29 Mar
2021
29 Mar
'21
2:27 p.m.
On 03/29, Peter Zijlstra wrote:
On Thu, Mar 25, 2021 at 09:14:39AM +0100, Marco Elver wrote:
@@ -6395,6 +6395,13 @@ static void perf_sigtrap(struct perf_event *event) { struct kernel_siginfo info;
- /*
* This irq_work can race with an exiting task; bail out if sighand has* already been released in release_task().*/- if (!current->sighand)
return;
This is racy. If "current" has already passed exit_notify(), current->parent can do release_task() and destroy current->sighand right after the check.
Urgh.. I'm not entirely sure that check is correct, but I always forget the rules with signal. It could be we ought to be testing PF_EXISTING instead.
Agreed, PF_EXISTING check makes more sense in any case, the exiting task can't receive the signal anyway.
Oleg.