task_work_fail.c

 1// SPDX-License-Identifier: GPL-2.0
 2/* Copyright (c) 2025 Meta Platforms, Inc. and affiliates. */
 3
 4#include <vmlinux.h>
 5#include <string.h>
 6#include <stdbool.h>
 7#include <bpf/bpf_helpers.h>
 8#include <bpf/bpf_tracing.h>
 9#include "bpf_misc.h"
10
11char _license[] SEC("license") = "GPL";
12
13const void *user_ptr = NULL;
14
15struct elem {
16	char data[128];
17	struct bpf_task_work tw;
18};
19
20struct {
21	__uint(type, BPF_MAP_TYPE_HASH);
22	__uint(map_flags, BPF_F_NO_PREALLOC);
23	__uint(max_entries, 1);
24	__type(key, int);
25	__type(value, struct elem);
26} hmap SEC(".maps");
27
28struct {
29	__uint(type, BPF_MAP_TYPE_ARRAY);
30	__uint(max_entries, 1);
31	__type(key, int);
32	__type(value, struct elem);
33} arrmap SEC(".maps");
34
35static int process_work(struct bpf_map *map, void *key, void *value)
36{
37	struct elem *work = value;
38
39	bpf_copy_from_user_str(work->data, sizeof(work->data), (const void *)user_ptr, 0);
40	return 0;
41}
42
43int key = 0;
44
45SEC("perf_event")
46__failure __msg("doesn't match map pointer in R3")
47int mismatch_map(struct pt_regs *args)
48{
49	struct elem *work;
50	struct task_struct *task;
51
52	task = bpf_get_current_task_btf();
53	work = bpf_map_lookup_elem(&arrmap, &key);
54	if (!work)
55		return 0;
56	bpf_task_work_schedule_resume_impl(task, &work->tw, &hmap, process_work, NULL);
57	return 0;
58}
59
60SEC("perf_event")
61__failure __msg("arg#1 doesn't point to a map value")
62int no_map_task_work(struct pt_regs *args)
63{
64	struct task_struct *task;
65	struct bpf_task_work tw;
66
67	task = bpf_get_current_task_btf();
68	bpf_task_work_schedule_resume_impl(task, &tw, &hmap, process_work, NULL);
69	return 0;
70}
71
72SEC("perf_event")
73__failure __msg("Possibly NULL pointer passed to trusted arg1")
74int task_work_null(struct pt_regs *args)
75{
76	struct task_struct *task;
77
78	task = bpf_get_current_task_btf();
79	bpf_task_work_schedule_resume_impl(task, NULL, &hmap, process_work, NULL);
80	return 0;
81}
82
83SEC("perf_event")
84__failure __msg("Possibly NULL pointer passed to trusted arg2")
85int map_null(struct pt_regs *args)
86{
87	struct elem *work;
88	struct task_struct *task;
89
90	task = bpf_get_current_task_btf();
91	work = bpf_map_lookup_elem(&arrmap, &key);
92	if (!work)
93		return 0;
94	bpf_task_work_schedule_resume_impl(task, &work->tw, NULL, process_work, NULL);
95	return 0;
96}