Commit 87c54410 authored by Puranjay Mohan's avatar Puranjay Mohan Committed by Alexei Starovoitov
Browse files

bpf: Send signals asynchronously if !preemptible 



BPF programs can execute in all kinds of contexts and when a program
running in a non-preemptible context uses the bpf_send_signal() kfunc,
it will cause issues because this kfunc can sleep.
Change `irqs_disabled()` to `!preemptible()`.

Reported-by: default avatar <syzbot+97da3d7e0112d59971de@syzkaller.appspotmail.com>
Closes: https://lore.kernel.org/all/67486b09.050a0220.253251.0084.GAE@google.com/


Fixes: 1bc7896e ("bpf: Fix deadlock with rq_lock in bpf_send_signal()")
Signed-off-by: default avatarPuranjay Mohan <puranjay@kernel.org>
Acked-by: default avatarYonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20250115103647.38487-1-puranjay@kernel.org


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 9fe17b74

kernel/trace/bpf_trace.c

+1 −1
Original line number Diff line number Diff line
@@ -842,7 +842,7 @@ static int bpf_send_signal_common(u32 sig, enum pid_type type, struct task_struc 
	if (unlikely(is_global_init(task)))

		return -EPERM;



	if (irqs_disabled()) {

	if (!preemptible()) {

		/* Do an early check on signal validity. Otherwise,

		 * the error is lost in deferred irq_work.

		 */