Re: [PATCH] drivers/bluetooth/hci_ldisc.c: fix possible NULL dereferences

[Eugene Teo <eteo@redhat.com>]

Hi Marcel,

Marcel Holtmann wrote:
>>>> Commit 22ad42033b7d2b3d7928fba9f89d1c7f8a3c9581 did not completely fix all 
>>>> the possible NULL dereferences. Besides hci_uart_close(), we also need to 
>>>> make sure that hdev is valid before calling hci_{unregister,free}_dev().
>>> I don't see any issue. Without HCI_UART_PROTO_SET, the hdev will never
>>> be registered. So no need to protect it twice.
>> Correct me if I am wrong. HCI_UART_PROTO_SET bit is only set if hci_uart_tty_ioctl()
>> is called with HCIUARTSETPROTO. Is it possible for the HCI device to be registered
>> and then unregistered without setting the HCI_UART_PROTO_SET bit in hdev->flags?
> 
> look at the code. The hci_uart_tty_ioctl() is the only function that can
> register the HCI device. So besides opening the TTY and set the line
> discipline, you also have to the set the UART protocol running on top. I
> don't see any way you can achieve to register a HCI device without
> setting the HCI_UART_PROTO_SET bit in hu->flags.

Ok. Thanks for the explanation.

Eugene