HID: hid-uclogic-params: Invalid parameter check in uclogic_params_huion_init

The function performs a check on its input parameters, however, the
hdev parameter is used before the check.

Initialize the stack variables after checking the input parameters to
avoid a possible NULL pointer dereference.

Fixes: 9614219e ("HID: uclogic: Extract tablet parameter discovery into a module")
Addresses-Coverity-ID: 1443804 ("Null pointer dereference")
Signed-off-by: José Expósito <jose.exposito89@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

drivers/hid/hid-uclogic-params.c

@@ -709,9 +709,9 @@ static int uclogic_params_huion_init(struct uclogic_params *params,
 				     struct hid_device *hdev)
 {
 	int rc;
-	struct usb_device *udev = hid_to_usb_dev(hdev);
-	struct usb_interface *iface = to_usb_interface(hdev->dev.parent);
-	__u8 bInterfaceNumber = iface->cur_altsetting->desc.bInterfaceNumber;
+	struct usb_device *udev;
+	struct usb_interface *iface;
+	__u8 bInterfaceNumber;
 	bool found;
 	/* The resulting parameters (noop) */
 	struct uclogic_params p = {0, };
@@ -725,6 +725,10 @@ static int uclogic_params_huion_init(struct uclogic_params *params,
 		goto cleanup;
 	}
 
+	udev = hid_to_usb_dev(hdev);
+	iface = to_usb_interface(hdev->dev.parent);
+	bInterfaceNumber = iface->cur_altsetting->desc.bInterfaceNumber;
+
 	/* If it's not a pen interface */
 	if (bInterfaceNumber != 0) {
 		/* TODO: Consider marking the interface invalid */