Merge branch 'timers-fixes-for-linus' of git://tesla.tglx.de/git/linux-2.6-tip

* 'timers-fixes-for-linus' of git://tesla.tglx.de/git/linux-2.6-tip:
  rtc: twl: Fix registration vs. init order
  rtc: Initialized rtc_time->tm_isdst
  rtc: Fix RTC PIE frequency limit
  rtc: rtc-twl: Remove lockdep related local_irq_enable()
  rtc: rtc-twl: Switch to using threaded irq
  rtc: ep93xx: Fix 'rtc' may be used uninitialized warning
  alarmtimers: Avoid possible denial of service with high freq periodic timers
  alarmtimers: Memset itimerspec passed into alarm_timer_get
  alarmtimers: Avoid possible null pointer traversal

1 files changed, 13 insertions, 5 deletions

diff --git a/kernel/time/alarmtimer.c b/kernel/time/alarmtimer.c
index 59f369f98a0..ea5e1a928d5 100644
--- a/kernel/time/alarmtimer.c
+++ b/kernel/time/alarmtimer.c
@@ -441,6 +441,8 @@ static int alarm_timer_create(struct k_itimer *new_timer)
 static void alarm_timer_get(struct k_itimer *timr,
                                 struct itimerspec *cur_setting)
 {
+        memset(cur_setting, 0, sizeof(struct itimerspec));
+
         cur_setting->it_interval =
                         ktime_to_timespec(timr->it.alarmtimer.period);
         cur_setting->it_value =
@@ -479,11 +481,17 @@ 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);
+        /*
+         * XXX HACK! Currently we can DOS a system if the interval
+         * period on alarmtimers is too small. Cap the interval here
+         * to 100us and solve this properly in a future patch! -jstultz
+         */
+        if ((new_setting->it_interval.tv_sec == 0) &&
+                        (new_setting->it_interval.tv_nsec < 100000))
+                new_setting->it_interval.tv_nsec = 100000;
+
+        if (old_setting)
+                alarm_timer_get(timr, old_setting);
 
         /* If the timer was already set, cancel it */
         alarm_cancel(&timr->it.alarmtimer);