From 13788ccc41ceea5893f9c747c59bc0b28f2416c2 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Fri, 16 Mar 2007 13:38:20 -0800 Subject: [PATCH] [PATCH] hrtimer: prevent overrun DoS in hrtimer_forward() hrtimer_forward() does not check for the possible overflow of timer->expires. This can happen on 64 bit machines with large interval values and results currently in an endless loop in the softirq because the expiry value becomes negative and therefor the timer is expired all the time. Check for this condition and set the expiry value to the max. expiry time in the future. The fix should be applied to stable kernel series as well. Signed-off-by: Thomas Gleixner Acked-by: Ingo Molnar Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/hrtimer.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c index ec4cb9f3e3b7..5e7122d3f46f 100644 --- a/kernel/hrtimer.c +++ b/kernel/hrtimer.c @@ -644,6 +644,12 @@ hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval) orun++; } timer->expires = ktime_add(timer->expires, interval); + /* + * Make sure, that the result did not wrap with a very large + * interval. + */ + if (timer->expires.tv64 < 0) + timer->expires = ktime_set(KTIME_SEC_MAX, 0); return orun; } -- 2.30.2