[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 <[email protected]> Acked-by: Ingo Molnar <[email protected]> Cc: <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
josf · Mar 17, 2007 · 13788cc · 13788cc
1 parent d8ad7e0
commit 13788cc
Showing 1 changed file with 6 additions and 0 deletions.
diff --git 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;
 }