From: Puranjay Mohan <puranjay@kernel.org>
To: Song Liu <song@kernel.org>, Jiri Olsa <jolsa@kernel.org>,
KP Singh <kpsingh@kernel.org>,
Matt Bobrowski <mattbobrowski@google.com>,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii@kernel.org>,
Martin KaFai Lau <martin.lau@linux.dev>,
Eduard Zingerman <eddyz87@gmail.com>,
Yonghong Song <yonghong.song@linux.dev>,
John Fastabend <john.fastabend@gmail.com>,
Stanislav Fomichev <sdf@fomichev.me>, Hao Luo <haoluo@google.com>,
Steven Rostedt <rostedt@goodmis.org>,
Masami Hiramatsu <mhiramat@kernel.org>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
bpf@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-trace-kernel@vger.kernel.org, puranjay12@gmail.com
Subject: [PATCH bpf] bpf: trace: send signals asynchronously if !preemptible
Date: Wed, 15 Jan 2025 10:36:47 +0000 [thread overview]
Message-ID: <20250115103647.38487-1-puranjay@kernel.org> (raw)
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.
So change `irqs_disabled()` to `!preemptible()` that covers all edge
cases: preempt_count() == 0 and irqs_disabled()
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>
---
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 1b8db5aee9d3..d162c87e09a8 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -853,7 +853,7 @@ 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.
*/
--
2.40.1
next reply other threads:[~2025-01-15 10:37 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-01-15 10:36 Puranjay Mohan [this message]
2025-01-15 16:55 ` [PATCH bpf] bpf: trace: send signals asynchronously if !preemptible Yonghong Song
2025-01-15 21:50 ` patchwork-bot+netdevbpf
2025-01-21 1:26 ` Hou Tao
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