FUNC_map_delete_elem:
                                 insn->imm = BPF_CALL_IMM(ops->map_delete_elem);
                                 goto next_insn;
                         case BPF_FUNC_map_push_elem:
                                 insn->imm = BPF_CALL_IMM(ops->map_push_elem);
                                 goto next_insn;
                         case BPF_FUNC_map_pop_elem:
                                 insn->imm = BPF_CALL_IMM(ops->map_pop_elem);
                                 goto next_insn;
                         case BPF_FUNC_map_peek_elem:
                                 insn->imm = BPF_CALL_IMM(ops->map_peek_elem);
                                 goto next_insn;
                         case BPF_FUNC_redirect_map:
                                 insn->imm = BPF_CALL_IMM(ops->map_redirect);
                                 goto next_insn;
                         case BPF_FUNC_for_each_map_elem:
                                 insn->imm = BPF_CALL_IMM(ops->map_for_each_callback);
                                 goto next_insn;
                         case BPF_FUNC_map_lookup_percpu_elem:
                                 insn->imm = BPF_CALL_IMM(ops->map_lookup_percpu_elem);
                                 goto next_insn;
                         }
 
                         goto patch_call_imm;
                 }
 
                 /* Implement bpf_jiffies64 inline. */
                 if (prog->jit_requested && BITS_PER_LONG == 64 &&
                     insn->imm == BPF_FUNC_jiffies64) {
                         struct bpf_insn ld_jiffies_addr[2] = {
                                 BPF_LD_IMM64(BPF_REG_0,
                                              (unsigned long)&jiffies),
                         };
 
                         insn_buf[0] = ld_jiffies_addr[0];
                         insn_buf[1] = ld_jiffies_addr[1];
                         insn_buf[2] = BPF_LDX_MEM(BPF_DW, BPF_REG_0,
                                                   BPF_REG_0, 0);
                         cnt = 3;
 
                         new_prog = bpf_patch_insn_data(env, i + delta, insn_buf,
                                                        cnt);
                         if (!new_prog)
                                 return -ENOMEM;
 
                         delta    += cnt - 1;
                         env->prog = prog = new_prog;
                         insn      = new_prog->insnsi + i + delta;
                         goto next_insn;
                 }
 
 #if defined(CONFIG_X86_64) && !defined(CONFIG_UML)
                 /* Implement bpf_get_smp_processor_id() inline. */
                 if (insn->imm == BPF_FUNC_get_smp_processor_id &&
                     prog->jit_requested && bpf_jit_supports_percpu_insn()) {
                         /* BPF_FUNC_get_smp_processor_id inlining is an
                          * optimization, so if pcpu_hot.cpu_number is ever
                          * changed in some incompatible and hard to support
                          * way, it's fine to back out this inlining logic
                          */
                         insn_buf[0] = BPF_MOV32_IMM(BPF_REG_0, (u32)(unsigned long)&pcpu_hot.cpu_number);
                         insn_buf[1] = BPF_MOV64_PERCPU_REG(BPF_REG_0, BPF_REG_0);
                         insn_buf[2] = BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_0, 0);
                         cnt = 3;
 
                         new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
                         if (!new_prog)
                                 return -ENOMEM;
 
                         delta    += cnt - 1;
                         env->prog = prog = new_prog;
                         insn      = new_prog->insnsi + i + delta;
                         goto next_insn;
                 }
 #endif
                 /* Implement bpf_get_func_arg inline. */
                 if (prog_type == BPF_PROG_TYPE_TRACING &&
                     insn->imm == BPF_FUNC_get_func_arg) {
                         /* Load nr_args from ctx - 8 */
                         insn_buf[0] = BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_1, -8);
                         insn_buf[1] = BPF_JMP32_REG(BPF_JGE, BPF_REG_2, BPF_REG_0, 6);
                         insn_buf[2] = BPF_ALU64_IMM(BPF_LSH, BPF_REG_2, 3);
                         insn_buf[3] = BPF_ALU64_REG(BPF_ADD, BPF_REG_2, BPF_REG_1);
                         insn_buf[4] = BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_2, 0);
                         insn_buf[5] = BPF_STX_MEM(BPF_DW, BPF_REG_3, BPF_REG_0, 0);
                         insn_buf[6] = BPF_MOV64_IMM(BPF_REG_0, 0);
                         insn_buf[7] = BPF_JMP_A(1);
                         insn_buf[8] = BPF_MOV64_IMM(BPF_REG_0, -EINVAL);
                         cnt = 9;
 
                         new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
                         if (!new_prog)
                                 return -ENOMEM;
 
                         delta    += cnt - 1;
                         env->prog = prog = new_prog;
                         insn      = new_prog->insnsi + i + delta;
                         goto next_insn;
                 }
 
                 /* Implement bpf_get_func_ret inline. */
                 if (prog_type == BPF_PROG_TYPE_TRACING &&
                     insn->imm == BPF_FUNC_get_func_ret) {
                         if (eatype == BPF_TRACE_FEXIT ||
                             eatype == BPF_MODIFY_RETURN) {
                                 /* Load nr_args from ctx - 8 */
                                 insn_buf[0] = BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_1, -8);
                                 insn_buf[1] = BPF_ALU64_IMM(BPF_LSH, BPF_REG_0, 3);
                                 insn_buf[2] = BPF_ALU64_REG(BPF_ADD, BPF_REG_0, BPF_REG_1);
                                 insn_buf[3] = BPF_LDX_MEM(BPF_DW, BPF_REG_3, BPF_REG_0, 0);
                                 insn_buf[4] = BPF_STX_MEM(BPF_DW, BPF_REG_2, BPF_REG_3, 0);
                                 insn_buf[5] = BPF_MOV64_IMM(BPF_REG_0, 0);
                                 cnt = 6;
                         } else {
                                 insn_buf[0] = BPF_MOV64_IMM(BPF_REG_0, -EOPNOTSUPP);
                                 cnt = 1;
                         }
 
                         new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
                         if (!new_prog)
                                 return -ENOMEM;
 
                         delta    += cnt - 1;
                         env->prog = prog = new_prog;
                         insn      = new_prog->insnsi + i + delta;
                         goto next_insn;
                 }
 
                 /* Implement get_func_arg_cnt inline. */
                 if (prog_type == BPF_PROG_TYPE_TRACING &&
                     insn->imm == BPF_FUNC_get_func_arg_cnt) {
                         /* Load nr_args from ctx - 8 */
                         insn_buf[0] = BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_1, -8);
 
                         new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, 1);
                         if (!new_prog)
                                 return -ENOMEM;
 
                         env->prog = prog = new_prog;
                         insn      = new_prog->insnsi + i + delta;
                         goto next_insn;
                 }
 
                 /* Implement bpf_get_func_ip inline. */
                 if (prog_type == BPF_PROG_TYPE_TRACING &&
                     insn->imm == BPF_FUNC_get_func_ip) {
                         /* Load IP address from ctx - 16 */
                         insn_buf[0] = BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_1, -16);
 
                         new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, 1);
                         if (!new_prog)
                                 return -ENOMEM;
 
                         env->prog = prog = new_prog;
                         insn      = new_prog->insnsi + i + delta;
                         goto next_insn;
                 }
 
                 /* Implement bpf_get_branch_snapshot inline. */
                 if (IS_ENABLED(CONFIG_PERF_EVENTS) &&
                     prog->jit_requested && BITS_PER_LONG == 64 &&
                     insn->imm == BPF_FUNC_get_branch_snapshot) {
                         /* We are dealing with the following func protos:
                          * u64 bpf_get_branch_snapshot(void *buf, u32 size, u64 flags);
                          * int perf_snapshot_branch_stack(struct perf_branch_entry *entries, u32 cnt);
                          */
                         const u32 br_entry_size = sizeof(struct perf_branch_entry);
 
                         /* struct perf_branch_entry is part of UAPI and is
                          * used as an array element, so extremely unlikely to
                          * ever grow or shrink
                          */
                         BUILD_BUG_ON(br_entry_size != 24);
 
                         /* if (unlikely(flags)) return -EINVAL */
                         insn_buf[0] = BPF_JMP_IMM(BPF_JNE, BPF_REG_3, 0, 7);
 
                         /* Transform size (bytes) into number of entries (cnt = size / 24).
                          * But to avoid expensive division instruction, we implement
                          * divide-by-3 through multiplication, followed by further
                          * division by 8 through 3-bit right shift.
                          * Refer to book "Hacker's Delight, 2nd ed." by Henry S. Warren, Jr.,
                          * p. 227, chapter "Unsigned Division by 3" for details and proofs.
                          *
                          * N / 3 <=> M * N / 2^33, where M = (2^33 + 1) / 3 = 0xaaaaaaab.
                          */
                         insn_buf[1] = BPF_MOV32_IMM(BPF_REG_0, 0xaaaaaaab);
                         insn_buf[2] = BPF_ALU64_REG(BPF_MUL, BPF_REG_2, BPF_REG_0);
                         insn_buf[3] = BPF_ALU64_IMM(BPF_RSH, BPF_REG_2, 36);
 
                         /* call perf_snapshot_branch_stack implementation */
                         insn_buf[4] = BPF_EMIT_CALL(static_call_query(perf_snapshot_branch_stack));
                         /* if (entry_cnt == 0) return -ENOENT */
                         insn_buf[5] = BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 4);
                         /* return entry_cnt * sizeof(struct perf_branch_entry) */
                         insn_buf[6] = BPF_ALU32_IMM(BPF_MUL, BPF_REG_0, br_entry_size);
                         insn_buf[7] = BPF_JMP_A(3);
                         /* return -EINVAL; */
                         insn_buf[8] = BPF_MOV64_IMM(BPF_REG_0, -EINVAL);
                         insn_buf[9] = BPF_JMP_A(1);
                         /* return -ENOENT; */
                         insn_buf[10] = BPF_MOV64_IMM(BPF_REG_0, -ENOENT);
                         cnt = 11;
 
                         new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
                         if (!new_prog)
                                 return -ENOMEM;
 
                         delta    += cnt - 1;
                         env->prog = prog = new_prog;
                         insn      = new_prog->insnsi + i + delta;
                         continue;
                 }
 
                 /* Implement bpf_kptr_xchg inline */
                 if (prog->jit_requested && BITS_PER_LONG == 64 &&
                     insn->imm == BPF_FUNC_kptr_xchg &&
                     bpf_jit_supports_ptr_xchg()) {
                         insn_buf[0] = BPF_MOV64_REG(BPF_REG_0, BPF_REG_2);
                         insn_buf[1] = BPF_ATOMIC_OP(BPF_DW, BPF_XCHG, BPF_REG_1, BPF_REG_0, 0);
                         cnt = 2;
 
                         new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
                         if (!new_prog)
                                 return -ENOMEM;
 
                         delta    += cnt - 1;
                         env->prog = prog = new_prog;
                         insn      = new_prog->insnsi + i + delta;
                         goto next_insn;
                 }
 patch_call_imm:
                 fn = env->ops->get_func_proto(insn->imm, env->prog);
                 /* all functions that have prototype and verifier allowed
                  * programs to call them, must be real in-kernel functions
                  */
                 if (!fn->func) {
                         verbose(env,
                                 "kernel subsystem misconfigured func %s#%d\n",
                                 func_id_name(insn->imm), insn->imm);
                         return -EFAULT;
                 }
                 insn->imm = fn->func - __bpf_call_base;
 next_insn:
                 if (subprogs[cur_subprog + 1].start == i + delta + 1) {
                         subprogs[cur_subprog].stack_depth += stack_depth_extra;
                         subprogs[cur_subprog].stack_extra = stack_depth_extra;
                         cur_subprog++;
                         stack_depth = subprogs[cur_subprog].stack_depth;
                         stack_depth_extra = 0;
                 }
                 i++;
                 insn++;
         }
 
         env->prog->aux->stack_depth = subprogs[0].stack_depth;
         for (i = 0; i < env->subprog_cnt; i++) {
                 int subprog_start = subprogs[i].start;
                 int stack_slots = subprogs[i].stack_extra / 8;
 
                 if (!stack_slots)
                         continue;
                 if (stack_slots > 1) {
                         verbose(env, "verifier bug: stack_slots supports may_goto only\n");
                         return -EFAULT;
                 }
 
                 /* Add ST insn to subprog prologue to init extra stack */
                 insn_buf[0] = BPF_ST_MEM(BPF_DW, BPF_REG_FP,
                                          -subprogs[i].stack_depth, BPF_MAX_LOOPS);
                 /* Copy first actual insn to preserve it */
                 insn_buf[1] = env->prog->insnsi[subprog_start];
 
                 new_prog = bpf_patch_insn_data(env, subprog_start, insn_buf, 2);
                 if (!new_prog)
                         return -ENOMEM;
                 env->prog = prog = new_prog;
                 /*
                  * If may_goto is a first insn of a prog there could be a jmp
                  * insn that points to it, hence adjust all such jmps to point
                  * to insn after BPF_ST that inits may_goto count.
                  * Adjustment will succeed because bpf_patch_insn_data() didn't fail.
                  */
                 WARN_ON(adjust_jmp_off(env->prog, subprog_start, 1));
         }
 
         /* Since poke tab is now finalized, publish aux to tracker. */
         for (i = 0; i < prog->aux->size_poke_tab; i++) {
                 map_ptr = prog->aux->poke_tab[i].tail_call.map;
                 if (!map_ptr->ops->map_poke_track ||
                     !map_ptr->ops->map_poke_untrack ||
                     !map_ptr->ops->map_poke_run) {
                         verbose(env, "bpf verifier is misconfigured\n");
                         return -EINVAL;
                 }
 
                 ret = map_ptr->ops->map_poke_track(map_ptr, prog->aux);
                 if (ret < 0) {
                         verbose(env, "tracking tail call prog failed\n");
                         return ret;
                 }
         }
 
         sort_kfunc_descs_by_imm_off(env->prog);
 
         return 0;
 }
 
 static struct bpf_prog *inline_bpf_loop(struct bpf_verifier_env *env,
                                         int position,
                                         s32 stack_base,
                                         u32 callback_subprogno,
                                         u32 *cnt)
 {
         s32 r6_offset = stack_base + 0 * BPF_REG_SIZE;
         s32 r7_offset = stack_base + 1 * BPF_REG_SIZE;
         s32 r8_offset = stack_base + 2 * BPF_REG_SIZE;
         int reg_loop_max = BPF_REG_6;
         int reg_loop_cnt = BPF_REG_7;
         int reg_loop_ctx = BPF_REG_8;
 
         struct bpf_prog *new_prog;
         u32 callback_start;
         u32 call_insn_offset;
         s32 callback_offset;
 
         /* This represents an inlined version of bpf_iter.c:bpf_loop,
          * be careful to modify this code in sync.
          */
         struct bpf_insn insn_buf[] = {
                 /* Return error and jump to the end of the patch if
                  * expected number of iterations is too big.
                  */
                 BPF_JMP_IMM(BPF_JLE, BPF_REG_1, BPF_MAX_LOOPS, 2),
                 BPF_MOV32_IMM(BPF_REG_0, -E2BIG),
                 BPF_JMP_IMM(BPF_JA, 0, 0, 16),
                 /* spill R6, R7, R8 to use these as loop vars */
                 BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_6, r6_offset),
                 BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_7, r7_offset),
                 BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_8, r8_offset),
                 /* initialize loop vars */
                 BPF_MOV64_REG(reg_loop_max, BPF_REG_1),
                 BPF_MOV32_IMM(reg_loop_cnt, 0),
                 BPF_MOV64_REG(reg_loop_ctx, BPF_REG_3),
                 /* loop header,
                  * if reg_loop_cnt >= reg_loop_max skip the loop body
                  */
                 BPF_JMP_REG(BPF_JGE, reg_loop_cnt, reg_loop_max, 5),
                 /* callback call,
                  * correct callback offset would be set after patching
                  */
                 BPF_MOV64_REG(BPF_REG_1, reg_loop_cnt),
                 BPF_MOV64_REG(BPF_REG_2, reg_loop_ctx),
                 BPF_CALL_REL(0),
                 /* increment loop counter */
                 BPF_ALU64_IMM(BPF_ADD, reg_loop_cnt, 1),
                 /* jump to loop header if callback returned 0 */
                 BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, -6),
                 /* return value of bpf_loop,
                  * set R0 to the number of iterations
                  */
                 BPF_MOV64_REG(BPF_REG_0, reg_loop_cnt),
                 /* restore original values of R6, R7, R8 */
                 BPF_LDX_MEM(BPF_DW, BPF_REG_6, BPF_REG_10, r6_offset),
                 BPF_LDX_MEM(BPF_DW, BPF_REG_7, BPF_REG_10, r7_offset),
                 BPF_LDX_MEM(BPF_DW, BPF_REG_8, BPF_REG_10, r8_offset),
         };
 
         *cnt = ARRAY_SIZE(insn_buf);
         new_prog = bpf_patch_insn_data(env, position, insn_buf, *cnt);
         if (!new_prog)
                 return new_prog;
 
         /* callback start is known only after patching */
         callback_start = env->subprog_info[callback_subprogno].start;
         /* Note: insn_buf[12] is an offset of BPF_CALL_REL instruction */
         call_insn_offset = position + 12;
         callback_offset = callback_start - call_insn_offset - 1;
         new_prog->insnsi[call_insn_offset].imm = callback_offset;
 
         return new_prog;
 }
 
 static bool is_bpf_loop_call(struct bpf_insn *insn)
 {
         return insn->code == (BPF_JMP | BPF_CALL) &&
                 insn->src_reg == 0 &&
                 insn->imm == BPF_FUNC_loop;
 }
 
 /* For all sub-programs in the program (including main) check
  * insn_aux_data to see if there are bpf_loop calls that require
  * inlining. If such calls are found the calls are replaced with a
  * sequence of instructions produced by `inline_bpf_loop` function and
  * subprog stack_depth is increased by the size of 3 registers.
  * This stack space is used to spill values of the R6, R7, R8.  These
  * registers are used to store the loop bound, counter and context
  * variables.
  */
 static int optimize_bpf_loop(struct bpf_verifier_env *env)
 {
         struct bpf_subprog_info *subprogs = env->subprog_info;
         int i, cur_subprog = 0, cnt, delta = 0;
         struct bpf_insn *insn = env->prog->insnsi;
         int insn_cnt = env->prog->len;
         u16 stack_depth = subprogs[cur_subprog].stack_depth;
         u16 stack_depth_roundup = round_up(stack_depth, 8) - stack_depth;
         u16 stack_depth_extra = 0;
 
         for (i = 0; i < insn_cnt; i++, insn++) {
                 struct bpf_loop_inline_state *inline_state =
                         &env->insn_aux_data[i + delta].loop_inline_state;
 
                 if (is_bpf_loop_call(insn) && inline_state->fit_for_inline) {
                         struct bpf_prog *new_prog;
 
                         stack_depth_extra = BPF_REG_SIZE * 3 + stack_depth_roundup;
                         new_prog = inline_bpf_loop(env,
                                                    i + delta,
                                                    -(stack_depth + stack_depth_extra),
                                                    inline_state->callback_subprogno,
                                                    &cnt);
                         if (!new_prog)
                                 return -ENOMEM;
 
                         delta     += cnt - 1;
                         env->prog  = new_prog;
                         insn       = new_prog->insnsi + i + delta;
                 }
 
                 if (subprogs[cur_subprog + 1].start == i + delta + 1) {
                         subprogs[cur_subprog].stack_depth += stack_depth_extra;
                         cur_subprog++;
                         stack_depth = subprogs[cur_subprog].stack_depth;
                         stack_depth_roundup = round_up(stack_depth, 8) - stack_depth;
                         stack_depth_extra = 0;
                 }
         }
 
         env->prog->aux->stack_depth = env->subprog_info[0].stack_depth;
 
         return 0;
 }
 
 static void free_states(struct bpf_verifier_env *env)
 {
         struct bpf_verifier_state_list *sl, *sln;
         int i;
 
         sl = env->free_list;
         while (sl) {
                 sln = sl->next;
                 free_verifier_state(&sl->state, false);
                 kfree(sl);
                 sl = sln;
         }
         env->free_list = NULL;
 
         if (!env->explored_states)
                 return;
 
         for (i = 0; i < state_htab_size(env); i++) {
                 sl = env->explored_states[i];
 
                 while (sl) {
                         sln = sl->next;
                         free_verifier_state(&sl->state, false);
                         kfree(sl);
                         sl = sln;
                 }
                 env->explored_states[i] = NULL;
         }
 }
 
 static int do_check_common(struct bpf_verifier_env *env, int subprog)
 {
         bool pop_log = !(env->log.level & BPF_LOG_LEVEL2);
         struct bpf_subprog_info *sub = subprog_info(env, subprog);
         struct bpf_verifier_state *state;
         struct bpf_reg_state *regs;
         int ret, i;
 
         env->prev_linfo = NULL;
         env->pass_cnt++;
 
         state = kzalloc(sizeof(struct bpf_verifier_state), GFP_KERNEL);
         if (!state)
                 return -ENOMEM;
         state->curframe = 0;
         state->speculative = false;
         state->branches = 1;
         state->frame[0] = kzalloc(sizeof(struct bpf_func_state), GFP_KERNEL);
         if (!state->frame[0]) {
                 kfree(state);
                 return -ENOMEM;
         }
         env->cur_state = state;
         init_func_state(env, state->frame[0],
                         BPF_MAIN_FUNC /* callsite */,
                         0 /* frameno */,
                         subprog);
         state->first_insn_idx = env->subprog_info[subprog].start;
         state->last_insn_idx = -1;
 
         regs = state->frame[state->curframe]->regs;
         if (subprog || env->prog->type == BPF_PROG_TYPE_EXT) {
                 const char *sub_name = subprog_name(env, subprog);
                 struct bpf_subprog_arg_info *arg;
                 struct bpf_reg_state *reg;
 
                 verbose(env, "Validating %s() func#%d...\n", sub_name, subprog);
                 ret = btf_prepare_func_args(env, subprog);
                 if (ret)
                         goto out;
 
                 if (subprog_is_exc_cb(env, subprog)) {
                         state->frame[0]->in_exception_callback_fn = true;
                         /* We have already ensured that the callback returns an integer, just
                          * like all global subprogs. We need to determine it only has a single
                          * scalar argument.
                          */
                         if (sub->arg_cnt != 1 || sub->args[0].arg_type != ARG_ANYTHING) {
                                 verbose(env, "exception cb only supports single integer argument\n");
                                 ret = -EINVAL;
                                 goto out;
                         }
                 }
                 for (i = BPF_REG_1; i <= sub->arg_cnt; i++) {
                         arg = &sub->args[i - BPF_REG_1];
                         reg = &regs[i];
 
                         if (arg->arg_type == ARG_PTR_TO_CTX) {
                                 reg->type = PTR_TO_CTX;
                                 mark_reg_known_zero(env, regs, i);
                         } else if (arg->arg_type == ARG_ANYTHING) {
                                 reg->type = SCALAR_VALUE;
                                 mark_reg_unknown(env, regs, i);
                         } else if (arg->arg_type == (ARG_PTR_TO_DYNPTR | MEM_RDONLY)) {
                                 /* assume unspecial LOCAL dynptr type */
                                 __mark_dynptr_reg(reg, BPF_DYNPTR_TYPE_LOCAL, true, ++env->id_gen);
                         } else if (base_type(arg->arg_type) == ARG_PTR_TO_MEM) {
                                 reg->type = PTR_TO_MEM;
                                 if (arg->arg_type & PTR_MAYBE_NULL)
                                         reg->type |= PTR_MAYBE_NULL;
                                 mark_reg_known_zero(env, regs, i);
                                 reg->mem_size = arg->mem_size;
                                 reg->id = ++env->id_gen;
                         } else if (base_type(arg->arg_type) == ARG_PTR_TO_BTF_ID) {
                                 reg->type = PTR_TO_BTF_ID;
                                 if (arg->arg_type & PTR_MAYBE_NULL)
                                         reg->type |= PTR_MAYBE_NULL;
                                 if (arg->arg_type & PTR_UNTRUSTED)
                                         reg->type |= PTR_UNTRUSTED;
                                 if (arg->arg_type & PTR_TRUSTED)
                                         reg->type |= PTR_TRUSTED;
                                 mark_reg_known_zero(env, regs, i);
                                 reg->btf = bpf_get_btf_vmlinux(); /* can't fail at this point */
                                 reg->btf_id = arg->btf_id;
                                 reg->id = ++env->id_gen;
                         } else if (base_type(arg->arg_type) == ARG_PTR_TO_ARENA) {
                                 /* caller can pass either PTR_TO_ARENA or SCALAR */
                                 mark_reg_unknown(env, regs, i);
                         } else {
                                 WARN_ONCE(1, "BUG: unhandled arg#%d type %d\n",
                                           i - BPF_REG_1, arg->arg_type);
                                 ret = -EFAULT;
                                 goto out;
                         }
                 }
         } else {
                 /* if main BPF program has associated BTF info, validate that
                  * it's matching expected signature, and otherwise mark BTF
                  * info for main program as unreliable
                  */
                 if (env->prog->aux->func_info_aux) {
                         ret = btf_prepare_func_args(env, 0);
                         if (ret || sub->arg_cnt != 1 || sub->args[0].arg_type != ARG_PTR_TO_CTX)
                                 env->prog->aux->func_info_aux[0].unreliable = true;
                 }
 
                 /* 1st arg to a function */
                 regs[BPF_REG_1].type = PTR_TO_CTX;
                 mark_reg_known_zero(env, regs, BPF_REG_1);
         }
 
         ret = do_check(env);
 out:
         /* check for NULL is necessary, since cur_state can be freed inside
          * do_check() under memory pressure.
          */
         if (env->cur_state) {
                 free_verifier_state(env->cur_state, true);
                 env->cur_state = NULL;
         }
         while (!pop_stack(env, NULL, NULL, false));
         if (!ret && pop_log)
                 bpf_vlog_reset(&env->log, 0);
         free_states(env);
         return ret;
 }
 
 /* Lazily verify all global functions based on their BTF, if they are called
  * from main BPF program or any of subprograms transitively.
  * BPF global subprogs called from dead code are not validated.
  * All callable global functions must pass verification.
  * Otherwise the whole program is rejected.
  * Consider:
  * int bar(int);
  * int foo(int f)
  * {
  *    return bar(f);
  * }
  * int bar(int b)
  * {
  *    ...
  * }
  * foo() will be verified first for R1=any_scalar_value. During verification it
  * will be assumed that bar() already verified successfully and call to bar()
  * from foo() will be checked for type match only. Later bar() will be verified
  * independently to check that it's safe for R1=any_scalar_value.
  */
 static int do_check_subprogs(struct bpf_verifier_env *env)
 {
         struct bpf_prog_aux *aux = env->prog->aux;
         struct bpf_func_info_aux *sub_aux;
         int i, ret, new_cnt;
 
         if (!aux->func_info)
                 return 0;
 
         /* exception callback is presumed to be always called */
         if (env->exception_callback_subprog)
                 subprog_aux(env, env->exception_callback_subprog)->called = true;
 
 again:
         new_cnt = 0;
         for (i = 1; i < env->subprog_cnt; i++) {
                 if (!subprog_is_global(env, i))
                         continue;
 
                 sub_aux = subprog_aux(env, i);
                 if (!sub_aux->called || sub_aux->verified)
                         continue;
 
                 env->insn_idx = env->subprog_info[i].start;
                 WARN_ON_ONCE(env->insn_idx == 0);
                 ret = do_check_common(env, i);
                 if (ret) {
                         return ret;
                 } else if (env->log.level & BPF_LOG_LEVEL) {
                         verbose(env, "Func#%d ('%s') is safe for any args that match its prototype\n",
                                 i, subprog_name(env, i));
                 }
 
                 /* We verified new global subprog, it might have called some
                  * more global subprogs that we haven't verified yet, so we
                  * need to do another pass over subprogs to verify those.
                  */
                 sub_aux->verified = true;
                 new_cnt++;
         }
 
         /* We can't loop forever as we verify at least one global subprog on
          * each pass.
          */
         if (new_cnt)
                 goto again;
 
         return 0;
 }
 
 static int do_check_main(struct bpf_verifier_env *env)
 {
         int ret;
 
         env->insn_idx = 0;
         ret = do_check_common(env, 0);
         if (!ret)
                 env->prog->aux->stack_depth = env->subprog_info[0].stack_depth;
         return ret;
 }
 
 
 static void print_verification_stats(struct bpf_verifier_env *env)
 {
         int i;
 
         if (env->log.level & BPF_LOG_STATS) {
                 verbose(env, "verification time %lld usec\n",
                         div_u64(env->verification_time, 1000));
                 verbose(env, "stack depth ");
                 for (i = 0; i < env->subprog_cnt; i++) {
                         u32 depth = env->subprog_info[i].stack_depth;
 
                         verbose(env, "%d", depth);
                         if (i + 1 < env->subprog_cnt)
                                 verbose(env, "+");
                 }
                 verbose(env, "\n");
         }
         verbose(env, "processed %d insns (limit %d) max_states_per_insn %d "
                 "total_states %d peak_states %d mark_read %d\n",
                 env->insn_processed, BPF_COMPLEXITY_LIMIT_INSNS,
                 env->max_states_per_insn, env->total_states,
                 env->peak_states, env->longest_mark_read_walk);
 }
 
 static int check_struct_ops_btf_id(struct bpf_verifier_env *env)
 {
         const struct btf_type *t, *func_proto;
         const struct bpf_struct_ops_desc *st_ops_desc;
         const struct bpf_struct_ops *st_ops;
         const struct btf_member *member;
         struct bpf_prog *prog = env->prog;
         u32 btf_id, member_idx;
         struct btf *btf;
         const char *mname;
 
         if (!prog->gpl_compatible) {
                 verbose(env, "struct ops programs must have a GPL compatible license\n");
                 return -EINVAL;
         }
 
         if (!prog->aux->attach_btf_id)
                 return -ENOTSUPP;
 
         btf = prog->aux->attach_btf;
         if (btf_is_module(btf)) {
                 /* Make sure st_ops is valid through the lifetime of env */
                 env->attach_btf_mod = btf_try_get_module(btf);
                 if (!env->attach_btf_mod) {
                         verbose(env, "struct_ops module %s is not found\n",
                                 btf_get_name(btf));
                         return -ENOTSUPP;
                 }
         }
 
         btf_id = prog->aux->attach_btf_id;
         st_ops_desc = bpf_struct_ops_find(btf, btf_id);
         if (!st_ops_desc) {
                 verbose(env, "attach_btf_id %u is not a supported struct\n",
                         btf_id);
                 return -ENOTSUPP;
         }
         st_ops = st_ops_desc->st_ops;
 
         t = st_ops_desc->type;
         member_idx = prog->expected_attach_type;
         if (member_idx >= btf_type_vlen(t)) {
                 verbose(env, "attach to invalid member idx %u of struct %s\n",
                         member_idx, st_ops->name);
                 return -EINVAL;
         }
 
         member = &btf_type_member(t)[member_idx];
         mname = btf_name_by_offset(btf, member->name_off);
         func_proto = btf_type_resolve_func_ptr(btf, member->type,
                                                NULL);
         if (!func_proto) {
                 verbose(env, "attach to invalid member %s(@idx %u) of struct %s\n",
                         mname, member_idx, st_ops->name);
                 return -EINVAL;
         }
 
         if (st_ops->check_member) {
                 int err = st_ops->check_member(t, member, prog);
 
                 if (err) {
                         verbose(env, "attach to unsupported member %s of struct %s\n",
                                 mname, st_ops->name);
                         return err;
                 }
         }
 
         /* btf_ctx_access() used this to provide argument type info */
         prog->aux->ctx_arg_info =
                 st_ops_desc->arg_info[member_idx].info;
         prog->aux->ctx_arg_info_size =
                 st_ops_desc->arg_info[member_idx].cnt;
 
         prog->aux->attach_func_proto = func_proto;
         prog->aux->attach_func_name = mname;
         env->ops = st_ops->verifier_ops;
 
         return 0;
 }
 #define SECURITY_PREFIX "security_"
 
 static int check_attach_modify_return(unsigned long addr, const char *func_name)
 {
         if (within_error_injection_list(addr) ||
             !strncmp(SECURITY_PREFIX, func_name, sizeof(SECURITY_PREFIX) - 1))
                 return 0;
 
         return -EINVAL;
 }
 
 /* list of non-sleepable functions that are otherwise on
  * ALLOW_ERROR_INJECTION list
  */
 BTF_SET_START(btf_non_sleepable_error_inject)
 /* Three functions below can be called from sleepable and non-sleepable context.
  * Assume non-sleepable from bpf safety point of view.
  */
 BTF_ID(func, __filemap_add_folio)
 #ifdef CONFIG_FAIL_PAGE_ALLOC
 BTF_ID(func, should_fail_alloc_page)
 #endif
 #ifdef CONFIG_FAILSLAB
 BTF_ID(func, should_failslab)
 #endif
 BTF_SET_END(btf_non_sleepable_error_inject)
 
 static int check_non_sleepable_error_inject(u32 btf_id)
 {
         return btf_id_set_contains(&btf_non_sleepable_error_inject, btf_id);
 }
 
 int bpf_check_attach_target(struct bpf_verifier_log *log,
                             const struct bpf_prog *prog,
                             const struct bpf_prog *tgt_prog,
                             u32 btf_id,
                             struct bpf_attach_target_info *tgt_info)
 {
         bool prog_extension = prog->type == BPF_PROG_TYPE_EXT;
         bool prog_tracing = prog->type == BPF_PROG_TYPE_TRACING;
         const char prefix[] = "btf_trace_";
         int ret = 0, subprog = -1, i;
         const struct btf_type *t;
         bool conservative = true;
         const char *tname;
         struct btf *btf;
         long addr = 0;
         struct module *mod = NULL;
 
         if (!btf_id) {
                 bpf_log(log, "Tracing programs must provide btf_id\n");
                 return -EINVAL;
         }
         btf = tgt_prog ? tgt_prog->aux->btf : prog->aux->attach_btf;
         if (!btf) {
                 bpf_log(log,
                         "FENTRY/FEXIT program can only be attached to another program annotated with BTF\n");
                 return -EINVAL;
         }
         t = btf_type_by_id(btf, btf_id);
         if (!t) {
                 bpf_log(log, "attach_btf_id %u is invalid\n", btf_id);
                 return -EINVAL;
         }
         tname = btf_name_by_offset(btf, t->name_off);
         if (!tname) {
                 bpf_log(log, "attach_btf_id %u doesn't have a name\n", btf_id);
                 return -EINVAL;
         }
         if (tgt_prog) {
                 struct bpf_prog_aux *aux = tgt_prog->aux;
 
                 if (bpf_prog_is_dev_bound(prog->aux) &&
                     !bpf_prog_dev_bound_match(prog, tgt_prog)) {
                         bpf_log(log, "Target program bound device mismatch");
                         return -EINVAL;
                 }
 
                 for (i = 0; i < aux->func_info_cnt; i++)
                         if (aux->func_info[i].type_id == btf_id) {
                                 subprog = i;
                                 break;
                         }
                 if (subprog == -1) {
                         bpf_log(log, "Subprog %s doesn't exist\n", tname);
                         return -EINVAL;
                 }
                 if (aux->func && aux->func[subprog]->aux->exception_cb) {
                         bpf_log(log,
                                 "%s programs cannot attach to exception callback\n",
                                 prog_extension ? "Extension" : "FENTRY/FEXIT");
                         return -EINVAL;
                 }
                 conservative = aux->func_info_aux[subprog].unreliable;
                 if (prog_extension) {
                         if (conservative) {
                                 bpf_log(log,
                                         "Cannot replace static functions\n");
                                 return -EINVAL;
                         }
                         if (!prog->jit_requested) {
                                 bpf_log(log,
                                         "Extension programs should be JITed\n");
                                 return -EINVAL;
                         }
                 }
                 if (!tgt_prog->jited) {
                         bpf_log(log, "Can attach to only JITed progs\n");
                         return -EINVAL;
                 }
                 if (prog_tracing) {
                         if (aux->attach_tracing_prog) {
                                 /*
                                  * Target program is an fentry/fexit which is already attached
                                  * to another tracing program. More levels of nesting
                                  * attachment are not allowed.
                                  */
                                 bpf_log(log, "Cannot nest tracing program attach more than once\n");
                                 return -EINVAL;
                         }
                 } else if (tgt_prog->type == prog->type) {
                         /*
                          * To avoid potential call chain cycles, prevent attaching of a
                          * program extension to another extension. It's ok to attach
                          * fentry/fexit to extension program.
                          */
                         bpf_log(log, "Cannot recursively attach\n");
                         return -EINVAL;
                 }
                 if (tgt_prog->type == BPF_PROG_TYPE_TRACING &&
                     prog_extension &&
                     (tgt_prog->expected_attach_type == BPF_TRACE_FENTRY ||
                      tgt_prog->expected_attach_type == BPF_TRACE_FEXIT)) {
                         /* Program extensions can extend all program types
                          * except fentry/fexit. The reason is the following.
                          * The fentry/fexit programs are used for performance
                          * analysis, stats and can be attached to any program
                          * type. When extension program is replacing XDP function
                          * it is necessary to allow performance analysis of all
                          * functions. Both original XDP program and its program
                          * extension. Hence attaching fentry/fexit to
                          * BPF_PROG_TYPE_EXT is allowed. If extending of
                          * fentry/fexit was allowed it would be possible to create
                          * long call chain fentry->extension->fentry->extension
                          * beyond reasonable stack size. Hence extending fentry
                          * is not allowed.
                          */
                         bpf_log(log, "Cannot extend fentry/fexit\n");
                         return -EINVAL;
                 }
         } else {
                 if (prog_extension) {
                         bpf_log(log, "Cannot replace kernel functions\n");
                         return -EINVAL;
                 }
         }
 
         switch (prog->expected_attach_type) {
         case BPF_TRACE_RAW_TP:
                 if (tgt_prog) {
                         bpf_log(log,
                                 "Only FENTRY/FEXIT progs are attachable to another BPF prog\n");
                         return -EINVAL;
                 }
                 if (!btf_type_is_typedef(t)) {
                         bpf_log(log, "attach_btf_id %u is not a typedef\n",
                                 btf_id);
                         return -EINVAL;
                 }
                 if (strncmp(prefix, tname, sizeof(prefix) - 1)) {
                         bpf_log(log, "attach_btf_id %u points to wrong type name %s\n",
                                 btf_id, tname);
                         return -EINVAL;
                 }
                 tname += sizeof(prefix) - 1;
                 t = btf_type_by_id(btf, t->type);
                 if (!btf_type_is_ptr(t))
                         /* should never happen in valid vmlinux build */
                         return -EINVAL;
                 t = btf_type_by_id(btf, t->type);
                 if (!btf_type_is_func_proto(t))
                         /* should never happen in valid vmlinux build */
                         return -EINVAL;
 
                 break;
         case BPF_TRACE_ITER:
                 if (!btf_type_is_func(t)) {
                         bpf_log(log, "attach_btf_id %u is not a function\n",
                                 btf_id);
                         return -EINVAL;
                 }
                 t = btf_type_by_id(btf, t->type);
                 if (!btf_type_is_func_proto(t))
                         return -EINVAL;
                 ret = btf_distill_func_proto(log, btf, t, tname, &tgt_info->fmodel);
                 if (ret)
                         return ret;
                 break;
         default:
                 if (!prog_extension)
                         return -EINVAL;
                 fallthrough;
         case BPF_MODIFY_RETURN:
         case BPF_LSM_MAC:
         case BPF_LSM_CGROUP:
         case BPF_TRACE_FENTRY:
         case BPF_TRACE_FEXIT:
                 if (!btf_type_is_func(t)) {
                         bpf_log(log, "attach_btf_id %u is not a function\n",
                                 btf_id);
                         return -EINVAL;
                 }
                 if (prog_extension &&
                     btf_check_type_match(log, prog, btf, t))
                         return -EINVAL;
                 t = btf_type_by_id(btf, t->type);
                 if (!btf_type_is_func_proto(t))
                         return -EINVAL;
 
                 if ((prog->aux->saved_dst_prog_type || prog->aux->saved_dst_attach_type) &&
                     (!tgt_prog || prog->aux->saved_dst_prog_type != tgt_prog->type ||
                      prog->aux->saved_dst_attach_type != tgt_prog->expected_attach_type))
                         return -EINVAL;
 
                 if (tgt_prog && conservative)
                         t = NULL;
 
                 ret = btf_distill_func_proto(log, btf, t, tname, &tgt_info->fmodel);
                 if (ret < 0)
                         return ret;
 
                 if (tgt_prog) {
                         if (subprog == 0)
                                 addr = (long) tgt_prog->bpf_func;
                         else
                                 addr = (long) tgt_prog->aux->func[subprog]->bpf_func;
                 } else {
                         if (btf_is_module(btf)) {
                                 mod = btf_try_get_module(btf);
                                 if (mod)
                                         addr = find_kallsyms_symbol_value(mod, tname);
                                 else
                                         addr = 0;
                         } else {
                                 addr = kallsyms_lookup_name(tname);
                         }
                         if (!addr) {
                                 module_put(mod);
                                 bpf_log(log,
                                         "The address of function %s cannot be found\n",
                                         tname);
                                 return -ENOENT;
                         }
                 }
 
                 if (prog->sleepable) {
                         ret = -EINVAL;
                         switch (prog->type) {
                         case BPF_PROG_TYPE_TRACING:
 
                                 /* fentry/fexit/fmod_ret progs can be sleepable if they are
                                  * attached to ALLOW_ERROR_INJECTION and are not in denylist.
                                  */
                                 if (!check_non_sleepable_error_inject(btf_id) &&
                                     within_error_injection_list(addr))
                                         ret = 0;
                                 /* fentry/fexit/fmod_ret progs can also be sleepable if they are
                                  * in the fmodret id set with the KF_SLEEPABLE flag.
                                  */
                                 else {
                                         u32 *flags = btf_kfunc_is_modify_return(btf, btf_id,
                                                                                 prog);
 
                                         if (flags && (*flags & KF_SLEEPABLE))
                                                 ret = 0;
                                 }
                                 break;
                         case BPF_PROG_TYPE_LSM:
                                 /* LSM progs check that they are attached to bpf_lsm_*() funcs.
                                  * Only some of them are sleepable.
                                  */
                                 if (bpf_lsm_is_sleepable_hook(btf_id))
                                         ret = 0;
                                 break;
                         default:
                                 break;
                         }
                         if (ret) {
                                 module_put(mod);
                                 bpf_log(log, "%s is not sleepable\n", tname);
                                 return ret;
                         }
                 } else if (prog->expected_attach_type == BPF_MODIFY_RETURN) {
                         if (tgt_prog) {
                                 module_put(mod);
                                 bpf_log(log, "can't modify return codes of BPF programs\n");
                                 return -EINVAL;
                         }
                         ret = -EINVAL;
                         if (btf_kfunc_is_modify_return(btf, btf_id, prog) ||
                             !check_attach_modify_return(addr, tname))
                                 ret = 0;
                         if (ret) {
                                 module_put(mod);
                                 bpf_log(log, "%s() is not modifiable\n", tname);
                                 return ret;
                         }
                 }
 
                 break;
         }
         tgt_info->tgt_addr = addr;
         tgt_info->tgt_name = tname;
         tgt_info->tgt_type = t;
         tgt_info->tgt_mod = mod;
         return 0;
 }
 
 BTF_SET_START(btf_id_deny)
 BTF_ID_UNUSED
 #ifdef CONFIG_SMP
 BTF_ID(func, migrate_disable)
 BTF_ID(func, migrate_enable)
 #endif
 #if !defined CONFIG_PREEMPT_RCU && !defined CONFIG_TINY_RCU
 BTF_ID(func, rcu_read_unlock_strict)
 #endif
 #if defined(CONFIG_DEBUG_PREEMPT) || defined(CONFIG_TRACE_PREEMPT_TOGGLE)
 BTF_ID(func, preempt_count_add)
 BTF_ID(func, preempt_count_sub)
 #endif
 #ifdef CONFIG_PREEMPT_RCU
 BTF_ID(func, __rcu_read_lock)
 BTF_ID(func, __rcu_read_unlock)
 #endif
 BTF_SET_END(btf_id_deny)
 
 static bool can_be_sleepable(struct bpf_prog *prog)
 {
         if (prog->type == BPF_PROG_TYPE_TRACING) {
                 switch (prog->expected_attach_type) {
                 case BPF_TRACE_FENTRY:
                 case BPF_TRACE_FEXIT:
                 case BPF_MODIFY_RETURN:
                 case BPF_TRACE_ITER:
                         return true;
                 default:
                         return false;
                 }
         }
         return prog->type == BPF_PROG_TYPE_LSM ||
                prog->type == BPF_PROG_TYPE_KPROBE /* only for uprobes */ ||
                prog->type == BPF_PROG_TYPE_STRUCT_OPS;
 }
 
 static int check_attach_btf_id(struct bpf_verifier_env *env)
 {
         struct bpf_prog *prog = env->prog;
         struct bpf_prog *tgt_prog = prog->aux->dst_prog;
         struct bpf_attach_target_info tgt_info = {};
         u32 btf_id = prog->aux->attach_btf_id;
         struct bpf_trampoline *tr;
         int ret;
         u64 key;
 
         if (prog->type == BPF_PROG_TYPE_SYSCALL) {
                 if (prog->sleepable)
                         /* attach_btf_id checked to be zero already */
                         return 0;
                 verbose(env, "Syscall programs can only be sleepable\n");
                 return -EINVAL;
         }
 
         if (prog->sleepable && !can_be_sleepable(prog)) {
                 verbose(env, "Only fentry/fexit/fmod_ret, lsm, iter, uprobe, and struct_ops programs can be sleepable\n");
                 return -EINVAL;
         }
 
         if (prog->type == BPF_PROG_TYPE_STRUCT_OPS)
                 return check_struct_ops_btf_id(env);
 
         if (prog->type != BPF_PROG_TYPE_TRACING &&
             prog->type != BPF_PROG_TYPE_LSM &&
             prog->type != BPF_PROG_TYPE_EXT)
                 return 0;
 
         ret = bpf_check_attach_target(&env->log, prog, tgt_prog, btf_id, &tgt_info);
         if (ret)
                 return ret;
 
         if (tgt_prog && prog->type == BPF_PROG_TYPE_EXT) {
                 /* to make freplace equivalent to their targets, they need to
                  * inherit env->ops and expected_attach_type for the rest of the
                  * verification
                  */
                 env->ops = bpf_verifier_ops[tgt_prog->type];
                 prog->expected_attach_type = tgt_prog->expected_attach_type;
         }
 
         /* store info about the attachment target that will be used later */
         prog->aux->attach_func_proto = tgt_info.tgt_type;
         prog->aux->attach_func_name = tgt_info.tgt_name;
         prog->aux->mod = tgt_info.tgt_mod;
 
         if (tgt_prog) {
                 prog->aux->saved_dst_prog_type = tgt_prog->type;
                 prog->aux->saved_dst_attach_type = tgt_prog->expected_attach_type;
         }
 
         if (prog->expected_attach_type == BPF_TRACE_RAW_TP) {
                 prog->aux->attach_btf_trace = true;
                 return 0;
         } else if (prog->expected_attach_type == BPF_TRACE_ITER) {
                 if (!bpf_iter_prog_supported(prog))
                         return -EINVAL;
                 return 0;
         }
 
         if (prog->type == BPF_PROG_TYPE_LSM) {
                 ret = bpf_lsm_verify_prog(&env->log, prog);
                 if (ret < 0)
                         return ret;
         } else if (prog->type == BPF_PROG_TYPE_TRACING &&
                    btf_id_set_contains(&btf_id_deny, btf_id)) {
                 return -EINVAL;
         }
 
         key = bpf_trampoline_compute_key(tgt_prog, prog->aux->attach_btf, btf_id);
         tr = bpf_trampoline_get(key, &tgt_info);
         if (!tr)
                 return -ENOMEM;
 
         if (tgt_prog && tgt_prog->aux->tail_call_reachable)
                 tr->flags = BPF_TRAMP_F_TAIL_CALL_CTX;
 
         prog->aux->dst_trampoline = tr;
         return 0;
 }
 
 struct btf *bpf_get_btf_vmlinux(void)
 {
         if (!btf_vmlinux && IS_ENABLED(CONFIG_DEBUG_INFO_BTF)) {
                 mutex_lock(&bpf_verifier_lock);
                 if (!btf_vmlinux)
                         btf_vmlinux = btf_parse_vmlinux();
                 mutex_unlock(&bpf_verifier_lock);
         }
         return btf_vmlinux;
 }
 
 int bpf_check(struct bpf_prog **prog, union bpf_attr *attr, bpfptr_t uattr, __u32 uattr_size)
 {
         u64 start_time = ktime_get_ns();
         struct bpf_verifier_env *env;
         int i, len, ret = -EINVAL, err;
         u32 log_true_size;
         bool is_priv;
 
         /* no program is valid */
         if (ARRAY_SIZE(bpf_verifier_ops) == 0)
                 return -EINVAL;
 
         /* 'struct bpf_verifier_env' can be global, but since it's not small,
          * allocate/free it every time bpf_check() is called
          */
         env = kzalloc(sizeof(struct bpf_verifier_env), GFP_KERNEL);
         if (!env)
                 return -ENOMEM;
 
         env->bt.env = env;
 
         len = (*prog)->len;
         env->insn_aux_data =
                 vzalloc(array_size(sizeof(struct bpf_insn_aux_data), len));
         ret = -ENOMEM;
         if (!env->insn_aux_data)
                 goto err_free_env;
         for (i = 0; i < len; i++)
                 env->insn_aux_data[i].orig_idx = i;
         env->prog = *prog;
         env->ops = bpf_verifier_ops[env->prog->type];
         env->fd_array = make_bpfptr(attr->fd_array, uattr.is_kernel);
 
         env->allow_ptr_leaks = bpf_allow_ptr_leaks(env->prog->aux->token);
         env->allow_uninit_stack = bpf_allow_uninit_stack(env->prog->aux->token);
         env->bypass_spec_v1 = bpf_bypass_spec_v1(env->prog->aux->token);
         env->bypass_spec_v4 = bpf_bypass_spec_v4(env->prog->aux->token);
         env->bpf_capable = is_priv = bpf_token_capable(env->prog->aux->token, CAP_BPF);
 
         bpf_get_btf_vmlinux();
 
         /* grab the mutex to protect few globals used by verifier */
         if (!is_priv)
                 mutex_lock(&bpf_verifier_lock);
 
         /* user could have requested verbose verifier output
          * and supplied buffer to store the verification trace
          */
         ret = bpf_vlog_init(&env->log, attr->log_level,
                             (char __user *) (unsigned long) attr->log_buf,
                             attr->log_size);
         if (ret)
                 goto err_unlock;
 
         mark_verifier_state_clean(env);
 
         if (IS_ERR(btf_vmlinux)) {
                 /* Either gcc or pahole or kernel are broken. */
                 verbose(env, "in-kernel BTF is malformed\n");
                 ret = PTR_ERR(btf_vmlinux);
                 goto skip_full_check;
         }
 
         env->strict_alignment = !!(attr->prog_flags & BPF_F_STRICT_ALIGNMENT);
         if (!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS))
                 env->strict_alignment = true;
         if (attr->prog_flags & BPF_F_ANY_ALIGNMENT)
                 env->strict_alignment = false;
 
         if (is_priv)
                 env->test_state_freq = attr->prog_flags & BPF_F_TEST_STATE_FREQ;
         env->test_reg_invariants = attr->prog_flags & BPF_F_TEST_REG_INVARIANTS;
 
         env->explored_states = kvcalloc(state_htab_size(env),
                                        sizeof(struct bpf_verifier_state_list *),
                                        GFP_USER);
         ret = -ENOMEM;
         if (!env->explored_states)
                 goto skip_full_check;
 
         ret = check_btf_info_early(env, attr, uattr);
         if (ret < 0)
                 goto skip_full_check;
 
         ret = add_subprog_and_kfunc(env);
         if (ret < 0)
                 goto skip_full_check;
 
         ret = check_subprogs(env);
         if (ret < 0)
                 goto skip_full_check;
 
         ret = check_btf_info(env, attr, uattr);
         if (ret < 0)
                 goto skip_full_check;
 
         ret = check_attach_btf_id(env);
         if (ret)
                 goto skip_full_check;
 
         ret = resolve_pseudo_ldimm64(env);
         if (ret < 0)
                 goto skip_full_check;
 
         if (bpf_prog_is_offloaded(env->prog->aux)) {
                 ret = bpf_prog_offload_verifier_prep(env->prog);
                 if (ret)
                         goto skip_full_check;
         }
 
         ret = check_cfg(env);
         if (ret < 0)
                 goto skip_full_check;
 
         ret = do_check_main(env);
         ret = ret ?: do_check_subprogs(env);
 
         if (ret == 0 && bpf_prog_is_offloaded(env->prog->aux))
                 ret = bpf_prog_offload_finalize(env);
 
 skip_full_check:
         kvfree(env->explored_states);
 
         if (ret == 0)
                 ret = check_max_stack_depth(env);
 
         /* instruction rewrites happen after this point */
         if (ret == 0)
                 ret = optimize_bpf_loop(env);
 
         if (is_priv) {
                 if (ret == 0)
                         opt_hard_wire_dead_code_branches(env);
                 if (ret == 0)
                         ret = opt_remove_dead_code(env);
                 if (ret == 0)
                         ret = opt_remove_nops(env);
         } else {
                 if (ret == 0)
                         sanitize_dead_code(env);
         }
 
         if (ret == 0)
                 /* program is valid, convert *(u32*)(ctx + off) accesses */
                 ret = convert_ctx_accesses(env);
 
         if (ret == 0)
                 ret = do_misc_fixups(env);
 
         /* do 32-bit optimization after insn patching has done so those patched
          * insns could be handled correctly.
          */
         if (ret == 0 && !bpf_prog_is_offloaded(env->prog->aux)) {
                 ret = opt_subreg_zext_lo32_rnd_hi32(env, attr);
                 env->prog->aux->verifier_zext = bpf_jit_needs_zext() ? !ret
                                                                      : false;
         }
 
         if (ret == 0)
                 ret = fixup_call_args(env);
 
         env->verification_time = ktime_get_ns() - start_time;
         print_verification_stats(env);
         env->prog->aux->verified_insns = env->insn_processed;
 
         /* preserve original error even if log finalization is successful */
         err = bpf_vlog_finalize(&env->log, &log_true_size);
         if (err)
                 ret = err;
 
         if (uattr_size >= offsetofend(union bpf_attr, log_true_size) &&
             copy_to_bpfptr_offset(uattr, offsetof(union bpf_attr, log_true_size),
                                   &log_true_size, sizeof(log_true_size))) {
                 ret = -EFAULT;
                 goto err_release_maps;
         }
 
         if (ret)
                 goto err_release_maps;
 
         if (env->used_map_cnt) {
                 /* if program passed verifier, update used_maps in bpf_prog_info */
                 env->prog->aux->used_maps = kmalloc_array(env->used_map_cnt,
                                                           sizeof(env->used_maps[0]),
                                                           GFP_KERNEL);
 
                 if (!env->prog->aux->used_maps) {
                         ret = -ENOMEM;
                         goto err_release_maps;
                 }
 
                 memcpy(env->prog->aux->used_maps, env->used_maps,
                        sizeof(env->used_maps[0]) * env->used_map_cnt);
                 env->prog->aux->used_map_cnt = env->used_map_cnt;
         }
         if (env->used_btf_cnt) {
                 /* if program passed verifier, update used_btfs in bpf_prog_aux */
                 env->prog->aux->used_btfs = kmalloc_array(env->used_btf_cnt,
                                                           sizeof(env->used_btfs[0]),
                                                           GFP_KERNEL);
                 if (!env->prog->aux->used_btfs) {
                         ret = -ENOMEM;
                         goto err_release_maps;
                 }
 
                 memcpy(env->prog->aux->used_btfs, env->used_btfs,
                        sizeof(env->used_btfs[0]) * env->used_btf_cnt);
                 env->prog->aux->used_btf_cnt = env->used_btf_cnt;
         }
         if (env->used_map_cnt || env->used_btf_cnt) {
                 /* program is valid. Convert pseudo bpf_ld_imm64 into generic
                  * bpf_ld_imm64 instructions
                  */
                 convert_pseudo_ld_imm64(env);
         }
 
         adjust_btf_func(env);
 
 err_release_maps:
         if (!env->prog->aux->used_maps)
                 /* if we didn't copy map pointers into bpf_prog_info, release
                  * them now. Otherwise free_used_maps() will release them.
                  */
                 release_maps(env);
         if (!env->prog->aux->used_btfs)
                 release_btfs(env);
 
         /* extension progs temporarily inherit the attach_type of their targets
            for verification purposes, so set it back to zero before returning
          */
         if (env->prog->type == BPF_PROG_TYPE_EXT)
                 env->prog->expected_attach_type = 0;
 
         *prog = env->prog;
 
         module_put(env->attach_btf_mod);
 err_unlock:
         if (!is_priv)
                 mutex_unlock(&bpf_verifier_lock);
         vfree(env->insn_aux_data);
 err_free_env:
         kfree(env);
         return ret;
 }