netfilter: nfnl_cthelper: Fix memory leak

We have memory leaks of nf_conntrack_helper & expect_policy.
Signed-off-by: Jeffy Chen <jeffy.chen@rock-chips.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/nfnetlink_cthelper.c

@@ -216,7 +216,7 @@ nfnl_cthelper_create(const struct nlattr * const tb[],
 
 	ret = nfnl_cthelper_parse_expect_policy(helper, tb[NFCTH_POLICY]);
 	if (ret < 0)
-		goto err;
+		goto err1;
 
 	strncpy(helper->name, nla_data(tb[NFCTH_NAME]), NF_CT_HELPER_NAME_LEN);
 	helper->data_len = ntohl(nla_get_be32(tb[NFCTH_PRIV_DATA_LEN]));
@@ -247,10 +247,12 @@ nfnl_cthelper_create(const struct nlattr * const tb[],
 
 	ret = nf_conntrack_helper_register(helper);
 	if (ret < 0)
-		goto err;
+		goto err2;
 
 	return 0;
-err:
+err2:
+	kfree(helper->expect_policy);
+err1:
 	kfree(helper);
 	return ret;
 }
@@ -696,6 +698,8 @@ static int nfnl_cthelper_del(struct net *net, struct sock *nfnl,
 
 			found = true;
 			nf_conntrack_helper_unregister(cur);
+			kfree(cur->expect_policy);
+			kfree(cur);
 		}
 	}
 	/* Make sure we return success if we flush and there is no helpers */
@@ -759,6 +763,8 @@ static void __exit nfnl_cthelper_exit(void)
 				continue;
 
 			nf_conntrack_helper_unregister(cur);
+			kfree(cur->expect_policy);
+			kfree(cur);
 		}
 	}
 }