From owner-freebsd-bugs@FreeBSD.ORG Sat Jan 15 01:40:08 2011 Return-Path: Delivered-To: freebsd-bugs@hub.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 2A1481065670 for ; Sat, 15 Jan 2011 01:40:08 +0000 (UTC) (envelope-from gnats@FreeBSD.org) Received: from freefall.freebsd.org (freefall.freebsd.org [IPv6:2001:4f8:fff6::28]) by mx1.freebsd.org (Postfix) with ESMTP id E62B98FC0C for ; Sat, 15 Jan 2011 01:40:07 +0000 (UTC) Received: from freefall.freebsd.org (localhost [127.0.0.1]) by freefall.freebsd.org (8.14.4/8.14.4) with ESMTP id p0F1e7oE049572 for ; Sat, 15 Jan 2011 01:40:07 GMT (envelope-from gnats@freefall.freebsd.org) Received: (from gnats@localhost) by freefall.freebsd.org (8.14.4/8.14.4/Submit) id p0F1e7j2049571; Sat, 15 Jan 2011 01:40:07 GMT (envelope-from gnats) Resent-Date: Sat, 15 Jan 2011 01:40:07 GMT Resent-Message-Id: <201101150140.p0F1e7j2049571@freefall.freebsd.org> Resent-From: FreeBSD-gnats-submit@FreeBSD.org (GNATS Filer) Resent-To: freebsd-bugs@FreeBSD.org Resent-Reply-To: FreeBSD-gnats-submit@FreeBSD.org, Stefan `Sec` Zehl Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id E1C6A106564A for ; Sat, 15 Jan 2011 01:33:37 +0000 (UTC) (envelope-from sec@42.org) Received: from ice.42.org (v6.42.org [IPv6:2001:608:9::1]) by mx1.freebsd.org (Postfix) with ESMTP id 9CDC98FC08 for ; Sat, 15 Jan 2011 01:33:37 +0000 (UTC) Received: by ice.42.org (Postfix, from userid 1000) id A314E2845B; Sat, 15 Jan 2011 02:33:36 +0100 (CET) Message-Id: <20110115013336.A314E2845B@ice.42.org> Date: Sat, 15 Jan 2011 02:33:36 +0100 (CET) From: Stefan `Sec` Zehl To: FreeBSD-gnats-submit@FreeBSD.org X-Send-Pr-Version: 3.113 Cc: Subject: kern/154006: tcp "window probe" bug on 64bit X-BeenThere: freebsd-bugs@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: Stefan `Sec` Zehl List-Id: Bug reports List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 15 Jan 2011 01:40:08 -0000 >Number: 154006 >Category: kern >Synopsis: tcp "window probe" bug on 64bit >Confidential: no >Severity: non-critical >Priority: low >Responsible: freebsd-bugs >State: open >Quarter: >Keywords: >Date-Required: >Class: sw-bug >Submitter-Id: current-users >Arrival-Date: Sat Jan 15 01:40:07 UTC 2011 >Closed-Date: >Last-Modified: >Originator: Stefan `Sec` Zehl >Release: FreeBSD 8.1-STABLE amd64 >Organization: >Environment: System: FreeBSD ice 8.1-STABLE FreeBSD 8.1-STABLE #15: Mon Oct 25 12:20:38 CEST 2010 root@ice:/usr/obj/usr/src/sys/ICE amd64 As far as I can tell, the offending code is in all FreeBSD versions, not just 8-STABLE >Description: On amd64 the PERSIST timer does not get started (and consecquently executed) for tcp connections stalled on a 0-size receive window. This means that no single-byte probe packet is sent, so connections might hang indefinitely. This is due to a missing (long) conversion in tcp_output.c around line 562 where "adv" is calculated. After this patch, amd64 behaves the same way as i386 again. >How-To-Repeat: connect to a certain broken host which advertises window size 0 in the SYN|ACK handshake packet, but increases window size after the 3-way handshake >Fix: --- src/sys/netinet/tcp_output.c 2010-09-20 17:49:17.000000000 +0200 +++ src/sys/netinet/tcp_output.c 2011-01-14 19:30:46.000000000 +0100 @@ -571,7 +559,7 @@ * TCP_MAXWIN << tp->rcv_scale. */ long adv = min(recwin, (long)TCP_MAXWIN << tp->rcv_scale) - - (tp->rcv_adv - tp->rcv_nxt); + (long) (tp->rcv_adv - tp->rcv_nxt); if (adv >= (long) (2 * tp->t_maxseg)) goto send; >Release-Note: >Audit-Trail: >Unformatted: