[NETFILTER]: conntrack: fix refcount leak when finding expectation

All users of __{ip,nf}_conntrack_expect_find() don't expect that
it increments the reference count of expectation.

Signed-off-by: Yasuyuki Kozakai <yasuyuki.kozakai@toshiba.co.jp>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/netfilter/ip_conntrack_core.c

@@ -225,10 +225,8 @@ __ip_conntrack_expect_find(const struct ip_conntrack_tuple *tuple)
 	struct ip_conntrack_expect *i;
 
 	list_for_each_entry(i, &ip_conntrack_expect_list, list) {
-		if (ip_ct_tuple_mask_cmp(tuple, &i->tuple, &i->mask)) {
-			atomic_inc(&i->use);
+		if (ip_ct_tuple_mask_cmp(tuple, &i->tuple, &i->mask))
 			return i;
-		}
 	}
 	return NULL;
 }
@@ -241,6 +239,8 @@ ip_conntrack_expect_find(const struct ip_conntrack_tuple *tuple)
 
 	read_lock_bh(&ip_conntrack_lock);
 	i = __ip_conntrack_expect_find(tuple);
+	if (i)
+		atomic_inc(&i->use);
 	read_unlock_bh(&ip_conntrack_lock);
 
 	return i;

net/netfilter/nf_conntrack_core.c

@@ -469,10 +469,8 @@ __nf_conntrack_expect_find(const struct nf_conntrack_tuple *tuple)
 	struct nf_conntrack_expect *i;
 
 	list_for_each_entry(i, &nf_conntrack_expect_list, list) {
-		if (nf_ct_tuple_mask_cmp(tuple, &i->tuple, &i->mask)) {
-			atomic_inc(&i->use);
+		if (nf_ct_tuple_mask_cmp(tuple, &i->tuple, &i->mask))
 			return i;
-		}
 	}
 	return NULL;
 }
@@ -485,6 +483,8 @@ nf_conntrack_expect_find(const struct nf_conntrack_tuple *tuple)
 
 	read_lock_bh(&nf_conntrack_lock);
 	i = __nf_conntrack_expect_find(tuple);
+	if (i)
+		atomic_inc(&i->use);
 	read_unlock_bh(&nf_conntrack_lock);
 
 	return i;