[PATCH 3.10 50/56] alarmtimer: Fix bug where relative alarm timers were treated as absolute

Greg Kroah-Hartman
2014-07-26T19:02:43Z

From: John Stultz <john.stultz@linaro.org>

commit 16927776ae757d0d132bdbfabbfe2c498342bd59 upstream.

Sharvil noticed with the posix timer_settime interface, using the
CLOCK_REALTIME_ALARM or CLOCK_BOOTTIME_ALARM clockid, if the users
tried to specify a relative time timer, it would incorrectly be
treated as absolute regardless of the state of the flags argument.

This patch corrects this, properly checking the absolute/relative flag,
as well as adds further error checking that no invalid flag bits are set.

Reported-by: Sharvil Nanavati <sharvil@google.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Sharvil Nanavati <sharvil@google.com>
Link: http://lkml.kernel.org/r/1404767171-6902-1-git-send-email-john.stultz@linaro.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
kernel/time/alarmtimer.c | 20 ++++++++++++++++++--
1 file changed, 18 insertions(+), 2 deletions(-)

--- a/kernel/time/alarmtimer.c
+++ b/kernel/time/alarmtimer.c
@@ -540,9 +540,14 @@ static int alarm_timer_set(struct k_itim
struct itimerspec *new_setting,
struct itimerspec *old_setting)
{
+ ktime_t exp;
+
if (!rtcdev)
return -ENOTSUPP;

+ if (flags & ~TIMER_ABSTIME)
+ return -EINVAL;
+
if (old_setting)
alarm_timer_get(timr, old_setting);

@@ -552,8 +557,16 @@ static int alarm_timer_set(struct k_itim

/* start the timer */
timr->it.alarm.interval = timespec_to_ktime(new_setting->it_interval);
- alarm_start(&timr->it.alarm.alarmtimer,
- timespec_to_ktime(new_setting->it_value));
+ exp = timespec_to_ktime(new_setting->it_value);
+ /* Convert (if necessary) to absolute time */
+ if (flags != TIMER_ABSTIME) {
+ ktime_t now;
+
+ now = alarm_bases[timr->it.alarm.alarmtimer.type].gettime();
+ exp = ktime_add(now, exp);
+ }
+
+ alarm_start(&timr->it.alarm.alarmtimer, exp);
return 0;
}

@@ -685,6 +698,9 @@ static int alarm_timer_nsleep(const cloc
if (!alarmtimer_get_rtcdev())
return -ENOTSUPP;

+ if (flags & ~TIMER_ABSTIME)
+ return -EINVAL;
+
if (!capable(CAP_WAKE_ALARM))
return -EPERM;