diff options
| author | Oleg Nesterov <oleg@tv-sign.ru> | 2005-09-06 15:17:42 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2005-09-07 16:57:33 -0700 |
| commit | e752dd6cc66a3e6a11396928998baf390cc00420 (patch) | |
| tree | b24b388d80acec6527e66b07f0d308d48319c476 /kernel/posix-timers.c | |
| parent | a97c9bf33f4612e2aed6f000f6b1d268b6814f3c (diff) | |
[PATCH] fix send_sigqueue() vs thread exit race
posix_timer_event() first checks that the thread (SIGEV_THREAD_ID case)
does not have PF_EXITING flag, then it calls send_sigqueue() which locks
task list. But if the thread exits in between the kernel will oops
(->sighand == NULL after __exit_sighand).
This patch moves the PF_EXITING check into the send_sigqueue(), it must be
done atomically under tasklist_lock. When send_sigqueue() detects exiting
thread it returns -1. In that case posix_timer_event will send the signal
to thread group.
Also, this patch fixes task_struct use-after-free in posix_timer_event.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'kernel/posix-timers.c')
| -rw-r--r-- | kernel/posix-timers.c | 28 |
1 files changed, 15 insertions, 13 deletions
diff --git a/kernel/posix-timers.c b/kernel/posix-timers.c index 38798a2ff994..b7b532acd9fc 100644 --- a/kernel/posix-timers.c +++ b/kernel/posix-timers.c @@ -427,21 +427,23 @@ int posix_timer_event(struct k_itimer *timr,int si_private) timr->sigq->info.si_code = SI_TIMER; timr->sigq->info.si_tid = timr->it_id; timr->sigq->info.si_value = timr->it_sigev_value; + if (timr->it_sigev_notify & SIGEV_THREAD_ID) { - if (unlikely(timr->it_process->flags & PF_EXITING)) { - timr->it_sigev_notify = SIGEV_SIGNAL; - put_task_struct(timr->it_process); - timr->it_process = timr->it_process->group_leader; - goto group; - } - return send_sigqueue(timr->it_sigev_signo, timr->sigq, - timr->it_process); - } - else { - group: - return send_group_sigqueue(timr->it_sigev_signo, timr->sigq, - timr->it_process); + struct task_struct *leader; + int ret = send_sigqueue(timr->it_sigev_signo, timr->sigq, + timr->it_process); + + if (likely(ret >= 0)) + return ret; + + timr->it_sigev_notify = SIGEV_SIGNAL; + leader = timr->it_process->group_leader; + put_task_struct(timr->it_process); + timr->it_process = leader; } + + return send_group_sigqueue(timr->it_sigev_signo, timr->sigq, + timr->it_process); } EXPORT_SYMBOL_GPL(posix_timer_event); |