From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752368AbdIIW1m (ORCPT ); Sat, 9 Sep 2017 18:27:42 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:41842 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752008AbdIIWYz (ORCPT ); Sat, 9 Sep 2017 18:24:55 -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, "Andrei Vagin" , "David S. Miller" , "Kevin Xu" , "WANG Cong" Date: Sat, 09 Sep 2017 22:47:15 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 219/233] tcp: reset sk_rx_dst in tcp_disconnect() 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 3.16.48-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: WANG Cong commit d747a7a51b00984127a88113cdbbc26f91e9d815 upstream. We have to reset the sk->sk_rx_dst when we disconnect a TCP connection, because otherwise when we re-connect it this dst reference is simply overridden in tcp_finish_connect(). This fixes a dst leak which leads to a loopback dev refcnt leak. It is a long-standing bug, Kevin reported a very similar (if not same) bug before. Thanks to Andrei for providing such a reliable reproducer which greatly narrows down the problem. Fixes: 41063e9dd119 ("ipv4: Early TCP socket demux.") Reported-by: Andrei Vagin Reported-by: Kevin Xu Signed-off-by: Cong Wang Signed-off-by: David S. Miller [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings --- net/ipv4/tcp.c | 2 ++ 1 file changed, 2 insertions(+) --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -2367,6 +2367,8 @@ int tcp_disconnect(struct sock *sk, int tcp_init_send_head(sk); memset(&tp->rx_opt, 0, sizeof(tp->rx_opt)); __sk_dst_reset(sk); + dst_release(sk->sk_rx_dst); + sk->sk_rx_dst = NULL; WARN_ON(inet->inet_num && !icsk->icsk_bind_hash);