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
7struct map_elem {
8	struct bpf_timer timer;
9	struct bpf_spin_lock lock;
10};
11
12struct {
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
19struct {
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
26int pid = 0;
27int crash_map = 0; /* 0 for amap, 1 for hmap */
28
29SEC("fentry/do_nanosleep")
30int 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
54char _license[] SEC("license") = "GPL";
55