From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934337AbdKAVbj (ORCPT ); Wed, 1 Nov 2017 17:31:39 -0400 Received: from wtarreau.pck.nerim.net ([62.212.114.60]:35538 "EHLO 1wt.eu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934572AbdKAVaJ (ORCPT ); Wed, 1 Nov 2017 17:30:09 -0400 From: Willy Tarreau To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, linux@roeck-us.net Cc: Wei Wang , Eric Dumazet , Neal Cardwell , Yuchung Cheng , "David S . Miller" , Willy Tarreau Subject: [PATCH 3.10 084/139] tcp: initialize rcv_mss to TCP_MIN_MSS instead of 0 Date: Wed, 1 Nov 2017 22:26:25 +0100 Message-Id: <1509571600-4858-35-git-send-email-w@1wt.eu> X-Mailer: git-send-email 2.8.0.rc2.1.gbe9624a In-Reply-To: <1509571600-4858-1-git-send-email-w@1wt.eu> References: <1509571159-4405-1-git-send-email-w@1wt.eu> <1509571600-4858-1-git-send-email-w@1wt.eu> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Wei Wang commit 499350a5a6e7512d9ed369ed63a4244b6536f4f8 upstream. When tcp_disconnect() is called, inet_csk_delack_init() sets icsk->icsk_ack.rcv_mss to 0. This could potentially cause tcp_recvmsg() => tcp_cleanup_rbuf() => __tcp_select_window() call path to have division by 0 issue. So this patch initializes rcv_mss to TCP_MIN_MSS instead of 0. Reported-by: Andrey Konovalov Signed-off-by: Wei Wang Signed-off-by: Eric Dumazet Signed-off-by: Neal Cardwell Signed-off-by: Yuchung Cheng Signed-off-by: David S. Miller Signed-off-by: Willy Tarreau --- net/ipv4/tcp.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 446dc4f..b80b399 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -2313,6 +2313,10 @@ int tcp_disconnect(struct sock *sk, int flags) tcp_set_ca_state(sk, TCP_CA_Open); tcp_clear_retrans(tp); inet_csk_delack_init(sk); + /* Initialize rcv_mss to TCP_MIN_MSS to avoid division by 0 + * issue in __tcp_select_window() + */ + icsk->icsk_ack.rcv_mss = TCP_MIN_MSS; tcp_init_send_head(sk); memset(&tp->rx_opt, 0, sizeof(tp->rx_opt)); __sk_dst_reset(sk); -- 2.8.0.rc2.1.gbe9624a