From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.toke.dk (mail.toke.dk [45.145.95.4]) (using TLSv1.2 with cipher ADH-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id 53B8F3B29E for ; Thu, 2 Jan 2020 18:34:04 -0500 (EST) From: Toke =?utf-8?Q?H=C3=B8iland-J=C3=B8rgensen?= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=toke.dk; s=20161023; t=1578008042; bh=n+/Z2y8RBVuqOI4GbqxFKUrx0mw1L0vQ5v5oMAmp7p4=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From; b=LoYd6qXDE5xAkgF2bwCD0T2jgTeox5j6DXM1M6YwSyyiIgC4s339InEiSQ+Ii9jEw E/03m4wW582/wfubbb5xghNEIY440TWkImjxPtKQrS6bPV43ssXEJz79HyoCtFA0WK jlfLzgl6Z20tN8ZdeNSgcyZ1/x6xf7f3uIaaVXk3NEZusaBYY0md3LnksEl/c9zV70 i/XJP7w99sQRz/7o9Yh13kZtpl3ESq50+BRdyRlwZ71fN7M7Lk0O8hfCnNSWVjXgxm 47uMNKSNCrYZujafjMO1cDRwfakGV3N9FBOiYwzlyQDfk4vxrFT8wJb2goOueaRRPk /3EEhSnY9xDCg== To: Wen Yang Cc: Wen Yang , Kevin Darbyshire-Bryant , "David S . Miller" , Cong Wang , cake@lists.bufferbloat.net, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] sch_cake: avoid possible divide by zero in cake_enqueue() In-Reply-To: <20200102092143.8971-1-wenyang@linux.alibaba.com> References: <20200102092143.8971-1-wenyang@linux.alibaba.com> Date: Fri, 03 Jan 2020 00:34:01 +0100 X-Clacks-Overhead: GNU Terry Pratchett Message-ID: <87ftgxl9g6.fsf@toke.dk> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-List-Received-Date: Thu, 02 Jan 2020 23:34:04 -0000 Wen Yang writes: > 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 H=C3=B8iland-J=C3=B8rgensen > 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 H=C3=B8iland-J=C3=B8rgensen