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authorThomas Gleixner <tglx@linutronix.de>2018-12-17 13:31:05 +0100
committerIngo Molnar <mingo@kernel.org>2018-12-17 17:35:45 +0100
commit0e334db6bb4b1fd1e2d72c1f3d8f004313cd9f94 (patch)
treee10400116050673c0667f7cac51f4aed72ea27f6 /kernel/time
parent7566ec393f4161572ba6f11ad5171fd5d59b0fbd (diff)
posix-timers: Fix division by zero bug
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: John Stultz <john.stultz@linaro.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: sboyd@kernel.org Cc: stable@vger.kernel.org Cc: syzkaller-bugs@googlegroups.com Link: http://lkml.kernel.org/r/alpine.DEB.2.21.1812171328050.1880@nanos.tec.linutronix.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/time')
-rw-r--r--kernel/time/posix-timers.c5
1 files changed, 1 insertions, 4 deletions
diff --git a/kernel/time/posix-timers.c b/kernel/time/posix-timers.c
index bd62b5eeb5a0..31f49ae80f43 100644
--- a/kernel/time/posix-timers.c
+++ b/kernel/time/posix-timers.c
@@ -289,9 +289,6 @@ static void common_hrtimer_rearm(struct k_itimer *timr)
{
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_siginfo *info)
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;