tcp: ulp: avoid module refcnt leak in tcp_set_ulp

__tcp_ulp_find_autoload returns tcp_ulp_ops after taking a reference on
the module. Then, if ->init fails, tcp_set_ulp propagates the error but
nothing releases that reference.

Fixes: 734942cc ("tcp: ULP infrastructure")
Signed-off-by: NSabrina Dubroca <sd@queasysnail.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv4/tcp_ulp.c

@@ -122,14 +122,14 @@ int tcp_set_ulp(struct sock *sk, const char *name)
 
 	ulp_ops = __tcp_ulp_find_autoload(name);
 	if (!ulp_ops)
-		err = -ENOENT;
-	else
-		err = ulp_ops->init(sk);
+		return -ENOENT;
 
-	if (err)
-		goto out;
+	err = ulp_ops->init(sk);
+	if (err) {
+		module_put(ulp_ops->owner);
+		return err;
+	}
 
 	icsk->icsk_ulp_ops = ulp_ops;
- out:
-	return err;
+	return 0;
 }