1 // SPDX-License-Identifier: GPL-2.0
2
3 #include <vmlinux.h>
4 #include <bpf/bpf_tracing.h>
5 #include <bpf/bpf_helpers.h>
6
7 struct map_elem {
8 struct bpf_timer timer;
9 struct bpf_spin_lock lock;
10 };
11
12 struct {
13 __uint(type, BPF_MAP_TYPE_ARRAY);
14 __uint(max_entries, 1);
15 __type(key, int);
16 __type(value, struct map_elem);
17 } amap SEC(".maps");
18
19 struct {
20 __uint(type, BPF_MAP_TYPE_HASH);
21 __uint(max_entries, 1);
22 __type(key, int);
23 __type(value, struct map_elem);
24 } hmap SEC(".maps");
25
26 int pid = 0;
27 int crash_map = 0; /* 0 for amap, 1 for hmap */
28
29 SEC("fentry/do_nanosleep")
30 int sys_enter(void *ctx)
31 {
32 struct map_elem *e, value = {};
33 void *map = crash_map ? (void *)&hmap : (void *)&amap;
34
35 if (bpf_get_current_task_btf()->tgid != pid)
36 return 0;
37
38 *(void **)&value = (void *)0xdeadcaf3;
39
40 bpf_map_update_elem(map, &(int){0}, &value, 0);
41 /* For array map, doing bpf_map_update_elem will do a
42 * check_and_free_timer_in_array, which will trigger the crash if timer
43 * pointer was overwritten, for hmap we need to use bpf_timer_cancel.
44 */
45 if (crash_map == 1) {
46 e = bpf_map_lookup_elem(map, &(int){0});
47 if (!e)
48 return 0;
49 bpf_timer_cancel(&e->timer);
50 }
51 return 0;
52 }
53
54 char _license[] SEC("license") = "GPL";
55
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