act_ipt: fix a bind refcnt leak

And avoid calling tcf_hash_check() twice.

Fixes: a57f19d30b2d ("net sched: ipt action fix late binding")
Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/sched/act_ipt.c

@@ -121,10 +121,13 @@ static int __tcf_ipt_init(struct tc_action_net *tn, struct nlattr *nla,
 	}
 
 	td = (struct xt_entry_target *)nla_data(tb[TCA_IPT_TARG]);
-	if (nla_len(tb[TCA_IPT_TARG]) < td->u.target_size)
+	if (nla_len(tb[TCA_IPT_TARG]) < td->u.target_size) {
+		if (exists)
+			tcf_hash_release(a, bind);
 		return -EINVAL;
+	}
 
-	if (!tcf_hash_check(tn, index, a, bind)) {
+	if (!exists) {
 		ret = tcf_hash_create(tn, index, est, a, sizeof(*ipt), bind,
 				      false);
 		if (ret)