5.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Puranjay Mohan puranjay@kernel.org
[ 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@syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/67486b09.050a0220.253251.0084.GAE@google.com/ Fixes: 1bc7896e9ef4 ("bpf: Fix deadlock with rq_lock in bpf_send_signal()") Signed-off-by: Puranjay Mohan puranjay@kernel.org Acked-by: Yonghong Song yonghong.song@linux.dev Link: https://lore.kernel.org/r/20250115103647.38487-1-puranjay@kernel.org Signed-off-by: Alexei Starovoitov ast@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/trace/bpf_trace.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index 4a31763a8c5d7..ac3125d0c73f1 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -653,7 +653,7 @@ BPF_CALL_1(bpf_send_signal, u32, sig) 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. */