phonet: refcount leak in pep_sock_accep

sock_hold(sk) is invoked in pep_sock_accept(), but __sock_put(sk) is not
invoked in subsequent failure branches(pep_accept_conn() != 0).

Signed-off-by: Hangyu Hua <hbh25y@gmail.com>
Link: https://lore.kernel.org/r/20211209082839.33985-1-hbh25y@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net/phonet/pep.c

@@ -868,6 +868,7 @@ static struct sock *pep_sock_accept(struct sock *sk, int flags, int *errp,
 
 	err = pep_accept_conn(newsk, skb);
 	if (err) {
+		__sock_put(sk);
 		sock_put(newsk);
 		newsk = NULL;
 		goto drop;