[alsa-devel] [PATCH] mixer: Fix memory leak for more than 16 file descriptor case

[David Fries]

I realized that after I sent it, and I wasn't sure if that was going
to be the solution anyway.  I sent another patch and added you as
reviewed by if that's okay.

On Tue, Jan 07, 2020 at 02:03:48PM +0100, Takashi Iwai wrote:
> On Mon, 06 Jan 2020 22:41:29 +0100,
> David Fries wrote:
> > 
> > ---
> > I saw this when digging through the source code, wrote up a test case,
> > and verified with valgrind. I don't have that many sound cards so I
> > modified mixer.c to always take the conditional. alloca seemed like
> > the least effort way to fix this. Other thoughts were to test pfds !=
> > spfds and free, but given how little bytes would be allocated putting
> > on the stack seems reasonable.
> 
> Looks good to me.
> 
> Could you give your sign-off?  It's not strictly needed for alsa-lib,
> but we prefer having it.
> 
> 
> thanks,
> 
> Takashi
> 
> > 
> > I also created the github pull request 20.
> > https://github.com/alsa-project/alsa-lib/pull/20
> > 
> >  src/mixer/mixer.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/src/mixer/mixer.c b/src/mixer/mixer.c
> > index 82056474..b1af9945 100644
> > --- a/src/mixer/mixer.c
> > +++ b/src/mixer/mixer.c
> > @@ -767,7 +767,7 @@ int snd_mixer_wait(snd_mixer_t *mixer, int timeout)
> >  	if (count < 0)
> >  		return count;
> >  	if ((unsigned int) count > sizeof(spfds) / sizeof(spfds[0])) {
> > -		pfds = malloc(count * sizeof(*pfds));
> > +		pfds = alloca(count * sizeof(*pfds));
> >  		if (!pfds)
> >  			return -ENOMEM;
> >  		err = snd_mixer_poll_descriptors(mixer, pfds, 
> > -- 
> > 2.11.0
> > 
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> > 

-- 
David Fries <david at fries.net>