From patchwork Thu Jan 2 09:21:43 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Wen Yang X-Patchwork-Id: 1217039 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming-netdev@ozlabs.org Delivered-To: patchwork-incoming-netdev@ozlabs.org Authentication-Results: ozlabs.org; spf=none (no SPF record) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; helo=vger.kernel.org; envelope-from=netdev-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=none (p=none dis=none) header.from=linux.alibaba.com Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 47pMxZ1Rg5z9sRp for ; Thu, 2 Jan 2020 20:22:10 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727935AbgABJWF (ORCPT ); Thu, 2 Jan 2020 04:22:05 -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_H=C3=B8iland-J=C3=B8rgensen?= Cc: Wen Yang , Kevin Darbyshire-Bryant , =?utf-8?q?Toke_H=C3=B8iland-J=C3=B8rg?= =?utf-8?q?ensen?= , "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 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@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 Acked-by: Toke Høiland-Jørgensen --- 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);