[alsa-devel] SEGFault when optininal snd_ctl_ext_callback::read_event() not set

[Takashi Iwai]

On Thu, 05 Oct 2017 14:03:14 +0200,
Wischer, Timo (ADITG/ESB) wrote:
> 
> Hi all,
> 
> snd_ctl_ext_callback::read_event() callback is mentioned as optional
> (see http://git.alsa-project.org/?p=alsa-lib.git;a=blob;f=include/control_external.h;h=12958e70a5230de9c74029c641a395a2073c8646;hb=refs/heads/master#l239)
> 
> but there is no NULL check and the NULL pointer will be called if the read_event function callback pointer is not set.
> (see http://git.alsa-project.org/?p=alsa-lib.git;a=blob;f=src/control/control_ext.c;h=56552fa1aa0ef0e6383abf4029b63944a841c2c4;hb=refs/heads/master#l419)
> 
> I think a default function has to be provided which will be called when the callback is not set or the read_event() callback should not be marked as optional.
> 
> What is your opinion?

It should have a NULL check there, as documentation clearly states
that it's optional.

Care to submit a fix patch?


thanks,

Takashi