timers: Fix overflow in get_next_timer_interrupt

For e.g. HZ=100, timer being 430 jiffies in the future, and 32 bit
unsigned int, there is an overflow on unsigned int right-hand side
of the expression which results with wrong values being returned.

Type cast the multiplier to 64bit to avoid that issue.

Fixes: 46c8f0b077a8 ("timers: Fix get_next_timer_interrupt() computation")
Signed-off-by: Matija Glavinic Pecotic <matija.glavinic-pecotic.ext@nokia.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexander Sverdlin <alexander.sverdlin@nokia.com>
Cc: khilman@baylibre.com
Cc: akpm@linux-foundation.org
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/a7900f04-2a21-c9fd-67be-ab334d459ee5@nokia.com

diff --git a/kernel/time/timer.c b/kernel/time/timer.c
index 71ce3f4eead34afc12fa2743c69e8e9e77c544ad..8f5d1bf18854593e6fa27730d07a99c6700ab45c 100644 (file)
--- a/kernel/time/timer.c
+++ b/kernel/time/timer.c
@@ -1495,7 +1495,7 @@ u64 get_next_timer_interrupt(unsigned long basej, u64 basem)
                base->is_idle = false;
        } else {
                if (!is_max_delta)
                base->is_idle = false;
        } else {
                if (!is_max_delta)

-                       expires = basem + (nextevt - basej) * TICK_NSEC;
+                       expires = basem + (u64)(nextevt - basej) * TICK_NSEC;

                /*
                 * If we expect to sleep more than a tick, mark the base idle:
                 */
                /*
                 * If we expect to sleep more than a tick, mark the base idle:
                 */