Re: [PATCH] Bluetooth: Stop BCSP/H5 timer before cleaning up

[Michael Knudsen <m.knudsen@samsung.com>]

On 03/04/2014 08:14 AM, Johan Hedberg wrote:
>>> When stopping BCSP/H5, stop the retransmission timer before proceeding
>>> to clean up packet queues.  The previous code had a race condition where
>>> the timer could trigger after the packet lists and protocol structure
>>> had been removed which lead to dereferencing NULL or use-after-free bugs.
>>
>> No interest?
>
> I was just discussing this yesterday with Marcel (that we seem to have
> forgotten about this patch). The only concern is whether it's safe to
> sleep in the *_close callbacks (since you use del_timer_sync). Have you
> verified that this doesn't cause any issues?

Our internal testing was reliably triggering the crash before and
has been stable since our fix went into local trees.  I expected
sleeping to be fine since the path is in process context, and I
found that slip uses the same approach:

	drivers/net/slip/slip.c:slip_close()

I think I saw other line disciplines that did the same but I don't
recall which ones.

Btw. if this is committed, there is a small typo in the message I
used:  Instead of ``lead'' it should be ``led''.

-m.