From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752165Ab3KJTmO (ORCPT ); Sun, 10 Nov 2013 14:42:14 -0500 Received: from mail-ea0-f179.google.com ([209.85.215.179]:54234 "EHLO mail-ea0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751801Ab3KJTmF (ORCPT ); Sun, 10 Nov 2013 14:42:05 -0500 From: Michal Nazarewicz To: Ingo Molnar , Peter Zijlstra Cc: linux-kernel@vger.kernel.org, Michal Nazarewicz Subject: [PATCH] sched: fair: avoid integer overflow Date: Sun, 10 Nov 2013 20:42:01 +0100 Message-Id: <1384112521-25177-1-git-send-email-mpn@google.com> X-Mailer: git-send-email 1.8.4.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Michal Nazarewicz sa->runnable_avg_sum is of type u32 but after shifting it by NICE_0_SHIFT bits it is promoted to u64. This of course makes no sense, since the result will never be more then 32-bit long. Casting sa->runnable_avg_sum to u64 before it is shifted, fixes this problem. Signed-off-by: Michal Nazarewicz --- kernel/sched/fair.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index df77c60..50f1e170 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -2153,7 +2153,7 @@ static inline void __update_tg_runnable_avg(struct sched_avg *sa, long contrib; /* The fraction of a cpu used by this cfs_rq */ - contrib = div_u64(sa->runnable_avg_sum << NICE_0_SHIFT, + contrib = div_u64((u64)sa->runnable_avg_sum << NICE_0_SHIFT, sa->runnable_avg_period + 1); contrib -= cfs_rq->tg_runnable_contrib; -- 1.8.3.2