Messages in this thread Patch in this message | | | Date | Mon, 17 Dec 2018 13:31:05 +0100 (CET) | From | Thomas Gleixner <> | Subject | [PATCH] posix-timers: Prevent division by zero |
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The signal delivery path of posix-timers can try to rearm the timer even if the interval is zero. That's handled for the common case (hrtimer) but not for alarm timers. In that case the forwarding function raises a division by zero exception.
The handling for hrtimer based posix timers is wrong because it marks the timer as active despite the fact that it is stopped.
Move the check from common_hrtimer_rearm() to posixtimer_rearm() to cure both issues.
Reported-by: syzbot+9d38bedac9cc77b8ad5e@syzkaller.appspotmail.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: stable@vger.kernel.org --- kernel/time/posix-timers.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-)
--- a/kernel/time/posix-timers.c +++ b/kernel/time/posix-timers.c @@ -289,9 +289,6 @@ static void common_hrtimer_rearm(struct { struct hrtimer *timer = &timr->it.real.timer; - if (!timr->it_interval) - return; - timr->it_overrun += hrtimer_forward(timer, timer->base->get_time(), timr->it_interval); hrtimer_restart(timer); @@ -317,7 +314,7 @@ void posixtimer_rearm(struct kernel_sigi if (!timr) return; - if (timr->it_requeue_pending == info->si_sys_private) { + if (timr->it_interval && timr->it_requeue_pending == info->si_sys_private) { timr->kclock->timer_rearm(timr); timr->it_active = 1;
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