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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 <error27@gmail.com>
LKML-Reference: <alpine.DEB.2.00.0907191545580.12306@bicker>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Thomas Gleixner 2009-07-19 17:09:12 +02:00
parent 4841158b26
commit 79ef2bb014
1 changed files with 1 additions and 1 deletions
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2
kernel/time/clocksource.c
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@ -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);