From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752402AbdIIWzx (ORCPT ); Sat, 9 Sep 2017 18:55:53 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:41299 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751751AbdIIWYk (ORCPT ); Sat, 9 Sep 2017 18:24:40 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Andrey Konovalov" , "Eric Dumazet" , "Neal Cardwell" , "David S. Miller" , "Yuchung Cheng" , "Wei Wang" Date: Sat, 09 Sep 2017 22:47:40 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 098/106] tcp: initialize rcv_mss to TCP_MIN_MSS instead of 0 In-Reply-To: X-SA-Exim-Connect-IP: 2a02:8011:400e:2:6f00:88c8:c921:d332 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.2.93-rc1 review patch. If anyone has any objections, please let me know. ------------------ 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: Ben Hutchings --- net/ipv4/tcp.c | 4 ++++ 1 file changed, 4 insertions(+) --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -2106,6 +2106,10 @@ int tcp_disconnect(struct sock *sk, int 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);