Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753747AbdGSLNi (ORCPT ); Wed, 19 Jul 2017 07:13:38 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:47792 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753607AbdGSLNe (ORCPT ); Wed, 19 Jul 2017 07:13:34 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Andrei Vagin , Kevin Xu , Cong Wang , "David S. Miller" Subject: [PATCH 4.4 06/57] tcp: reset sk_rx_dst in tcp_disconnect() Date: Wed, 19 Jul 2017 13:12:12 +0200 Message-Id: <20170719111250.240318103@linuxfoundation.org> X-Mailer: git-send-email 2.13.3 In-Reply-To: <20170719111249.973558472@linuxfoundation.org> References: <20170719111249.973558472@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1333 Lines: 40 4.4-stable 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 Signed-off-by: Greg Kroah-Hartman --- net/ipv4/tcp.c | 2 ++ 1 file changed, 2 insertions(+) --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -2263,6 +2263,8 @@ 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; tcp_saved_syn_free(tp); WARN_ON(inet->inet_num && !icsk->icsk_bind_hash);