netdev - [PATCH 07/18] netfilter: ipset: Check IPSET_ATTR

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Date:	Tue, 15 Mar 2016 02:27:51 +0100
From:	Pablo Neira Ayuso <pablo@...filter.org>
To:	netfilter-devel@...r.kernel.org
Cc:	davem@...emloft.net, netdev@...r.kernel.org
Subject: [PATCH 07/18] netfilter: ipset: Check IPSET_ATTR_ETHER netlink attribute length

From: Jozsef Kadlecsik <kadlec@...ckhole.kfki.hu>

Julia Lawall pointed out that IPSET_ATTR_ETHER netlink attribute length
was not checked explicitly, just for the maximum possible size. Malicious
netlink clients could send shorter attribute and thus resulting a kernel
read after the buffer.

The patch adds the explicit length checkings.

Reported-by: Julia Lawall <julia.lawall@...6.fr>
Signed-off-by: Jozsef Kadlecsik <kadlec@...ckhole.kfki.hu>
---
 net/netfilter/ipset/ip_set_bitmap_ipmac.c | 2 ++
 net/netfilter/ipset/ip_set_hash_mac.c     | 3 ++-
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/net/netfilter/ipset/ip_set_bitmap_ipmac.c b/net/netfilter/ipset/ip_set_bitmap_ipmac.c
index 29dde20..9a065f6 100644
--- a/net/netfilter/ipset/ip_set_bitmap_ipmac.c
+++ b/net/netfilter/ipset/ip_set_bitmap_ipmac.c
@@ -267,6 +267,8 @@ bitmap_ipmac_uadt(struct ip_set *set, struct nlattr *tb[],
 
 	e.id = ip_to_id(map, ip);
 	if (tb[IPSET_ATTR_ETHER]) {
+		if (nla_len(tb[IPSET_ATTR_ETHER]) != ETH_ALEN)
+			return -IPSET_ERR_PROTOCOL;
 		memcpy(e.ether, nla_data(tb[IPSET_ATTR_ETHER]), ETH_ALEN);
 		e.add_mac = 1;
 	}
diff --git a/net/netfilter/ipset/ip_set_hash_mac.c b/net/netfilter/ipset/ip_set_hash_mac.c
index f1e7d2c..8f004ed 100644
--- a/net/netfilter/ipset/ip_set_hash_mac.c
+++ b/net/netfilter/ipset/ip_set_hash_mac.c
@@ -110,7 +110,8 @@ hash_mac4_uadt(struct ip_set *set, struct nlattr *tb[],
 	if (tb[IPSET_ATTR_LINENO])
 		*lineno = nla_get_u32(tb[IPSET_ATTR_LINENO]);
 
-	if (unlikely(!tb[IPSET_ATTR_ETHER]))
+	if (unlikely(!tb[IPSET_ATTR_ETHER] ||
+		     nla_len(tb[IPSET_ATTR_ETHER]) != ETH_ALEN))
 		return -IPSET_ERR_PROTOCOL;
 
 	ret = ip_set_get_extensions(set, tb, &ext);
-- 
2.1.4