From owner-svn-src-head@FreeBSD.ORG  Wed Mar 30 12:35:40 2011
Return-Path: <owner-svn-src-head@FreeBSD.ORG>
Delivered-To: svn-src-head@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34])
	by hub.freebsd.org (Postfix) with ESMTP id 0C5E6106566B;
	Wed, 30 Mar 2011 12:35:40 +0000 (UTC) (envelope-from jhb@FreeBSD.org)
Received: from svn.freebsd.org (svn.freebsd.org [IPv6:2001:4f8:fff6::2c])
	by mx1.freebsd.org (Postfix) with ESMTP id F16CC8FC08;
	Wed, 30 Mar 2011 12:35:39 +0000 (UTC)
Received: from svn.freebsd.org (localhost [127.0.0.1])
	by svn.freebsd.org (8.14.3/8.14.3) with ESMTP id p2UCZds1063677;
	Wed, 30 Mar 2011 12:35:39 GMT (envelope-from jhb@svn.freebsd.org)
Received: (from jhb@localhost)
	by svn.freebsd.org (8.14.3/8.14.3/Submit) id p2UCZdwP063675;
	Wed, 30 Mar 2011 12:35:39 GMT (envelope-from jhb@svn.freebsd.org)
Message-Id: <201103301235.p2UCZdwP063675@svn.freebsd.org>
From: John Baldwin <jhb@FreeBSD.org>
Date: Wed, 30 Mar 2011 12:35:39 +0000 (UTC)
To: src-committers@freebsd.org, svn-src-all@freebsd.org,
	svn-src-head@freebsd.org
X-SVN-Group: head
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Cc: 
Subject: svn commit: r220156 - head/sys/netinet
X-BeenThere: svn-src-head@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: SVN commit messages for the src tree for head/-current
	<svn-src-head.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/svn-src-head>,
	<mailto:svn-src-head-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/svn-src-head>
List-Post: <mailto:svn-src-head@freebsd.org>
List-Help: <mailto:svn-src-head-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/svn-src-head>,
	<mailto:svn-src-head-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Wed, 30 Mar 2011 12:35:40 -0000

Author: jhb
Date: Wed Mar 30 12:35:39 2011
New Revision: 220156
URL: http://svn.freebsd.org/changeset/base/220156

Log:
  Clamp the initial advertised receive window when responding to a SYN/ACK
  to the maximum allowed window.  Growing the window too large would cause
  an underflow in the calculations in tcp_output() to decide if a window
  update should be sent which would prevent the persist timer from being
  started if data was pending and the other end of the connection advertised
  an initial window size of 0.
  
  PR:		kern/154006
  Submitted by:	Stefan `Sec` Zehl  sec 42 org
  Reviewed by:	bz
  MFC after:	1 week

Modified:
  head/sys/netinet/tcp_input.c

Modified: head/sys/netinet/tcp_input.c
==============================================================================
--- head/sys/netinet/tcp_input.c	Wed Mar 30 11:34:40 2011	(r220155)
+++ head/sys/netinet/tcp_input.c	Wed Mar 30 12:35:39 2011	(r220156)
@@ -1756,7 +1756,8 @@ tcp_do_segment(struct mbuf *m, struct tc
 				(TF_RCVD_SCALE|TF_REQ_SCALE)) {
 				tp->rcv_scale = tp->request_r_scale;
 			}
-			tp->rcv_adv += tp->rcv_wnd;
+			tp->rcv_adv += imin(tp->rcv_wnd,
+			    TCP_MAXWIN << tp->rcv_scale);
 			tp->snd_una++;		/* SYN is acked */
 			/*
 			 * If there's data, delay ACK; if there's also a FIN