static void hci_uart_tty_receive(struct tty_struct *tty, const u8 *data,
				 char *flags, int count)
{
	struct hci_uart *hu = tty->disc_data;

	if (!hu || tty != hu->tty)
		return;

	percpu_down_read(&hu->proto_lock);

	if (!test_bit(HCI_UART_PROTO_READY, &hu->flags)) {
		percpu_up_read(&hu->proto_lock);
		return;
	}

	/* It does not need a lock here as it is already protected by a mutex in
	 * tty caller
	 */
	hu->proto->recv(hu, data, count);
	percpu_up_read(&hu->proto_lock);

	if (hu->hdev)
		hu->hdev->stat.byte_rx += count;

	tty_unthrottle(tty);
}

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 Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.