From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756037Ab1B1Qrc (ORCPT ); Mon, 28 Feb 2011 11:47:32 -0500 Received: from kroah.org ([198.145.64.141]:48045 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755439Ab1B1Qha (ORCPT ); Mon, 28 Feb 2011 11:37:30 -0500 X-Mailbox-Line: From gregkh@clark.kroah.org Mon Feb 28 08:24:08 2011 Message-Id: <20110228162408.739075106@clark.kroah.org> User-Agent: quilt/0.48-11.2 Date: Mon, 28 Feb 2011 08:22:51 -0800 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: stable-review@kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, "David S. Miller" , Moritz Muehlenhoff Subject: [30/68] tcp: Increase TCP_MAXSEG socket option minimum. In-Reply-To: <20110228163502.GA27221@kroah.com> 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 us know. ------------------ From: David S. Miller commit 7a1abd08d52fdeddb3e9a5a33f2f15cc6a5674d2 upstream. As noted by Steve Chen, since commit f5fff5dc8a7a3f395b0525c02ba92c95d42b7390 ("tcp: advertise MSS requested by user") we can end up with a situation where tcp_select_initial_window() does a divide by a zero (or even negative) mss value. The problem is that sometimes we effectively subtract TCPOLEN_TSTAMP_ALIGNED and/or TCPOLEN_MD5SIG_ALIGNED from the mss. Fix this by increasing the minimum from 8 to 64. Reported-by: Steve Chen Signed-off-by: David S. Miller Cc: Moritz Muehlenhoff Signed-off-by: Greg Kroah-Hartman --- net/ipv4/tcp.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -2117,7 +2117,7 @@ static int do_tcp_setsockopt(struct sock /* Values greater than interface MTU won't take effect. However * at the point when this call is done we typically don't yet * know which interface is going to be used */ - if (val < 8 || val > MAX_TCP_WINDOW) { + if (val < 64 || val > MAX_TCP_WINDOW) { err = -EINVAL; break; }