[PATCH 3.5 21/60] timekeeping: fix 32-bit overflow in get_monotonic_boottime

[Luis Henriques]

3.5.7.31 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Colin Cross <ccross at android.com>

get_monotonic_boottime adds three nanonsecond values stored
in longs, followed by an s64.  If the long values are all
close to 1e9 the first three additions can overflow and
become negative when added to the s64.  Cast the first
value to s64 so that all additions are 64 bit.

Signed-off-by: Colin Cross <ccross at android.com>
[jstultz: Fished this out of the AOSP commong.git tree. This was
fixed upstream in v3.6 by ec145babe754f9ea1079034a108104b6001e001c]
Signed-off-by: John Stultz <john.stultz at linaro.org>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 kernel/time/timekeeping.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index a9ae4bd..3988562 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -1196,7 +1196,7 @@ void get_monotonic_boottime(struct timespec *ts)
 	} while (read_seqretry(&timekeeper.lock, seq));
 
 	set_normalized_timespec(ts, ts->tv_sec + tomono.tv_sec + sleep.tv_sec,
-			ts->tv_nsec + tomono.tv_nsec + sleep.tv_nsec + nsecs);
+		(s64)ts->tv_nsec + tomono.tv_nsec + sleep.tv_nsec + nsecs);
 }
 EXPORT_SYMBOL_GPL(get_monotonic_boottime);
 
-- 
1.9.0