From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ian Wilson Subject: [PATCH] netfilter: Zero the tuple in nfnl_cthelper_parse_tuple() Date: Wed, 11 Mar 2015 21:01:55 +0000 Message-ID: <5500AD43.3070402@brocade.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 7bit To: , , Return-path: Received: from mx0a-000f0801.pphosted.com ([67.231.144.122]:53712 "EHLO mx0a-000f0801.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751582AbbCKVCJ (ORCPT ); Wed, 11 Mar 2015 17:02:09 -0400 Sender: netfilter-devel-owner@vger.kernel.org List-ID: From 0d63c5b06276d7946ba2f1f4aace4f0486ec74cf Mon Sep 17 00:00:00 2001 From: Ian Wilson Date: Wed, 11 Mar 2015 20:34:21 +0000 Subject: [PATCH] netfilter: Zero the tuple in nfnl_cthelper_parse_tuple() nfnl_cthelper_parse_tuple() is called from nfnl_cthelper_new(), nfnl_cthelper_get() and nfnl_cthelper_del(). In each case they pass a pointer to an nf_conntrack_tuple data structure local variable: struct nf_conntrack_tuple tuple; ... ret = nfnl_cthelper_parse_tuple(&tuple, tb[NFCTH_TUPLE]); The problem is that this local variable is not initialized, and nfnl_cthelper_parse_tuple() only initializes two fields: src.l3num and dst.protonum. This leaves all other fields with undefined values based on whatever is on the stack: tuple->src.l3num = ntohs(nla_get_be16(tb[NFCTH_TUPLE_L3PROTONUM])); tuple->dst.protonum = nla_get_u8(tb[NFCTH_TUPLE_L4PROTONUM]); The symptom observed was that when the rpc and tns helpers were added then traffic to port 1536 was being sent to user-space. --- net/netfilter/nfnetlink_cthelper.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/net/netfilter/nfnetlink_cthelper.c b/net/netfilter/nfnetlink_cthelper.c index a5599fc..01f4c45 100644 --- a/net/netfilter/nfnetlink_cthelper.c +++ b/net/netfilter/nfnetlink_cthelper.c @@ -77,6 +77,9 @@ nfnl_cthelper_parse_tuple(struct nf_conntrack_tuple *tuple, if (!tb[NFCTH_TUPLE_L3PROTONUM] || !tb[NFCTH_TUPLE_L4PROTONUM]) return -EINVAL; + /* Not all fields are initialized so first zero the tuple */ + memset(tuple, 0, sizeof(struct nf_conntrack_tuple)); + tuple->src.l3num = ntohs(nla_get_be16(tb[NFCTH_TUPLE_L3PROTONUM])); tuple->dst.protonum = nla_get_u8(tb[NFCTH_TUPLE_L4PROTONUM]); -- 1.9.1