From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932866AbaHHWO2 (ORCPT ); Fri, 8 Aug 2014 18:14:28 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:60327 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757030AbaHHVfx (ORCPT ); Fri, 8 Aug 2014 17:35:53 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Stephen Hemminger , Neal Cardwell , Eric Dumazet , David Laight , Doug Leith , Christoph Paasch , "David S. Miller" Subject: [PATCH 3.4 05/23] tcp: Fix integer-overflow in TCP vegas Date: Fri, 8 Aug 2014 14:34:50 -0700 Message-Id: <20140808213315.998631140@linuxfoundation.org> X-Mailer: git-send-email 2.0.4 In-Reply-To: <20140808213315.769217722@linuxfoundation.org> References: <20140808213315.769217722@linuxfoundation.org> User-Agent: quilt/0.63-1 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Christoph Paasch [ Upstream commit 1f74e613ded11517db90b2bd57e9464d9e0fb161 ] In vegas we do a multiplication of the cwnd and the rtt. This may overflow and thus their result is stored in a u64. However, we first need to cast the cwnd so that actually 64-bit arithmetic is done. Then, we need to do do_div to allow this to be used on 32-bit arches. Cc: Stephen Hemminger Cc: Neal Cardwell Cc: Eric Dumazet Cc: David Laight Cc: Doug Leith Fixes: 8d3a564da34e (tcp: tcp_vegas cong avoid fix) Signed-off-by: Christoph Paasch Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/ipv4/tcp_vegas.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/net/ipv4/tcp_vegas.c +++ b/net/ipv4/tcp_vegas.c @@ -218,7 +218,8 @@ static void tcp_vegas_cong_avoid(struct * This is: * (actual rate in segments) * baseRTT */ - target_cwnd = tp->snd_cwnd * vegas->baseRTT / rtt; + target_cwnd = (u64)tp->snd_cwnd * vegas->baseRTT; + do_div(target_cwnd, rtt); /* Calculate the difference between the window we had, * and the window we would like to have. This quantity