Re: [PATCH] audio/jack: fix use after free segfault

[Christian Schoenebeck <qemu_oss@crudebyte.com>]

On Mittwoch, 19. August 2020 00:20:07 CEST Geoffrey McRae wrote:
> > Could you please describe in more detail how you ran into this
> > situation with
> > your 2nd audio device?
> 
> Sure. Run a Windows guest with two audio devices, let it boot up, then
> restart
> the jack service to trigger the recovery routine, then attempt to use
> the 2nd
> (non-primary) audio device. Ie, go to windows audio settings to test the
> microphone of the second audio device.
> 
> When windows try to use the 2nd audio device it goes through the
> recovery
> routine triggering this fault.

I still don't quite get how this correlates. So you are forcing a restart of 
jackd on host side in between, for what purpose? To simulate the Windows 
client being kicked by jackd?

What latencies do you achieve BTW with Windows guests?

> I am aware and since these libraries are interchangeable I had assumed
> that
> JACK1 will have the same fault. If not I suppose we need to detect which
> is in
> use and change this code appropriately.

I haven't checked this in the JACK1 code base yet, but I assume JACK1 does not 
behave like JACK2 here, because the JACK API is very clear that it is the 
client's responsibility to free itself.

So it looks like a JACK2-only-bug to me.

Very weird that there is no jack_client_version() in the shared weak API (i.e. 
missing on JACK1 side).

Best regards,
Christian Schoenebeck