From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753240AbaHTMDK (ORCPT ); Wed, 20 Aug 2014 08:03:10 -0400 Received: from ip4-83-240-18-248.cust.nbox.cz ([83.240.18.248]:58945 "EHLO ip4-83-240-18-248.cust.nbox.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752550AbaHTLoK (ORCPT ); Wed, 20 Aug 2014 07:44:10 -0400 From: Jiri Slaby To: stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Christoph Paasch , Stephen Hemminger , Neal Cardwell , Eric Dumazet , David Laight , Doug Leith , "David S. Miller" , Jiri Slaby Subject: [PATCH 3.12 037/104] tcp: Fix integer-overflow in TCP vegas Date: Wed, 20 Aug 2014 13:43:00 +0200 Message-Id: <3ef99737f145fce80734b1e868b77422676489d7.1408535000.git.jslaby@suse.cz> X-Mailer: git-send-email 2.0.4 In-Reply-To: References: In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Christoph Paasch 3.12-stable review patch. If anyone has any objections, please let me know. =============== [ 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: Jiri Slaby --- net/ipv4/tcp_vegas.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/net/ipv4/tcp_vegas.c b/net/ipv4/tcp_vegas.c index 80fa2bfd7ede..c042e529a11e 100644 --- a/net/ipv4/tcp_vegas.c +++ b/net/ipv4/tcp_vegas.c @@ -218,7 +218,8 @@ static void tcp_vegas_cong_avoid(struct sock *sk, u32 ack, u32 in_flight) * 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 -- 2.0.4