rtc: limit frequency

Due to the hrtimer self rearming mode a user can DoS the machine simply
because it's starved by hrtimer events.

The RTC hrtimer is self rearming.  We really need to limit the frequency
to something sensible.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Ben Greear <greearb@candelatech.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Thomas Gleixner 2011-07-26 16:08:19 -07:00 committed by Linus Torvalds
parent 2c4f57d12d
commit 431e2bcc37

View File

@ -688,7 +688,7 @@ int rtc_irq_set_freq(struct rtc_device *rtc, struct rtc_task *task, int freq)
int err = 0;
unsigned long flags;
if (freq <= 0)
if (freq <= 0 || freq > 5000)
return -EINVAL;
spin_lock_irqsave(&rtc->irq_task_lock, flags);