int usb_string(struct usb_device *dev, int index, char *buf, size_t size)
{
	unsigned char *tbuf;
	int err;

	if (dev->state == USB_STATE_SUSPENDED)
		return -EHOSTUNREACH;
	if (size <= 0 || !buf || !index)
		return -EINVAL;
	buf[0] = 0;
	tbuf = kmalloc(256, GFP_NOIO);
	if (!tbuf)
		return -ENOMEM;

	err = usb_get_langid(dev, tbuf);
	if (err < 0)
		goto errout;

	err = usb_string_sub(dev, dev->string_langid, index, tbuf);
	if (err < 0)
		goto errout;

	size--;		/* leave room for trailing NULL char in output buffer */
	err = utf16s_to_utf8s((wchar_t *) &tbuf[2], (err - 2) / 2,
			UTF16_LITTLE_ENDIAN, buf, size);
	buf[err] = 0;

	if (tbuf[1] != USB_DT_STRING)
		dev_dbg(&dev->dev,
			"wrong descriptor type %02x for string %d (\"%s\")\n",
			tbuf[1], index, buf);

 errout:
	kfree(tbuf);
	return err;
}

The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.