timekeeping: Cast raw_interval to u64 to avoid shift overflow

commit 5b3900cd upstream.

We fixed a bunch of integer overflows in timekeeping code during the 3.6
cycle.  I did an audit based on that and found this potential overflow.
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: John Stultz <johnstul@us.ibm.com>
Link: http://lkml.kernel.org/r/20121009071823.GA19159@elgon.mountainSigned-off-by: Thomas Gleixner <tglx@linutronix.de>
[bwh: Backported to 3.2: adjust context; use timekeeper.raw_interval]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

kernel/time/timekeeping.c

@@ -992,7 +992,7 @@ static cycle_t logarithmic_accumulation(cycle_t offset, int shift)
 	}
 
 	/* Accumulate raw time */
-	raw_nsecs = timekeeper.raw_interval << shift;
+	raw_nsecs = (u64)timekeeper.raw_interval << shift;
 	raw_nsecs += raw_time.tv_nsec;
 	if (raw_nsecs >= NSEC_PER_SEC) {
 		u64 raw_secs = raw_nsecs;