Commit-ID: 10632008b9e18b76cbff0ffc69c15e948aa548e0
Gitweb: http://git.kernel.org/tip/10632008b9e18b76cbff0ffc69c15e948aa548e0
Author: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
AuthorDate: Mon, 20 Oct 2014 15:07:50 +0400
Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitDate: Sat, 25 Oct 2014 10:43:15 +0200
clockevents: Prevent shift out of bounds
Andrey reported that on a kernel with UBSan enabled he found:
UBSan: Undefined behaviour in ../kernel/time/clockevents.c:75:34
I guess it should be 1ULL here instead of 1U:
(!ismax || evt->mult <= (1U << evt->shift)))
That's indeed the correct solution because shift might be 32.
Reported-by: Andrey Ryabinin <a.ryabinin@xxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
---
kernel/time/clockevents.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/time/clockevents.c b/kernel/time/clockevents.c
index 9c94c19..5544990 100644
--- a/kernel/time/clockevents.c
+++ b/kernel/time/clockevents.c
@@ -72,7 +72,7 @@ static u64 cev_delta2ns(unsigned long latch, struct clock_event_device *evt,
* Also omit the add if it would overflow the u64 boundary.
*/
if ((~0ULL - clc > rnd) &&
- (!ismax || evt->mult <= (1U << evt->shift)))
+ (!ismax || evt->mult <= (1ULL << evt->shift)))
clc += rnd;
do_div(clc, evt->mult);
--
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