net: hso: fix muxed tty registration

If resource allocation and registration fail for a muxed tty device
(e.g. if there are no more minor numbers) the driver should not try to
deregister the never-registered (or already-deregistered) tty.

Fix up the error handling to avoid dereferencing a NULL pointer when
attempting to remove the character device.

Fixes: 72dc1c096c70 ("HSO: add option hso driver")
Cc: [e-mail] # 2.6.27
Signed-off-by: Johan Hovold <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

drivers/net/usb/hso.c

···
 
 	serial = kzalloc(sizeof(*serial), GFP_KERNEL);
 	if (!serial)
-		goto exit;
+		goto err_free_dev;
 
 	hso_dev->port_data.dev_serial = serial;
 	serial->parent = hso_dev;
 
 	if (hso_serial_common_create
 	    (serial, 1, CTRL_URB_RX_SIZE, CTRL_URB_TX_SIZE))
-		goto exit;
+		goto err_free_serial;
 
 	serial->tx_data_length--;
 	serial->write_data = hso_mux_serial_write_data;
···
 	/* done, return it */
 	return hso_dev;
 
-exit:
-	if (serial) {
-		tty_unregister_device(tty_drv, serial->minor);
-		kfree(serial);
-	}
+err_free_serial:
+	kfree(serial);
+err_free_dev:
 	kfree(hso_dev);
 	return NULL;