timekeeping: fix 32-bit overflow in get_monotonic_boottime

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.

Change-Id: Ic996d8b6fbef0b72f2d027b0d8ef5259b5c1a540
Signed-off-by: Colin Cross <ccross@android.com>

diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 84d4f8b25f32162688891c49b529108f983a18b9..5f00308a4e9b0a24d09921daf29c0a72b2a2fa4f 100644 (file)
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -1027,7 +1027,7 @@ void get_monotonic_boottime(struct timespec *ts)
        } while (read_seqretry(&xtime_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);