[NETFILTER]: nf_conntrack: check address family when finding protocol module

__nf_conntrack_{l3}proto_find() doesn't check the passed protocol family,
then it's possible to touch out of the array which has only AF_MAX items.

Spotted by Pablo Neira Ayuso.
Signed-off-by: Yasuyuki Kozakai <yasuyuki.kozakai@toshiba.co.jp>
Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/netfilter/nf_conntrack_l3proto.h

@@ -88,12 +88,6 @@ extern struct nf_conntrack_l3proto *nf_ct_l3protos[AF_MAX];
 extern int nf_conntrack_l3proto_register(struct nf_conntrack_l3proto *proto);
 extern void nf_conntrack_l3proto_unregister(struct nf_conntrack_l3proto *proto);
 
-static inline struct nf_conntrack_l3proto *
-__nf_ct_l3proto_find(u_int16_t l3proto)
-{
-	return nf_ct_l3protos[l3proto];
-}
-
 extern struct nf_conntrack_l3proto *
 nf_ct_l3proto_find_get(u_int16_t l3proto);
 
@@ -103,4 +97,13 @@ extern void nf_ct_l3proto_put(struct nf_conntrack_l3proto *p);
 extern struct nf_conntrack_l3proto nf_conntrack_l3proto_ipv4;
 extern struct nf_conntrack_l3proto nf_conntrack_l3proto_ipv6;
 extern struct nf_conntrack_l3proto nf_conntrack_generic_l3proto;
+
+static inline struct nf_conntrack_l3proto *
+__nf_ct_l3proto_find(u_int16_t l3proto)
+{
+	if (unlikely(l3proto >= AF_MAX))
+		return &nf_conntrack_generic_l3proto;
+	return nf_ct_l3protos[l3proto];
+}
+
 #endif /*_NF_CONNTRACK_L3PROTO_H*/

net/netfilter/nf_conntrack_core.c

@@ -188,7 +188,7 @@ extern struct nf_conntrack_protocol nf_conntrack_generic_protocol;
 struct nf_conntrack_protocol *
 __nf_ct_proto_find(u_int16_t l3proto, u_int8_t protocol)
 {
-	if (unlikely(nf_ct_protos[l3proto] == NULL))
+	if (unlikely(l3proto >= AF_MAX || nf_ct_protos[l3proto] == NULL))
 		return &nf_conntrack_generic_protocol;
 
 	return nf_ct_protos[l3proto][protocol];