s390/qeth: validate device-provided MAC address

It's good practice to not blindly trust what the HW offers.
Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Reviewed-by: Alexandra Winter <wintera@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/s390/net/qeth_l3_main.c

@@ -920,6 +920,8 @@ static int qeth_l3_iqd_read_initial_mac_cb(struct qeth_card *card,
 
 	if (cmd->hdr.return_code)
 		return -EIO;
+	if (!is_valid_ether_addr(cmd->data.create_destroy_addr.mac_addr))
+		return -EADDRNOTAVAIL;
 
 	ether_addr_copy(card->dev->dev_addr,
 			cmd->data.create_destroy_addr.mac_addr);