From 3da6bb419750f3ad834786d6ba7c9d5d062c770b Mon Sep 17 00:00:00 2001 From: Tetsuo Handa Date: Wed, 9 Jul 2025 20:27:52 +0900 Subject: [PATCH] perf/core: Fix WARN in perf_sigtrap() Since exit_task_work() runs after perf_event_exit_task_context() updated ctx->task to TASK_TOMBSTONE, perf_sigtrap() from perf_pending_task() might observe event->ctx->task == TASK_TOMBSTONE. Swap the early exit tests in order not to hit WARN_ON_ONCE(). Closes: https://syzkaller.appspot.com/bug?extid=2fe61cb2a86066be6985 Reported-by: syzbot Signed-off-by: Tetsuo Handa Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/b1c224bd-97f9-462c-a3e3-125d5e19c983@I-love.SAKURA.ne.jp --- kernel/events/core.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) diff --git a/kernel/events/core.c b/kernel/events/core.c index 0db36b2b2448..22fdf0c187cd 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -7203,6 +7203,13 @@ void perf_event_wakeup(struct perf_event *event) static void perf_sigtrap(struct perf_event *event) { + /* + * Both perf_pending_task() and perf_pending_irq() can race with the + * task exiting. + */ + if (current->flags & PF_EXITING) + return; + /* * We'd expect this to only occur if the irq_work is delayed and either * ctx->task or current has changed in the meantime. This can be the @@ -7211,13 +7218,6 @@ static void perf_sigtrap(struct perf_event *event) if (WARN_ON_ONCE(event->ctx->task != current)) return; - /* - * Both perf_pending_task() and perf_pending_irq() can race with the - * task exiting. - */ - if (current->flags & PF_EXITING) - return; - send_sig_perf((void __user *)event->pending_addr, event->orig_type, event->attr.sig_data); }