From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8B710C48BDB for ; Sun, 7 Jul 2019 19:41:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6213D2082E for ; Sun, 7 Jul 2019 19:41:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727944AbfGGTlD (ORCPT ); Sun, 7 Jul 2019 15:41:03 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:57886 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727655AbfGGTiP (ORCPT ); Sun, 7 Jul 2019 15:38:15 -0400 Received: from 94.197.121.43.threembb.co.uk ([94.197.121.43] helo=deadeye) by shadbolt.decadent.org.uk with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1hkCzD-0006kM-Cc; Sun, 07 Jul 2019 20:38:11 +0100 Received: from ben by deadeye with local (Exim 4.92) (envelope-from ) id 1hkCz9-0005g7-8Y; Sun, 07 Jul 2019 20:38:07 +0100 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, Denis Kirjanov , "David S. Miller" , "Xin Long" , "Xiumei Mu" Date: Sun, 07 Jul 2019 17:54:17 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) X-Patchwork-Hint: ignore Subject: [PATCH 3.16 120/129] pptp: dst_release sk_dst_cache in pptp_sock_destruct In-Reply-To: X-SA-Exim-Connect-IP: 94.197.121.43 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 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.70-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Xin Long commit 9417d81f4f8adfe20a12dd1fadf73a618cbd945d upstream. sk_setup_caps() is called to set sk->sk_dst_cache in pptp_connect, so we have to dst_release(sk->sk_dst_cache) in pptp_sock_destruct, otherwise, the dst refcnt will leak. It can be reproduced by this syz log: r1 = socket$pptp(0x18, 0x1, 0x2) bind$pptp(r1, &(0x7f0000000100)={0x18, 0x2, {0x0, @local}}, 0x1e) connect$pptp(r1, &(0x7f0000000000)={0x18, 0x2, {0x3, @remote}}, 0x1e) Consecutive dmesg warnings will occur: unregister_netdevice: waiting for lo to become free. Usage count = 1 v1->v2: - use rcu_dereference_protected() instead of rcu_dereference_check(), as suggested by Eric. Fixes: 00959ade36ac ("PPTP: PPP over IPv4 (Point-to-Point Tunneling Protocol)") Reported-by: Xiumei Mu Signed-off-by: Xin Long Signed-off-by: David S. Miller Signed-off-by: Ben Hutchings --- drivers/net/ppp/pptp.c | 1 + 1 file changed, 1 insertion(+) --- a/drivers/net/ppp/pptp.c +++ b/drivers/net/ppp/pptp.c @@ -579,6 +579,7 @@ static void pptp_sock_destruct(struct so pppox_unbind_sock(sk); } skb_queue_purge(&sk->sk_receive_queue); + dst_release(rcu_dereference_protected(sk->sk_dst_cache, 1)); } static int pptp_create(struct net *net, struct socket *sock)