From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:34994 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754298AbeCPP2P (ORCPT ); Fri, 16 Mar 2018 11:28:15 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, syzbot+845a53d13171abf8bf29@syzkaller.appspotmail.com, Florian Westphal , Pablo Neira Ayuso Subject: [PATCH 4.4 38/63] netfilter: ebtables: CONFIG_COMPAT: dont trust userland offsets Date: Fri, 16 Mar 2018 16:23:10 +0100 Message-Id: <20180316152304.286711058@linuxfoundation.org> In-Reply-To: <20180316152259.964532775@linuxfoundation.org> References: <20180316152259.964532775@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: stable-owner@vger.kernel.org List-ID: 4.4-stable 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: Greg Kroah-Hartman --- 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 @@ -2021,7 +2021,9 @@ 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; } @@ -2078,6 +2080,15 @@ 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;