From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756352AbaIKMwd (ORCPT ); Thu, 11 Sep 2014 08:52:33 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:51588 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755412AbaIKMeG (ORCPT ); Thu, 11 Sep 2014 08:34:06 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "David S. Miller" , "Neal Cardwell" , "Eric Dumazet" , "Doug Leith" , "David Laight" , "Stephen Hemminger" , "Christoph Paasch" Date: Thu, 11 Sep 2014 13:32:13 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 102/131] tcp: Fix integer-overflow in TCP vegas In-Reply-To: X-SA-Exim-Connect-IP: 192.168.4.249 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.2.63-rc1 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: Ben Hutchings --- 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 80fa2bf..c042e52 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