[alsa-devel] snd_seq_parse_address accesses uninitialised data

Henning Thielemann alsa at henning-thielemann.de
Mon Sep 24 19:22:55 CEST 2012

On Mon, 24 Sep 2012, Takashi Iwai wrote:

> At Mon, 24 Sep 2012 16:20:50 +0200 (CEST),
> Henning Thielemann wrote:
>> For me valgrind is pretty useless if I have to manually distinguish real
>> problems from false alarms in a long list of valgrind messages. Are you
>> sure that it is generally ok to pass pointers to uninitialized data to
>> ioctl also if in this particular case the pointer is not touched by ioctl?
> Only client field is read, and this is the field properly initialized
> in alsa-lib code.  Others are fields to be filled by the kernel, so it
> doesn't matter at all what's left there.
>> If yes, then I think valgrind must be somehow teached to ignore this
>> particular case.
> I have no idea how to teach valgrind, sorry.

I also asked in the valgrind mailing list and got this answer:

Of course, I can suppress the message for me, but I expect that more 
people will stumble on it. Thus I'd prefer a resolution of the problem in 

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