static int hci_uart_setup(struct hci_dev *hdev)
{
	struct hci_uart *hu = hci_get_drvdata(hdev);
	struct hci_rp_read_local_version *ver;
	struct sk_buff *skb;
	unsigned int speed;
	int err;

	/* Init speed if any */
	if (hu->init_speed)
		speed = hu->init_speed;
	else if (hu->proto->init_speed)
		speed = hu->proto->init_speed;
	else
		speed = 0;

	if (speed)
		hci_uart_set_baudrate(hu, speed);

	/* Operational speed if any */
	if (hu->oper_speed)
		speed = hu->oper_speed;
	else if (hu->proto->oper_speed)
		speed = hu->proto->oper_speed;
	else
		speed = 0;

	if (hu->proto->set_baudrate && speed) {
		err = hu->proto->set_baudrate(hu, speed);
		if (!err)
			hci_uart_set_baudrate(hu, speed);
	}

	if (hu->proto->setup)
		return hu->proto->setup(hu);

	if (!test_bit(HCI_UART_VND_DETECT, &hu->hdev_flags))
		return 0;

	skb = __hci_cmd_sync(hdev, HCI_OP_READ_LOCAL_VERSION, 0, NULL,
			     HCI_INIT_TIMEOUT);
	if (IS_ERR(skb)) {
		BT_ERR("%s: Reading local version information failed (%ld)",
		       hdev->name, PTR_ERR(skb));
		return 0;
	}

	if (skb->len != sizeof(*ver)) {
		BT_ERR("%s: Event length mismatch for version information",
		       hdev->name);
		goto done;
	}

	ver = (struct hci_rp_read_local_version *)skb->data;

	switch (le16_to_cpu(ver->manufacturer)) {
#ifdef CONFIG_BT_HCIUART_INTEL
	case 2:
		hdev->set_bdaddr = btintel_set_bdaddr;
		btintel_check_bdaddr(hdev);
		break;
#endif
#ifdef CONFIG_BT_HCIUART_BCM
	case 15:
		hdev->set_bdaddr = btbcm_set_bdaddr;
		btbcm_check_bdaddr(hdev);
		break;
#endif
	default:
		break;
	}

done:
	kfree_skb(skb);
	return 0;
}

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 Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.