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=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 4605BC11F67 for ; Fri, 2 Jul 2021 00:56:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2964A61410 for ; Fri, 2 Jul 2021 00:56:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234560AbhGBA7D (ORCPT ); Thu, 1 Jul 2021 20:59:03 -0400 Received: from mail.netfilter.org ([217.70.188.207]:41992 "EHLO mail.netfilter.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230369AbhGBA7B (ORCPT ); Thu, 1 Jul 2021 20:59:01 -0400 Received: from netfilter.org (unknown [90.77.255.23]) by mail.netfilter.org (Postfix) with ESMTPSA id A781A60705; Fri, 2 Jul 2021 02:56:22 +0200 (CEST) Date: Fri, 2 Jul 2021 02:56:26 +0200 From: Pablo Neira Ayuso To: Vasily Averin Cc: Jozsef Kadlecsik , Florian Westphal , netfilter-devel@vger.kernel.org, coreteam@netfilter.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH NETFILTER v2] netfilter: gre: nf_ct_gre_keymap_flush() removal Message-ID: <20210702005626.GB29227@salvia> References: <0e3cdbe6-33f7-60b0-64ca-72f6f6a42df8@virtuozzo.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <0e3cdbe6-33f7-60b0-64ca-72f6f6a42df8@virtuozzo.com> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jul 01, 2021 at 08:02:24AM +0300, Vasily Averin wrote: > nf_ct_gre_keymap_flush() is useless. > It is called from nf_conntrack_cleanup_net_list() only and tries to remove > nf_ct_gre_keymap entries from pernet gre keymap list. Though: > a) at this point the list should already be empty, all its entries were > deleted during the conntracks cleanup, because > nf_conntrack_cleanup_net_list() executes nf_ct_iterate_cleanup(kill_all) > before nf_conntrack_proto_pernet_fini(): > nf_conntrack_cleanup_net_list > +- nf_ct_iterate_cleanup > | nf_ct_put > | nf_conntrack_put > | nf_conntrack_destroy > | destroy_conntrack > | destroy_gre_conntrack > | nf_ct_gre_keymap_destroy > `- nf_conntrack_proto_pernet_fini > nf_ct_gre_keymap_flush > > b) Let's say we find that the keymap list is not empty. This means netns > still has a conntrack associated with gre, in which case we should not free > its memory, because this will lead to a double free and related crashes. > However I doubt it could have gone unnoticed for years, obviously > this does not happen in real life. So I think we can remove > both nf_ct_gre_keymap_flush() and nf_conntrack_proto_pernet_fini(). Also applied. I think nf_ct_gre_keymap_flush() became useless when the GRE was de-modularized (built-in into nf_conntrack).