From: Puranjay Mohan Date: Wed, 15 Jan 2025 10:36:47 +0000 (+0000) Subject: bpf: Send signals asynchronously if !preemptible X-Git-Tag: v5.15.179~523 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=e306eaaa3d78b462db5f5b11e0171f9d2b6ca3f4;p=thirdparty%2Fkernel%2Fstable.git 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@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 Acked-by: Yonghong Song Link: https://lore.kernel.org/r/20250115103647.38487-1-puranjay@kernel.org Signed-off-by: Alexei Starovoitov Signed-off-by: Sasha Levin --- diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index 126754b61edc0..60acc3c76316f 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -799,7 +799,7 @@ 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. */