Re: [patch 1/8] signal: Prevent exec() race

[Thomas Gleixner]

On Fri, Sep 04 2026 at 13:35, Oleg Nesterov wrote:
> Thomas, I can't read this series today, will try on Weekend.
>
> But you didn't reply to
> https://lore.kernel.org/all/apgHJj0qH7HlAXKO@xxxxxxxxxx/
> Let me quote that email here:
>
> 	OK... lets suppose the exiting task T passes exit_signals().
>
> 	Suppose we have an "ignored" timer tmr. Another sub-thread calls
> 	do_sigaction() -> posixtimer_sig_unignore() and finds that tmr
> 	in ->ignored_posix_timers list.
>
> 	But posixtimer_queue_sigqueue() doesn't check PF_EXITING, I guess
> 	it should check it too?

>From the patch:

@@ -1990,6 +2004,9 @@ void posixtimer_send_sigqueue(struct k_i
	if (!likely(lock_task_sighand(t, &flags)))
		return;

+	if (unlikely(tmr->it_pid_type == PIDTYPE_PID && (t->flags & PF_EXITING)))
+		goto unlock;
+

> 	Or perhaps it makes more sense to check PF_EXITING in
> 	posixtimer_get_target() ?

No. Because that's outside of the sighand locked region and therefore
can't provide a reliable answer.

Thanks,

        tglx