From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751743AbaKPWAz (ORCPT ); Sun, 16 Nov 2014 17:00:55 -0500 Received: from 1wt.eu ([62.212.114.60]:47928 "EHLO 1wt.eu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750938AbaKPWAy (ORCPT ); Sun, 16 Nov 2014 17:00:54 -0500 Message-Id: <20141116215329.653149999@1wt.eu> User-Agent: quilt/0.48-1 Date: Sun, 16 Nov 2014 22:53:52 +0100 From: Willy Tarreau To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Stephen Hemminger , Neal Cardwell , Eric Dumazet , David Laight , Doug Leith , Christoph Paasch , "David S. Miller" , Willy Tarreau Subject: [ 24/48] tcp: Fix integer-overflow in TCP vegas In-Reply-To: <28c765bc23bd4bae1611534e510f49f8@local> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2.6.32-longterm 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: Willy Tarreau --- 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 c6743ee..3044e40 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 -- 1.7.12.2.21.g234cd45.dirty