alarmtimers: Avoid possible denial of service with high freq periodic timers
Its possible to jam up the alarm timers by setting very small interval timers, which will cause the alarmtimer subsystem to spend all of its time firing and restarting timers. This can effectivly lock up a box. A deeper fix is needed, closely mimicking the hrtimer code, but for now just cap the interval to 100us to avoid userland hanging the system. CC: Thomas Gleixner <tglx@linutronix.de> CC: stable@kernel.org Signed-off-by: John Stultz <john.stultz@linaro.org>
This commit is contained in:
parent
ea7802f630
commit
6af7e471e5
|
@ -481,6 +481,15 @@ static int alarm_timer_set(struct k_itimer *timr, int flags,
|
||||||
if (!rtcdev)
|
if (!rtcdev)
|
||||||
return -ENOTSUPP;
|
return -ENOTSUPP;
|
||||||
|
|
||||||
|
/*
|
||||||
|
* XXX HACK! Currently we can DOS a system if the interval
|
||||||
|
* period on alarmtimers is too small. Cap the interval here
|
||||||
|
* to 100us and solve this properly in a future patch! -jstultz
|
||||||
|
*/
|
||||||
|
if ((new_setting->it_interval.tv_sec == 0) &&
|
||||||
|
(new_setting->it_interval.tv_nsec < 100000))
|
||||||
|
new_setting->it_interval.tv_nsec = 100000;
|
||||||
|
|
||||||
if (old_setting)
|
if (old_setting)
|
||||||
alarm_timer_get(timr, old_setting);
|
alarm_timer_get(timr, old_setting);
|
||||||
|
|
||||||
|
|
Loading…
Reference in a new issue