From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, UNPARSEABLE_RELAY,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0A816C2D0DC for ; Thu, 2 Jan 2020 09:22:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CC3F620866 for ; Thu, 2 Jan 2020 09:22:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727949AbgABJWG (ORCPT ); Thu, 2 Jan 2020 04:22:06 -0500 Received: from out4436.biz.mail.alibaba.com ([47.88.44.36]:12303 "EHLO out4436.biz.mail.alibaba.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727801AbgABJWF (ORCPT ); Thu, 2 Jan 2020 04:22:05 -0500 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R111e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04395;MF=wenyang@linux.alibaba.com;NM=1;PH=DS;RN=9;SR=0;TI=SMTPD_---0TmbxYO7_1577956905; Received: from localhost(mailfrom:wenyang@linux.alibaba.com fp:SMTPD_---0TmbxYO7_1577956905) by smtp.aliyun-inc.com(127.0.0.1); Thu, 02 Jan 2020 17:21:53 +0800 From: Wen Yang To: =?UTF-8?q?Toke=20H=C3=B8iland-J=C3=B8rgensen?= Cc: Wen Yang , Kevin Darbyshire-Bryant , =?UTF-8?q?Toke=20H=C3=B8iland-J=C3=B8rgensen?= , "David S . Miller" , Cong Wang , cake@lists.bufferbloat.net, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] sch_cake: avoid possible divide by zero in cake_enqueue() Date: Thu, 2 Jan 2020 17:21:43 +0800 Message-Id: <20200102092143.8971-1-wenyang@linux.alibaba.com> X-Mailer: git-send-email 2.23.0 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The variables 'window_interval' is u64 and do_div() truncates it to 32 bits, which means it can test non-zero and be truncated to zero for division. The unit of window_interval is nanoseconds, so its lower 32-bit is relatively easy to exceed. Fix this issue by using div64_u64() instead. Fixes: 7298de9cd725 ("sch_cake: Add ingress mode") Signed-off-by: Wen Yang Cc: Kevin Darbyshire-Bryant Cc: Toke Høiland-Jørgensen Cc: David S. Miller Cc: Cong Wang Cc: cake@lists.bufferbloat.net Cc: netdev@vger.kernel.org Cc: linux-kernel@vger.kernel.org --- net/sched/sch_cake.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/sched/sch_cake.c b/net/sched/sch_cake.c index 6cc3ab1..90ef7cc 100644 --- a/net/sched/sch_cake.c +++ b/net/sched/sch_cake.c @@ -1768,7 +1768,7 @@ static s32 cake_enqueue(struct sk_buff *skb, struct Qdisc *sch, q->avg_window_begin)); u64 b = q->avg_window_bytes * (u64)NSEC_PER_SEC; - do_div(b, window_interval); + b = div64_u64(b, window_interval); q->avg_peak_bandwidth = cake_ewma(q->avg_peak_bandwidth, b, b > q->avg_peak_bandwidth ? 2 : 8); -- 1.8.3.1