From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932391AbbLNMqw (ORCPT ); Mon, 14 Dec 2015 07:46:52 -0500 Received: from mx2.parallels.com ([199.115.105.18]:38512 "EHLO mx2.parallels.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932272AbbLNMqu (ORCPT ); Mon, 14 Dec 2015 07:46:50 -0500 From: Andrey Ryabinin To: , CC: , , , , , , Andrey Ryabinin Subject: [PATCH v2] sched/fair: fix mul overflow on 32-bit systems Date: Mon, 14 Dec 2015 15:47:23 +0300 Message-ID: <1450097243-30137-1-git-send-email-aryabinin@virtuozzo.com> X-Mailer: git-send-email 2.4.10 MIME-Version: 1.0 Content-Type: text/plain X-ClientProxiedBy: US-EXCH.sw.swsoft.com (10.255.249.47) To US-EXCH.sw.swsoft.com (10.255.249.47) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Make 'r' 64-bit type to avoid overflow in 'r * LOAD_AVG_MAX' on 32-bit systems: UBSAN: Undefined behaviour in kernel/sched/fair.c:2785:18 signed integer overflow: 87950 * 47742 cannot be represented in type 'int' Fixes: 9d89c257dfb9 ("sched/fair: Rewrite runnable load and utilization average tracking") Signed-off-by: Andrey Ryabinin --- Changes since v1: - Removed wrong second hunk. Anyway, if fix for util_avg is needed, it deserves a separte patch. 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 90e26b1..cfdc0e6 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -2689,7 +2689,7 @@ static inline int update_cfs_rq_load_avg(u64 now, struct cfs_rq *cfs_rq) int decayed, removed = 0; if (atomic_long_read(&cfs_rq->removed_load_avg)) { - long r = atomic_long_xchg(&cfs_rq->removed_load_avg, 0); + s64 r = atomic_long_xchg(&cfs_rq->removed_load_avg, 0); sa->load_avg = max_t(long, sa->load_avg - r, 0); sa->load_sum = max_t(s64, sa->load_sum - r * LOAD_AVG_MAX, 0); removed = 1; -- 2.4.10