This is a note to let you know that I've just added the patch titled
bpf: Send signals asynchronously if !preemptible
to the 6.12-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
bpf-send-signals-asynchronously-if-preemptible.patch
and it can be found in the queue-6.12 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit b19ac38b7d19dec9016146515f4b9a0c8f047554
Author: Puranjay Mohan <puranjay@xxxxxxxxxx>
Date: Wed Jan 15 10:36:47 2025 +0000
bpf: Send signals asynchronously if !preemptible
[ Upstream commit 87c544108b612512b254c8f79aa5c0a8546e2cc4 ]
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: syzbot+97da3d7e0112d59971de@xxxxxxxxxxxxxxxxxxxxxxxxx
Closes: https://lore.kernel.org/all/67486b09.050a0220.253251.0084.GAE@xxxxxxxxxx/
Fixes: 1bc7896e9ef4 ("bpf: Fix deadlock with rq_lock in bpf_send_signal()")
Signed-off-by: Puranjay Mohan <puranjay@xxxxxxxxxx>
Acked-by: Yonghong Song <yonghong.song@xxxxxxxxx>
Link: https://lore.kernel.org/r/20250115103647.38487-1-puranjay@xxxxxxxxxx
Signed-off-by: Alexei Starovoitov <ast@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index b5cf605fb0e60..449efaaa387a6 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -833,7 +833,7 @@ static int bpf_send_signal_common(u32 sig, enum pid_type type)
if (unlikely(is_global_init(current)))
return -EPERM;
- if (irqs_disabled()) {
+ if (!preemptible()) {
/* Do an early check on signal validity. Otherwise,
* the error is lost in deferred irq_work.
*/
