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=-5.5 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 06397C433E1 for ; Wed, 29 Jul 2020 21:46:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E14C720838 for ; Wed, 29 Jul 2020 21:46:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727085AbgG2VqM (ORCPT ); Wed, 29 Jul 2020 17:46:12 -0400 Received: from correo.us.es ([193.147.175.20]:38246 "EHLO mail.us.es" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726496AbgG2VqL (ORCPT ); Wed, 29 Jul 2020 17:46:11 -0400 Received: from antivirus1-rhel7.int (unknown [192.168.2.11]) by mail.us.es (Postfix) with ESMTP id 248E0FB374 for ; Wed, 29 Jul 2020 23:46:10 +0200 (CEST) Received: from antivirus1-rhel7.int (localhost [127.0.0.1]) by antivirus1-rhel7.int (Postfix) with ESMTP id 1800DDA78F for ; Wed, 29 Jul 2020 23:46:10 +0200 (CEST) Received: by antivirus1-rhel7.int (Postfix, from userid 99) id 0D170DA72F; Wed, 29 Jul 2020 23:46:10 +0200 (CEST) Received: from antivirus1-rhel7.int (localhost [127.0.0.1]) by antivirus1-rhel7.int (Postfix) with ESMTP id CAD81DA73D; Wed, 29 Jul 2020 23:46:07 +0200 (CEST) Received: from 192.168.1.97 (192.168.1.97) by antivirus1-rhel7.int (F-Secure/fsigk_smtp/550/antivirus1-rhel7.int); Wed, 29 Jul 2020 23:46:07 +0200 (CEST) X-Virus-Status: clean(F-Secure/fsigk_smtp/550/antivirus1-rhel7.int) Received: from us.es (unknown [90.77.255.23]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) (Authenticated sender: 1984lsi) by entrada.int (Postfix) with ESMTPSA id 941A74265A2F; Wed, 29 Jul 2020 23:46:07 +0200 (CEST) Date: Wed, 29 Jul 2020 23:46:07 +0200 X-SMTPAUTHUS: auth mail.us.es From: Pablo Neira Ayuso To: Will McVicker Cc: security@kernel.org, Jozsef Kadlecsik , Florian Westphal , "David S. Miller" , Alexey Kuznetsov , Hideaki YOSHIFUJI , netfilter-devel@vger.kernel.org, coreteam@netfilter.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@android.com Subject: Re: [PATCH 1/1] netfilter: nat: add range checks for access to nf_nat_l[34]protos[] Message-ID: <20200729214607.GA30831@salvia> References: <20200727175720.4022402-1-willmcvicker@google.com> <20200727175720.4022402-2-willmcvicker@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200727175720.4022402-2-willmcvicker@google.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-Virus-Scanned: ClamAV using ClamSMTP Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Hi Will, On Mon, Jul 27, 2020 at 05:57:20PM +0000, Will McVicker wrote: > The indexes to the nf_nat_l[34]protos arrays come from userspace. So we > need to make sure that before indexing the arrays, we verify the index > is within the array bounds in order to prevent an OOB memory access. > Here is an example kernel panic on 4.14.180 when userspace passes in an > index greater than NFPROTO_NUMPROTO. > > Internal error: Oops - BUG: 0 [#1] PREEMPT SMP > Modules linked in:... > Process poc (pid: 5614, stack limit = 0x00000000a3933121) > CPU: 4 PID: 5614 Comm: poc Tainted: G S W O 4.14.180-g051355490483 > Hardware name: Qualcomm Technologies, Inc. SM8150 V2 PM8150 Google Inc. MSM > task: 000000002a3dfffe task.stack: 00000000a3933121 > pc : __cfi_check_fail+0x1c/0x24 > lr : __cfi_check_fail+0x1c/0x24 > ... > Call trace: > __cfi_check_fail+0x1c/0x24 > name_to_dev_t+0x0/0x468 > nfnetlink_parse_nat_setup+0x234/0x258 If this oops is only triggerable from userspace, I think a sanity check in nfnetlink_parse_nat_setup should suffice to reject unsupported layer 3 and layer 4 protocols. I mean, in this patch I see more chunks in the packet path, such as nf_nat_l3proto_ipv4 that should never happen. I would just fix the userspace ctnetlink path. BTW, do you have a Fixes: tag for this? This will be useful for -stable maintainer to pick up this fix. Thanks.