* potential null dereference in sysfs_override_clocksource()
@ 2009-07-19 13:04 Dan Carpenter
2009-07-19 15:12 ` Thomas Gleixner
2009-07-19 15:19 ` [tip:timers/urgent] clocksource: Prevent NULL pointer dereference tip-bot for Thomas Gleixner
0 siblings, 2 replies; 3+ messages in thread
From: Dan Carpenter @ 2009-07-19 13:04 UTC (permalink / raw)
To: linux-kernel
Hello,
I am testing a source checker (http://repo.or.cz/w/smatch.git).
It found an issue in sysfs_override_clocksource() from
kernel/time/clocksource.c. If "len" is zero then "ovr" is null and
checking ovr->flags will oops on line 517.
kernel/time/clocksource.c
516 if (tick_oneshot_mode_active() &&
517 !(ovr->flags & CLOCK_SOURCE_VALID_FOR_HRES)) {
518 printk(KERN_WARNING "%s clocksource is not HRT compatible. "
regards,
dan carpenter
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: potential null dereference in sysfs_override_clocksource()
2009-07-19 13:04 potential null dereference in sysfs_override_clocksource() Dan Carpenter
@ 2009-07-19 15:12 ` Thomas Gleixner
2009-07-19 15:19 ` [tip:timers/urgent] clocksource: Prevent NULL pointer dereference tip-bot for Thomas Gleixner
1 sibling, 0 replies; 3+ messages in thread
From: Thomas Gleixner @ 2009-07-19 15:12 UTC (permalink / raw)
To: Dan Carpenter; +Cc: LKML, John Stultz
Dan,
On Sun, 19 Jul 2009, Dan Carpenter wrote:
> Hello,
>
> I am testing a source checker (http://repo.or.cz/w/smatch.git).
>
> It found an issue in sysfs_override_clocksource() from
> kernel/time/clocksource.c. If "len" is zero then "ovr" is null and
> checking ovr->flags will oops on line 517.
>
> kernel/time/clocksource.c
> 516 if (tick_oneshot_mode_active() &&
> 517 !(ovr->flags & CLOCK_SOURCE_VALID_FOR_HRES)) {
> 518 printk(KERN_WARNING "%s clocksource is not HRT compatible. "
Indeed. I queued a fix.
Thanks for pointing it out,
tglx
^ permalink raw reply [flat|nested] 3+ messages in thread
* [tip:timers/urgent] clocksource: Prevent NULL pointer dereference
2009-07-19 13:04 potential null dereference in sysfs_override_clocksource() Dan Carpenter
2009-07-19 15:12 ` Thomas Gleixner
@ 2009-07-19 15:19 ` tip-bot for Thomas Gleixner
1 sibling, 0 replies; 3+ messages in thread
From: tip-bot for Thomas Gleixner @ 2009-07-19 15:19 UTC (permalink / raw)
To: linux-tip-commits; +Cc: linux-kernel, hpa, mingo, error27, tglx
Commit-ID: 79ef2bb01445400def20c7993b27fbcad27ca95f
Gitweb: http://git.kernel.org/tip/79ef2bb01445400def20c7993b27fbcad27ca95f
Author: Thomas Gleixner <tglx@linutronix.de>
AuthorDate: Sun, 19 Jul 2009 17:09:12 +0200
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitDate: Sun, 19 Jul 2009 17:15:54 +0200
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>
---
kernel/time/clocksource.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c
index 592bf58..7466cb8 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);
^ permalink raw reply related [flat|nested] 3+ messages in thread
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2009-07-19 13:04 potential null dereference in sysfs_override_clocksource() Dan Carpenter
2009-07-19 15:12 ` Thomas Gleixner
2009-07-19 15:19 ` [tip:timers/urgent] clocksource: Prevent NULL pointer dereference tip-bot for Thomas Gleixner
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