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 D48AFC433DF for ; Fri, 14 Aug 2020 09:59:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B3A0F20716 for ; Fri, 14 Aug 2020 09:59:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726738AbgHNJ7u (ORCPT ); Fri, 14 Aug 2020 05:59:50 -0400 Received: from correo.us.es ([193.147.175.20]:39790 "EHLO mail.us.es" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726012AbgHNJ7u (ORCPT ); Fri, 14 Aug 2020 05:59:50 -0400 Received: from antivirus1-rhel7.int (unknown [192.168.2.11]) by mail.us.es (Postfix) with ESMTP id 9B47CC22E5 for ; Fri, 14 Aug 2020 11:59:48 +0200 (CEST) Received: from antivirus1-rhel7.int (localhost [127.0.0.1]) by antivirus1-rhel7.int (Postfix) with ESMTP id 8C93DDA840 for ; Fri, 14 Aug 2020 11:59:48 +0200 (CEST) Received: by antivirus1-rhel7.int (Postfix, from userid 99) id 81DD9DA84F; Fri, 14 Aug 2020 11:59:48 +0200 (CEST) Received: from antivirus1-rhel7.int (localhost [127.0.0.1]) by antivirus1-rhel7.int (Postfix) with ESMTP id 68C3BDA840; Fri, 14 Aug 2020 11:59:46 +0200 (CEST) Received: from 192.168.1.97 (192.168.1.97) by antivirus1-rhel7.int (F-Secure/fsigk_smtp/550/antivirus1-rhel7.int); Fri, 14 Aug 2020 11:59:46 +0200 (CEST) X-Virus-Status: clean(F-Secure/fsigk_smtp/550/antivirus1-rhel7.int) Received: from us.es (170.pool85-48-185.static.orange.es [85.48.185.170]) (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 F1C6842EF42A; Fri, 14 Aug 2020 11:59:45 +0200 (CEST) Date: Fri, 14 Aug 2020 11:59:43 +0200 X-SMTPAUTHUS: auth mail.us.es From: Pablo Neira Ayuso To: Florian Westphal Cc: netfilter-devel@vger.kernel.org, hch@lst.de, syzkaller-bugs@googlegroups.com, netdev@vger.kernel.org, syzbot+5accb5c62faa1d346480@syzkaller.appspotmail.com Subject: Re: [PATCH nf] netfilter/ebtables: reject bogus getopt len value Message-ID: <20200814095943.GC5816@salvia> References: <000000000000ece9db05ac4054e8@google.com> <20200813074611.281558-1-fw@strlen.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200813074611.281558-1-fw@strlen.de> 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 On Thu, Aug 13, 2020 at 09:46:11AM +0200, Florian Westphal wrote: > syzkaller reports splat: > ------------[ cut here ]------------ > Buffer overflow detected (80 < 137)! > Call Trace: > do_ebt_get_ctl+0x2b4/0x790 net/bridge/netfilter/ebtables.c:2317 > nf_getsockopt+0x72/0xd0 net/netfilter/nf_sockopt.c:116 > ip_getsockopt net/ipv4/ip_sockglue.c:1778 [inline] > > caused by a copy-to-user with a too-large "*len" value. > This adds a argument check on *len just like in the non-compat version > of the handler. > > Before the "Fixes" commit, the reproducer fails with -EINVAL as > expected: > 1. core calls the "compat" getsockopt version > 2. compat getsockopt version detects the *len value is possibly > in 64-bit layout (*len != compat_len) > 3. compat getsockopt version delegates everything to native getsockopt > version > 4. native getsockopt rejects invalid *len > > -> compat handler only sees len == sizeof(compat_struct) for GET_ENTRIES. > > After the refactor, event sequence is: > 1. getsockopt calls "compat" version (len != native_len) > 2. compat version attempts to copy *len bytes, where *len is random > value from userspace Applied, thanks.