From 79ef2bb01445400def20c7993b27fbcad27ca95f Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Sun, 19 Jul 2009 17:09:12 +0200 Subject: [PATCH] clocksource: Prevent NULL pointer dereference Writing a zero length string to sys/.../current_clocksource will cause a NULL pointer dereference if the clock events system is in one shot (highres or nohz) mode. Pointed-out-by: Dan Carpenter LKML-Reference: Signed-off-by: Thomas Gleixner --- kernel/time/clocksource.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c index 592bf584d1d2..7466cb811251 100644 --- a/kernel/time/clocksource.c +++ b/kernel/time/clocksource.c @@ -513,7 +513,7 @@ static ssize_t sysfs_override_clocksource(struct sys_device *dev, * Check to make sure we don't switch to a non-highres capable * clocksource if the tick code is in oneshot mode (highres or nohz) */ - if (tick_oneshot_mode_active() && + if (tick_oneshot_mode_active() && ovr && !(ovr->flags & CLOCK_SOURCE_VALID_FOR_HRES)) { printk(KERN_WARNING "%s clocksource is not HRT compatible. " "Cannot switch while in HRT/NOHZ mode\n", ovr->name);