static void usb_console_write(struct console *co,
					const char *buf, unsigned count)
{
	static struct usbcons_info *info = &usbcons_info;
	struct usb_serial_port *port = info->port;
	struct usb_serial *serial;
	int retval = -ENODEV;

	if (!port || port->serial->dev->state == USB_STATE_NOTATTACHED)
		return;
	serial = port->serial;

	if (count == 0)
		return;

	dev_dbg(&port->dev, "%s - %d byte(s)\n", __func__, count);

	if (!port->port.console) {
		dev_dbg(&port->dev, "%s - port not opened\n", __func__);
		return;
	}

	while (count) {
		unsigned int i;
		unsigned int lf;
		/* search for LF so we can insert CR if necessary */
		for (i = 0, lf = 0 ; i < count ; i++) {
			if (*(buf + i) == 10) {
				lf = 1;
				i++;
				break;
			}
		}
		/* pass on to the driver specific version of this function if
		   it is available */
		retval = serial->type->write(NULL, port, buf, i);
		dev_dbg(&port->dev, "%s - write: %d\n", __func__, retval);
		if (lf) {
			/* append CR after LF */
			unsigned char cr = 13;
			retval = serial->type->write(NULL, port, &cr, 1);
			dev_dbg(&port->dev, "%s - write cr: %d\n",
							__func__, retval);
		}
		buf += i;
		count -= i;
	}
}

The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.