mixer: Fix memory leak for more than 16 file descriptor case
diff mbox series

Message ID 20200106214129.fnrokzkh4qnbvzdl@spacedout.fries.net
State New
Headers show
Series
  • mixer: Fix memory leak for more than 16 file descriptor case
Related show

Commit Message

David Fries Jan. 6, 2020, 9:41 p.m. UTC
---
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.

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(-)

Comments

Takashi Iwai Jan. 7, 2020, 1:03 p.m. UTC | #1
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
> 
> _______________________________________________
> Alsa-devel mailing list
> Alsa-devel@alsa-project.org
> https://mailman.alsa-project.org/mailman/listinfo/alsa-devel
>
David Fries Jan. 7, 2020, 3:18 p.m. UTC | #2
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
> > 
> > _______________________________________________
> > Alsa-devel mailing list
> > Alsa-devel@alsa-project.org
> > https://mailman.alsa-project.org/mailman/listinfo/alsa-devel
> >

Patch
diff mbox series

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,