macsec: fix memory leaks around rx_handler (un)registration

We leak a struct macsec_rxh_data when we unregister the rx_handler in
macsec_dellink.
We also leak a struct macsec_rxh_data in register_macsec_dev if we fail
to register the rx_handler.

Fixes: c09440f7 ("macsec: introduce IEEE 802.1AE driver")
Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/macsec.c

@@ -2931,8 +2931,10 @@ static void macsec_dellink(struct net_device *dev, struct list_head *head)
 
 	unregister_netdevice_queue(dev, head);
 	list_del_rcu(&macsec->secys);
-	if (list_empty(&rxd->secys))
+	if (list_empty(&rxd->secys)) {
 		netdev_rx_handler_unregister(real_dev);
+		kfree(rxd);
+	}
 
 	macsec_del_dev(macsec);
 }
@@ -2954,9 +2956,11 @@ static int register_macsec_dev(struct net_device *real_dev,
 
 		err = netdev_rx_handler_register(real_dev, macsec_handle_frame,
 						 rxd);
-		if (err < 0)
+		if (err < 0) {
+			kfree(rxd);
 			return err;
 		}
+	}
 
 	list_add_tail_rcu(&macsec->secys, &rxd->secys);
 	return 0;