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authorLinus Torvalds <torvalds@linux-foundation.org>2011-09-07 13:03:48 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2011-09-07 13:03:48 -0700
commit79016f648872549392d232cd648bd02298c2d2bb (patch)
tree8b3f435b7ff3633b0a82313a1bb12d052f36c6b7 /kernel
parente81b693c0104d6a767f998ee5a2e00b5acbbcd18 (diff)
parent486257130873a2172d8eac2c182f7e578465bdd0 (diff)
downloadlinux-linaro-precise-79016f648872549392d232cd648bd02298c2d2bb.tar.gz
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
Diffstat (limited to 'kernel')
-rw-r--r--kernel/time/alarmtimer.c18
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);