[057/244] alarmtimers: Avoid possible null pointer traversal

[Greg KH]

3.0-stable review patch.  If anyone has any objections, please let us know.

------------------

From: John Stultz <john.stultz@xxxxxxxxxx>

commit 971c90bfa2f0b4fe52d6d9002178d547706f1343 upstream.

We don't check if old_setting is non null before assigning it, so
correct this.

CC: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: John Stultz <john.stultz@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
 kernel/time/alarmtimer.c |    7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

--- a/kernel/time/alarmtimer.c
+++ b/kernel/time/alarmtimer.c
@@ -479,11 +479,8 @@ static int alarm_timer_set(struct k_itim
 	if (!rtcdev)
 		return -ENOTSUPP;
 
-	/* Save old values */
-	old_setting->it_interval =
-			ktime_to_timespec(timr->it.alarmtimer.period);
-	old_setting->it_value =
-			ktime_to_timespec(timr->it.alarmtimer.node.expires);
+	if (old_setting)
+		alarm_timer_get(timr, old_setting);
 
 	/* If the timer was already set, cancel it */
 	alarm_cancel(&timr->it.alarmtimer);


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