staging: vt6656: use off stack for in buffer USB transfers.

commit 05c0cf88 upstream.

Since 4.9 mandated USB buffers to be heap allocated. This causes
the driver to fail.

Create buffer for USB transfers.
Signed-off-by: Malcolm Priestley <tvboxspy@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/vt6656/usbpipe.c

@@ -78,15 +78,28 @@ int vnt_control_in(struct vnt_private *priv, u8 request, u16 value,
 		u16 index, u16 length, u8 *buffer)
 {
 	int status;
+	u8 *usb_buffer;
 
 	if (test_bit(DEVICE_FLAGS_DISCONNECTED, &priv->flags))
 		return STATUS_FAILURE;
 
 	mutex_lock(&priv->usb_lock);
 
+	usb_buffer = kmalloc(length, GFP_KERNEL);
+	if (!usb_buffer) {
+		mutex_unlock(&priv->usb_lock);
+		return -ENOMEM;
+	}
+
 	status = usb_control_msg(priv->usb,
-		usb_rcvctrlpipe(priv->usb, 0), request, 0xc0, value,
-			index, buffer, length, USB_CTL_WAIT);
+				 usb_rcvctrlpipe(priv->usb, 0),
+				 request, 0xc0, value,
+				 index, usb_buffer, length, USB_CTL_WAIT);
+
+	if (status == length)
+		memcpy(buffer, usb_buffer, length);
+
+	kfree(usb_buffer);
 
 	mutex_unlock(&priv->usb_lock);