hrtimer: check relative timeouts for overflow

Various user space callers ask for relative timeouts. While we fixed
that overflow issue in hrtimer_start(), the sites which convert
relative user space values to absolute timeouts themself were uncovered.

Instead of putting overflow checks into each place add a function
which does the sanity checking and convert all affected callers to use
it.

Thanks to Frans Pop, who reported the problem and tested the fixes.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Ingo Molnar <mingo@elte.hu>
Tested-by: Frans Pop <elendil@planet.nl>

1 files changed, 5 insertions, 3 deletions

diff --git a/kernel/posix-timers.c b/kernel/posix-timers.c
index 022c9c3..a9b0420 100644
--- a/kernel/posix-timers.c
+++ b/kernel/posix-timers.c
@@ -767,9 +767,11 @@ common_timer_set(struct k_itimer *timr, int flags,
 	/* SIGEV_NONE timers are not queued ! See common_timer_get */
 	if (((timr->it_sigev_notify & ~SIGEV_THREAD_ID) == SIGEV_NONE)) {
 		/* Setup correct expiry time for relative timers */
-		if (mode == HRTIMER_MODE_REL)
-			timer->expires = ktime_add(timer->expires,
-						   timer->base->get_time());
+		if (mode == HRTIMER_MODE_REL) {
+			timer->expires =
+				ktime_add_safe(timer->expires,
+					       timer->base->get_time());
+		}
 		return 0;
 	}