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=-6.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,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 D426AC4346E for ; Tue, 29 Sep 2020 04:52:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 920DD20897 for ; Tue, 29 Sep 2020 04:52:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725861AbgI2Ew1 (ORCPT ); Tue, 29 Sep 2020 00:52:27 -0400 Received: from mxout70.expurgate.net ([91.198.224.70]:21195 "EHLO mxout70.expurgate.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725300AbgI2Ew0 (ORCPT ); Tue, 29 Sep 2020 00:52:26 -0400 Received: from [127.0.0.1] (helo=localhost) by relay.expurgate.net with smtp (Exim 4.92) (envelope-from ) id 1kN7ce-000XXd-Kp; Tue, 29 Sep 2020 06:52:16 +0200 Received: from [195.243.126.94] (helo=securemail.tdt.de) by relay.expurgate.net with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1kN7cc-0002oc-8s; Tue, 29 Sep 2020 06:52:14 +0200 Received: from securemail.tdt.de (localhost [127.0.0.1]) by securemail.tdt.de (Postfix) with ESMTP id 2FF2124004B; Tue, 29 Sep 2020 06:52:13 +0200 (CEST) Received: from mail.dev.tdt.de (unknown [10.2.4.42]) by securemail.tdt.de (Postfix) with ESMTP id 215FE240047; Tue, 29 Sep 2020 06:52:13 +0200 (CEST) Received: from mail.dev.tdt.de (localhost [IPv6:::1]) by mail.dev.tdt.de (Postfix) with ESMTP id B9BA920CA0; Tue, 29 Sep 2020 04:52:12 +0000 (UTC) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Date: Tue, 29 Sep 2020 06:52:12 +0200 From: Martin Schiller To: David Miller Cc: andrew.hendry@gmail.com, kuba@kernel.org, edumazet@google.com, xiyuyang19@fudan.edu.cn, linux-x25@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] net/x25: Fix null-ptr-deref in x25_connect Organization: TDT AG In-Reply-To: <20200928.184326.1754311969939569006.davem@davemloft.net> References: <20200928092327.329-1-ms@dev.tdt.de> <20200928.184326.1754311969939569006.davem@davemloft.net> Message-ID: <162dd41ee6717ad46e0a37003d922ea1@dev.tdt.de> X-Sender: ms@dev.tdt.de User-Agent: Roundcube Webmail/1.1.5 X-purgate: clean X-purgate-ID: 151534::1601355134-0001EE7D-F1ADBCC2/0/0 X-purgate-type: clean Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2020-09-29 03:43, David Miller wrote: > From: Martin Schiller > Date: Mon, 28 Sep 2020 11:23:27 +0200 > >> diff --git a/net/x25/af_x25.c b/net/x25/af_x25.c >> index 0bbb283f23c9..0524a5530b91 100644 >> --- a/net/x25/af_x25.c >> +++ b/net/x25/af_x25.c >> @@ -820,7 +820,7 @@ static int x25_connect(struct socket *sock, struct >> sockaddr *uaddr, >> >> rc = x25_wait_for_connection_establishment(sk); >> if (rc) >> - goto out_put_neigh; >> + goto out; > > If x25_wait_for_connection_establishment() returns because of an > interrupting > signal, we are not going to call x25_disconnect(). > > The case you are fixing only applies _sometimes_ when > x25_wait_for_connection_establishment() returns. But not always. > > That neighbour has to be released at this spot otherwise. OK, thanks for the hint. So I think the simplest solution would be to check that x25->neighbour is != NULL like this: diff --git a/net/x25/af_x25.c b/net/x25/af_x25.c index 0bbb283f23c9..046d3fee66a9 100644 --- a/net/x25/af_x25.c +++ b/net/x25/af_x25.c @@ -825,7 +825,7 @@ static int x25_connect(struct socket *sock, struct sockaddr *uaddr, sock->state = SS_CONNECTED; rc = 0; out_put_neigh: - if (rc) { + if (rc && x25->neighbour) { read_lock_bh(&x25_list_lock); x25_neigh_put(x25->neighbour); x25->neighbour = NULL; -- What do you think? If that would be OK, I'll send a v2 of the Patch. - Martin