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bpf: Check rcu_read_lock_trace_held() in bpf_map_lookup_percpu_elem()

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[ Upstream commit d496557826 ]

bpf_map_lookup_percpu_elem() helper is also available for sleepable bpf
program. When BPF JIT is disabled or under 32-bit host,
bpf_map_lookup_percpu_elem() will not be inlined. Using it in a
sleepable bpf program will trigger the warning in
bpf_map_lookup_percpu_elem(), because the bpf program only holds
rcu_read_lock_trace lock. Therefore, add the missed check.

Reported-by: syzbot+dce5aae19ae4d6399986@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/bpf/000000000000176a130617420310@google.com/
Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20250526062534.1105938-1-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Hou Tao 2025-05-26 14:25:34 +08:00 committed by Greg Kroah-Hartman
parent 61fc32485d
commit 7bf4461f1c
1 changed files with 2 additions and 1 deletions
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3
kernel/bpf/helpers.c
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@ -128,7 +128,8 @@ const struct bpf_func_proto bpf_map_peek_elem_proto = {
BPF_CALL_3(bpf_map_lookup_percpu_elem, struct bpf_map *, map, void *, key, u32, cpu)
{
WARN_ON_ONCE(!rcu_read_lock_held() && !rcu_read_lock_bh_held());
WARN_ON_ONCE(!rcu_read_lock_held() && !rcu_read_lock_trace_held() &&
!rcu_read_lock_bh_held());
return (unsigned long) map->ops->map_lookup_percpu_elem(map, key, cpu);
}