Commit d4965578 authored by Hou Tao's avatar Hou Tao Committed by Alexei Starovoitov
Browse files

bpf: Check rcu_read_lock_trace_held() in bpf_map_lookup_percpu_elem() 



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: default avatar <syzbot+dce5aae19ae4d6399986@syzkaller.appspotmail.com>
Closes: https://lore.kernel.org/bpf/000000000000176a130617420310@google.com/


Signed-off-by: default avatarHou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20250526062534.1105938-1-houtao@huaweicloud.com


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 86bc9c74

kernel/bpf/helpers.c

+2 −1
Original line number Diff line number Diff line
@@ -130,7 +130,8 @@ 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);

}