alarmtimers: Avoid possible null pointer traversal

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

CC: Thomas Gleixner <tglx@linutronix.de>
CC: stable@kernel.org
Signed-off-by: John Stultz <john.stultz@linaro.org>

1 files changed, 2 insertions, 5 deletions

diff --git a/kernel/time/alarmtimer.c b/kernel/time/alarmtimer.c
index 59f369f98a04..1dee3f62a6a7 100644
--- a/kernel/time/alarmtimer.c
+++ b/kernel/time/alarmtimer.c
@@ -479,11 +479,8 @@ static int alarm_timer_set(struct k_itimer *timr, int flags,
         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);