From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964994AbcATWKP (ORCPT ); Wed, 20 Jan 2016 17:10:15 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:40231 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S935024AbcATWBh (ORCPT ); Wed, 20 Jan 2016 17:01:37 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Eric Dumazet , Dmitry Vyukov , "David S. Miller" Subject: [PATCH 3.14 11/47] tcp: initialize tp->copied_seq in case of cross SYN connection Date: Wed, 20 Jan 2016 14:00:43 -0800 Message-Id: <20160120215509.287885072@linuxfoundation.org> X-Mailer: git-send-email 2.7.0 In-Reply-To: <20160120215507.575738941@linuxfoundation.org> References: <20160120215507.575738941@linuxfoundation.org> User-Agent: quilt/0.64 MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: Eric Dumazet [ Upstream commit 142a2e7ece8d8ac0e818eb2c91f99ca894730e2a ] Dmitry provided a syzkaller (http://github.com/google/syzkaller) generated program that triggers the WARNING at net/ipv4/tcp.c:1729 in tcp_recvmsg() : WARN_ON(tp->copied_seq != tp->rcv_nxt && !(flags & (MSG_PEEK | MSG_TRUNC))); His program is specifically attempting a Cross SYN TCP exchange, that we support (for the pleasure of hackers ?), but it looks we lack proper tcp->copied_seq initialization. Thanks again Dmitry for your report and testings. Signed-off-by: Eric Dumazet Reported-by: Dmitry Vyukov Tested-by: Dmitry Vyukov Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/ipv4/tcp_input.c | 1 + 1 file changed, 1 insertion(+) --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -5577,6 +5577,7 @@ discard: } tp->rcv_nxt = TCP_SKB_CB(skb)->seq + 1; + tp->copied_seq = tp->rcv_nxt; tp->rcv_wup = TCP_SKB_CB(skb)->seq + 1; /* RFC1323: The window in SYN & SYN/ACK segments is