netfilter: ipset: off by one in ip_set_nfnl_get_byindex()

The ->ip_set_list[] array is initialized in ip_set_net_init() and it
has ->ip_set_max elements so this check should be >= instead of >
otherwise we are off by one.
Signed-off-by: NDan Carpenter <dan.carpenter@oracle.com>
Acked-by: NJozsef Kadlecsik <kadlec@blackhole.kfki.hu>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/ipset/ip_set_core.c

@@ -659,7 +659,7 @@ ip_set_nfnl_get_byindex(struct net *net, ip_set_id_t index)
 	struct ip_set *set;
 	struct ip_set_net *inst = ip_set_pernet(net);
 
-	if (index > inst->ip_set_max)
+	if (index >= inst->ip_set_max)
 		return IPSET_INVALID_ID;
 
 	nfnl_lock(NFNL_SUBSYS_IPSET);