1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * UBSAN error reporting functions
4 *
5 * Copyright (c) 2014 Samsung Electronics Co., Ltd.
6 * Author: Andrey Ryabinin <ryabinin.a.a@gmail.com>
7 */
8
9 #include <linux/bitops.h>
10 #include <linux/bug.h>
11 #include <linux/ctype.h>
12 #include <linux/init.h>
13 #include <linux/kernel.h>
14 #include <linux/types.h>
15 #include <linux/sched.h>
16 #include <linux/uaccess.h>
17 #include <linux/ubsan.h>
18 #include <kunit/test-bug.h>
19
20 #include "ubsan.h"
21
22 #ifdef CONFIG_UBSAN_TRAP
23 /*
24 * Only include matches for UBSAN checks that are actually compiled in.
25 * The mappings of struct SanitizerKind (the -fsanitize=xxx args) to
26 * enum SanitizerHandler (the traps) in Clang is in clang/lib/CodeGen/.
27 */
28 const char *report_ubsan_failure(struct pt_regs *regs, u32 check_type)
29 {
30 switch (check_type) {
31 #ifdef CONFIG_UBSAN_BOUNDS
32 /*
33 * SanitizerKind::ArrayBounds and SanitizerKind::LocalBounds
34 * emit SanitizerHandler::OutOfBounds.
35 */
36 case ubsan_out_of_bounds:
37 return "UBSAN: array index out of bounds";
38 #endif
39 #ifdef CONFIG_UBSAN_SHIFT
40 /*
41 * SanitizerKind::ShiftBase and SanitizerKind::ShiftExponent
42 * emit SanitizerHandler::ShiftOutOfBounds.
43 */
44 case ubsan_shift_out_of_bounds:
45 return "UBSAN: shift out of bounds";
46 #endif
47 #if defined(CONFIG_UBSAN_DIV_ZERO) || defined(CONFIG_UBSAN_SIGNED_WRAP)
48 /*
49 * SanitizerKind::IntegerDivideByZero and
50 * SanitizerKind::SignedIntegerOverflow emit
51 * SanitizerHandler::DivremOverflow.
52 */
53 case ubsan_divrem_overflow:
54 return "UBSAN: divide/remainder overflow";
55 #endif
56 #ifdef CONFIG_UBSAN_UNREACHABLE
57 /*
58 * SanitizerKind::Unreachable emits
59 * SanitizerHandler::BuiltinUnreachable.
60 */
61 case ubsan_builtin_unreachable:
62 return "UBSAN: unreachable code";
63 #endif
64 #if defined(CONFIG_UBSAN_BOOL) || defined(CONFIG_UBSAN_ENUM)
65 /*
66 * SanitizerKind::Bool and SanitizerKind::Enum emit
67 * SanitizerHandler::LoadInvalidValue.
68 */
69 case ubsan_load_invalid_value:
70 return "UBSAN: loading invalid value";
71 #endif
72 #ifdef CONFIG_UBSAN_ALIGNMENT
73 /*
74 * SanitizerKind::Alignment emits SanitizerHandler::TypeMismatch
75 * or SanitizerHandler::AlignmentAssumption.
76 */
77 case ubsan_alignment_assumption:
78 return "UBSAN: alignment assumption";
79 case ubsan_type_mismatch:
80 return "UBSAN: type mismatch";
81 #endif
82 #ifdef CONFIG_UBSAN_SIGNED_WRAP
83 /*
84 * SanitizerKind::SignedIntegerOverflow emits
85 * SanitizerHandler::AddOverflow, SanitizerHandler::SubOverflow,
86 * or SanitizerHandler::MulOverflow.
87 */
88 case ubsan_add_overflow:
89 return "UBSAN: integer addition overflow";
90 case ubsan_sub_overflow:
91 return "UBSAN: integer subtraction overflow";
92 case ubsan_mul_overflow:
93 return "UBSAN: integer multiplication overflow";
94 #endif
95 default:
96 return "UBSAN: unrecognized failure code";
97 }
98 }
99
100 #else
101 static const char * const type_check_kinds[] = {
102 "load of",
103 "store to",
104 "reference binding to",
105 "member access within",
106 "member call on",
107 "constructor call on",
108 "downcast of",
109 "downcast of"
110 };
111
112 #define REPORTED_BIT 31
113
114 #if (BITS_PER_LONG == 64) && defined(__BIG_ENDIAN)
115 #define COLUMN_MASK (~(1U << REPORTED_BIT))
116 #define LINE_MASK (~0U)
117 #else
118 #define COLUMN_MASK (~0U)
119 #define LINE_MASK (~(1U << REPORTED_BIT))
120 #endif
121
122 #define VALUE_LENGTH 40
123
124 static bool was_reported(struct source_location *location)
125 {
126 return test_and_set_bit(REPORTED_BIT, &location->reported);
127 }
128
129 static bool suppress_report(struct source_location *loc)
130 {
131 return current->in_ubsan || was_reported(loc);
132 }
133
134 static bool type_is_int(struct type_descriptor *type)
135 {
136 return type->type_kind == type_kind_int;
137 }
138
139 static bool type_is_signed(struct type_descriptor *type)
140 {
141 WARN_ON(!type_is_int(type));
142 return type->type_info & 1;
143 }
144
145 static unsigned type_bit_width(struct type_descriptor *type)
146 {
147 return 1 << (type->type_info >> 1);
148 }
149
150 static bool is_inline_int(struct type_descriptor *type)
151 {
152 unsigned inline_bits = sizeof(unsigned long)*8;
153 unsigned bits = type_bit_width(type);
154
155 WARN_ON(!type_is_int(type));
156
157 return bits <= inline_bits;
158 }
159
160 static s_max get_signed_val(struct type_descriptor *type, void *val)
161 {
162 if (is_inline_int(type)) {
163 unsigned extra_bits = sizeof(s_max)*8 - type_bit_width(type);
164 unsigned long ulong_val = (unsigned long)val;
165
166 return ((s_max)ulong_val) << extra_bits >> extra_bits;
167 }
168
169 if (type_bit_width(type) == 64)
170 return *(s64 *)val;
171
172 return *(s_max *)val;
173 }
174
175 static bool val_is_negative(struct type_descriptor *type, void *val)
176 {
177 return type_is_signed(type) && get_signed_val(type, val) < 0;
178 }
179
180 static u_max get_unsigned_val(struct type_descriptor *type, void *val)
181 {
182 if (is_inline_int(type))
183 return (unsigned long)val;
184
185 if (type_bit_width(type) == 64)
186 return *(u64 *)val;
187
188 return *(u_max *)val;
189 }
190
191 static void val_to_string(char *str, size_t size, struct type_descriptor *type,
192 void *value)
193 {
194 if (type_is_int(type)) {
195 if (type_bit_width(type) == 128) {
196 #if defined(CONFIG_ARCH_SUPPORTS_INT128)
197 u_max val = get_unsigned_val(type, value);
198
199 scnprintf(str, size, "0x%08x%08x%08x%08x",
200 (u32)(val >> 96),
201 (u32)(val >> 64),
202 (u32)(val >> 32),
203 (u32)(val));
204 #else
205 WARN_ON(1);
206 #endif
207 } else if (type_is_signed(type)) {
208 scnprintf(str, size, "%lld",
209 (s64)get_signed_val(type, value));
210 } else {
211 scnprintf(str, size, "%llu",
212 (u64)get_unsigned_val(type, value));
213 }
214 }
215 }
216
217 static void ubsan_prologue(struct source_location *loc, const char *reason)
218 {
219 current->in_ubsan++;
220
221 pr_warn(CUT_HERE);
222
223 pr_err("UBSAN: %s in %s:%d:%d\n", reason, loc->file_name,
224 loc->line & LINE_MASK, loc->column & COLUMN_MASK);
225
226 kunit_fail_current_test("%s in %s", reason, loc->file_name);
227 }
228
229 static void ubsan_epilogue(void)
230 {
231 dump_stack();
232 pr_warn("---[ end trace ]---\n");
233
234 current->in_ubsan--;
235
236 check_panic_on_warn("UBSAN");
237 }
238
239 static void handle_overflow(struct overflow_data *data, void *lhs,
240 void *rhs, char op)
241 {
242
243 struct type_descriptor *type = data->type;
244 char lhs_val_str[VALUE_LENGTH];
245 char rhs_val_str[VALUE_LENGTH];
246
247 if (suppress_report(&data->location))
248 return;
249
250 ubsan_prologue(&data->location, type_is_signed(type) ?
251 "signed-integer-overflow" :
252 "unsigned-integer-overflow");
253
254 val_to_string(lhs_val_str, sizeof(lhs_val_str), type, lhs);
255 val_to_string(rhs_val_str, sizeof(rhs_val_str), type, rhs);
256 pr_err("%s %c %s cannot be represented in type %s\n",
257 lhs_val_str,
258 op,
259 rhs_val_str,
260 type->type_name);
261
262 ubsan_epilogue();
263 }
264
265 void __ubsan_handle_add_overflow(void *data,
266 void *lhs, void *rhs)
267 {
268
269 handle_overflow(data, lhs, rhs, '+');
270 }
271 EXPORT_SYMBOL(__ubsan_handle_add_overflow);
272
273 void __ubsan_handle_sub_overflow(void *data,
274 void *lhs, void *rhs)
275 {
276 handle_overflow(data, lhs, rhs, '-');
277 }
278 EXPORT_SYMBOL(__ubsan_handle_sub_overflow);
279
280 void __ubsan_handle_mul_overflow(void *data,
281 void *lhs, void *rhs)
282 {
283 handle_overflow(data, lhs, rhs, '*');
284 }
285 EXPORT_SYMBOL(__ubsan_handle_mul_overflow);
286
287 void __ubsan_handle_negate_overflow(void *_data, void *old_val)
288 {
289 struct overflow_data *data = _data;
290 char old_val_str[VALUE_LENGTH];
291
292 if (suppress_report(&data->location))
293 return;
294
295 ubsan_prologue(&data->location, "negation-overflow");
296
297 val_to_string(old_val_str, sizeof(old_val_str), data->type, old_val);
298
299 pr_err("negation of %s cannot be represented in type %s:\n",
300 old_val_str, data->type->type_name);
301
302 ubsan_epilogue();
303 }
304 EXPORT_SYMBOL(__ubsan_handle_negate_overflow);
305
306
307 void __ubsan_handle_divrem_overflow(void *_data, void *lhs, void *rhs)
308 {
309 struct overflow_data *data = _data;
310 char rhs_val_str[VALUE_LENGTH];
311
312 if (suppress_report(&data->location))
313 return;
314
315 ubsan_prologue(&data->location, "division-overflow");
316
317 val_to_string(rhs_val_str, sizeof(rhs_val_str), data->type, rhs);
318
319 if (type_is_signed(data->type) && get_signed_val(data->type, rhs) == -1)
320 pr_err("division of %s by -1 cannot be represented in type %s\n",
321 rhs_val_str, data->type->type_name);
322 else
323 pr_err("division by zero\n");
324
325 ubsan_epilogue();
326 }
327 EXPORT_SYMBOL(__ubsan_handle_divrem_overflow);
328
329 static void handle_null_ptr_deref(struct type_mismatch_data_common *data)
330 {
331 if (suppress_report(data->location))
332 return;
333
334 ubsan_prologue(data->location, "null-ptr-deref");
335
336 pr_err("%s null pointer of type %s\n",
337 type_check_kinds[data->type_check_kind],
338 data->type->type_name);
339
340 ubsan_epilogue();
341 }
342
343 static void handle_misaligned_access(struct type_mismatch_data_common *data,
344 unsigned long ptr)
345 {
346 if (suppress_report(data->location))
347 return;
348
349 ubsan_prologue(data->location, "misaligned-access");
350
351 pr_err("%s misaligned address %p for type %s\n",
352 type_check_kinds[data->type_check_kind],
353 (void *)ptr, data->type->type_name);
354 pr_err("which requires %ld byte alignment\n", data->alignment);
355
356 ubsan_epilogue();
357 }
358
359 static void handle_object_size_mismatch(struct type_mismatch_data_common *data,
360 unsigned long ptr)
361 {
362 if (suppress_report(data->location))
363 return;
364
365 ubsan_prologue(data->location, "object-size-mismatch");
366 pr_err("%s address %p with insufficient space\n",
367 type_check_kinds[data->type_check_kind],
368 (void *) ptr);
369 pr_err("for an object of type %s\n", data->type->type_name);
370 ubsan_epilogue();
371 }
372
373 static void ubsan_type_mismatch_common(struct type_mismatch_data_common *data,
374 unsigned long ptr)
375 {
376 unsigned long flags = user_access_save();
377
378 if (!ptr)
379 handle_null_ptr_deref(data);
380 else if (data->alignment && !IS_ALIGNED(ptr, data->alignment))
381 handle_misaligned_access(data, ptr);
382 else
383 handle_object_size_mismatch(data, ptr);
384
385 user_access_restore(flags);
386 }
387
388 void __ubsan_handle_type_mismatch(struct type_mismatch_data *data,
389 void *ptr)
390 {
391 struct type_mismatch_data_common common_data = {
392 .location = &data->location,
393 .type = data->type,
394 .alignment = data->alignment,
395 .type_check_kind = data->type_check_kind
396 };
397
398 ubsan_type_mismatch_common(&common_data, (unsigned long)ptr);
399 }
400 EXPORT_SYMBOL(__ubsan_handle_type_mismatch);
401
402 void __ubsan_handle_type_mismatch_v1(void *_data, void *ptr)
403 {
404 struct type_mismatch_data_v1 *data = _data;
405 struct type_mismatch_data_common common_data = {
406 .location = &data->location,
407 .type = data->type,
408 .alignment = 1UL << data->log_alignment,
409 .type_check_kind = data->type_check_kind
410 };
411
412 ubsan_type_mismatch_common(&common_data, (unsigned long)ptr);
413 }
414 EXPORT_SYMBOL(__ubsan_handle_type_mismatch_v1);
415
416 void __ubsan_handle_out_of_bounds(void *_data, void *index)
417 {
418 struct out_of_bounds_data *data = _data;
419 char index_str[VALUE_LENGTH];
420
421 if (suppress_report(&data->location))
422 return;
423
424 ubsan_prologue(&data->location, "array-index-out-of-bounds");
425
426 val_to_string(index_str, sizeof(index_str), data->index_type, index);
427 pr_err("index %s is out of range for type %s\n", index_str,
428 data->array_type->type_name);
429 ubsan_epilogue();
430 }
431 EXPORT_SYMBOL(__ubsan_handle_out_of_bounds);
432
433 void __ubsan_handle_shift_out_of_bounds(void *_data, void *lhs, void *rhs)
434 {
435 struct shift_out_of_bounds_data *data = _data;
436 struct type_descriptor *rhs_type = data->rhs_type;
437 struct type_descriptor *lhs_type = data->lhs_type;
438 char rhs_str[VALUE_LENGTH];
439 char lhs_str[VALUE_LENGTH];
440 unsigned long ua_flags = user_access_save();
441
442 if (suppress_report(&data->location))
443 goto out;
444
445 ubsan_prologue(&data->location, "shift-out-of-bounds");
446
447 val_to_string(rhs_str, sizeof(rhs_str), rhs_type, rhs);
448 val_to_string(lhs_str, sizeof(lhs_str), lhs_type, lhs);
449
450 if (val_is_negative(rhs_type, rhs))
451 pr_err("shift exponent %s is negative\n", rhs_str);
452
453 else if (get_unsigned_val(rhs_type, rhs) >=
454 type_bit_width(lhs_type))
455 pr_err("shift exponent %s is too large for %u-bit type %s\n",
456 rhs_str,
457 type_bit_width(lhs_type),
458 lhs_type->type_name);
459 else if (val_is_negative(lhs_type, lhs))
460 pr_err("left shift of negative value %s\n",
461 lhs_str);
462 else
463 pr_err("left shift of %s by %s places cannot be"
464 " represented in type %s\n",
465 lhs_str, rhs_str,
466 lhs_type->type_name);
467
468 ubsan_epilogue();
469 out:
470 user_access_restore(ua_flags);
471 }
472 EXPORT_SYMBOL(__ubsan_handle_shift_out_of_bounds);
473
474
475 void __ubsan_handle_builtin_unreachable(void *_data)
476 {
477 struct unreachable_data *data = _data;
478 ubsan_prologue(&data->location, "unreachable");
479 pr_err("calling __builtin_unreachable()\n");
480 ubsan_epilogue();
481 panic("can't return from __builtin_unreachable()");
482 }
483 EXPORT_SYMBOL(__ubsan_handle_builtin_unreachable);
484
485 void __ubsan_handle_load_invalid_value(void *_data, void *val)
486 {
487 struct invalid_value_data *data = _data;
488 char val_str[VALUE_LENGTH];
489 unsigned long ua_flags = user_access_save();
490
491 if (suppress_report(&data->location))
492 goto out;
493
494 ubsan_prologue(&data->location, "invalid-load");
495
496 val_to_string(val_str, sizeof(val_str), data->type, val);
497
498 pr_err("load of value %s is not a valid value for type %s\n",
499 val_str, data->type->type_name);
500
501 ubsan_epilogue();
502 out:
503 user_access_restore(ua_flags);
504 }
505 EXPORT_SYMBOL(__ubsan_handle_load_invalid_value);
506
507 void __ubsan_handle_alignment_assumption(void *_data, unsigned long ptr,
508 unsigned long align,
509 unsigned long offset)
510 {
511 struct alignment_assumption_data *data = _data;
512 unsigned long real_ptr;
513
514 if (suppress_report(&data->location))
515 return;
516
517 ubsan_prologue(&data->location, "alignment-assumption");
518
519 if (offset)
520 pr_err("assumption of %lu byte alignment (with offset of %lu byte) for pointer of type %s failed",
521 align, offset, data->type->type_name);
522 else
523 pr_err("assumption of %lu byte alignment for pointer of type %s failed",
524 align, data->type->type_name);
525
526 real_ptr = ptr - offset;
527 pr_err("%saddress is %lu aligned, misalignment offset is %lu bytes",
528 offset ? "offset " : "", BIT(real_ptr ? __ffs(real_ptr) : 0),
529 real_ptr & (align - 1));
530
531 ubsan_epilogue();
532 }
533 EXPORT_SYMBOL(__ubsan_handle_alignment_assumption);
534
535 #endif /* !CONFIG_UBSAN_TRAP */
536
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