From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753687AbeE3Lss (ORCPT ); Wed, 30 May 2018 07:48:48 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:60630 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751593AbeE3LG4 (ORCPT ); Wed, 30 May 2018 07:06:56 -0400 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, "" , "Pablo Neira Ayuso" , "Florian Westphal" Date: Wed, 30 May 2018 11:52:41 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 004/153] netfilter: ebtables: CONFIG_COMPAT: don't trust userland offsets In-Reply-To: X-SA-Exim-Connect-IP: 2a02:8011:400e:2:6f00:88c8:c921:d332 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 List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.2.102-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Florian Westphal commit b71812168571fa55e44cdd0254471331b9c4c4c6 upstream. We need to make sure the offsets are not out of range of the total size. Also check that they are in ascending order. The WARN_ON triggered by syzkaller (it sets panic_on_warn) is changed to also bail out, no point in continuing parsing. Briefly tested with simple ruleset of -A INPUT --limit 1/s' --log plus jump to custom chains using 32bit ebtables binary. Reported-by: Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso Signed-off-by: Ben Hutchings --- net/bridge/netfilter/ebtables.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) --- a/net/bridge/netfilter/ebtables.c +++ b/net/bridge/netfilter/ebtables.c @@ -2004,7 +2004,9 @@ static int ebt_size_mwt(struct compat_eb if (match_kern) match_kern->match_size = ret; - WARN_ON(type == EBT_COMPAT_TARGET && size_left); + if (WARN_ON(type == EBT_COMPAT_TARGET && size_left)) + return -EINVAL; + match32 = (struct compat_ebt_entry_mwt *) buf; } @@ -2061,6 +2063,15 @@ static int size_entry_mwt(struct ebt_ent * * offsets are relative to beginning of struct ebt_entry (i.e., 0). */ + for (i = 0; i < 4 ; ++i) { + if (offsets[i] >= *total) + return -EINVAL; + if (i == 0) + continue; + if (offsets[i-1] > offsets[i]) + return -EINVAL; + } + for (i = 0, j = 1 ; j < 4 ; j++, i++) { struct compat_ebt_entry_mwt *match32; unsigned int size;