linux-kernel - [PATCH 4.4 29/58] openvswitch: fix potential out of bound access in parse

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Date:   Wed,  9 Aug 2017 12:41:41 -0700
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Liping Zhang <zlpnobody@...il.com>,
        Pravin B Shelar <pshelar@....org>,
        "David S. Miller" <davem@...emloft.net>
Subject: [PATCH 4.4 29/58] openvswitch: fix potential out of bound access in parse_ct

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Liping Zhang <zlpnobody@...il.com>


[ Upstream commit 69ec932e364b1ba9c3a2085fe96b76c8a3f71e7c ]

Before the 'type' is validated, we shouldn't use it to fetch the
ovs_ct_attr_lens's minlen and maxlen, else, out of bound access
may happen.

Fixes: 7f8a436eaa2c ("openvswitch: Add conntrack action")
Signed-off-by: Liping Zhang <zlpnobody@...il.com>
Acked-by: Pravin B Shelar <pshelar@....org>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 net/openvswitch/conntrack.c |    7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

--- a/net/openvswitch/conntrack.c
+++ b/net/openvswitch/conntrack.c
@@ -577,8 +577,8 @@ static int parse_ct(const struct nlattr
 
 	nla_for_each_nested(a, attr, rem) {
 		int type = nla_type(a);
-		int maxlen = ovs_ct_attr_lens[type].maxlen;
-		int minlen = ovs_ct_attr_lens[type].minlen;
+		int maxlen;
+		int minlen;
 
 		if (type > OVS_CT_ATTR_MAX) {
 			OVS_NLERR(log,
@@ -586,6 +586,9 @@ static int parse_ct(const struct nlattr
 				  type, OVS_CT_ATTR_MAX);
 			return -EINVAL;
 		}
+
+		maxlen = ovs_ct_attr_lens[type].maxlen;
+		minlen = ovs_ct_attr_lens[type].minlen;
 		if (nla_len(a) < minlen || nla_len(a) > maxlen) {
 			OVS_NLERR(log,
 				  "Conntrack attr type has unexpected length (type=%d, length=%d, expected=%d)",