[PATCH] sound: hdmi: avoid dereferencing uninitialized 'jack' pointer

Takashi Iwai
2016-02-16T17:10:02Z

On Tue, 16 Feb 2016 17:59:04 +0100,
Arnd Bergmann wrote:
>
> On Tuesday 16 February 2016 16:38:40 Mark Brown wrote:
> > On Tue, Feb 16, 2016 at 05:18:29PM +0100, Takashi Iwai wrote:
> > > Arnd Bergmann wrote:
> >
> > > > Another option might would be to change snd_jack_new() to return
> > > > an error if that SND_JACK is disabled, and then require all users
> > > > to handle the error gracefully, i.e. not fail the probe() function
> > > > but just not use the jack.
> >
> > > Yes, I thought of that, too. If select is no good option, it's a good
> > > alternative, indeed.
> >
> > It's going to be a bunch of work to implement though.
> >
>
> I've already sent a v2 to change the snd_jack_new() function, feel free
> to ignore that. I also saw now that the same bug is present in hda_jack.c,
> but I think the other drivers are fine.
>
> How about this approach below? That should also make it possible to
> use the jack APIs without using a error return.

I prefer setting NULL explicitly in snd_jack_new(), and let callers
checking NULL. Then we can avoid ugly IS_ENABLE() while the compiler
should be still capable to optimize out.

OTOH, I think it'd be a waste of time to bikeshedding too much, so I
don't care so much which to take :)

Takashi

---
diff --git a/include/sound/jack.h b/include/sound/jack.h
index 23bede121c78..a27c253a3207 100644
--- a/include/sound/jack.h
+++ b/include/sound/jack.h
@@ -99,6 +99,7 @@ void snd_jack_report(struct snd_jack *jack, int status);
static inline int snd_jack_new(struct snd_card *card, const char *id, int type,
struct snd_jack **jack, bool initial_kctl, bool phantom_jack)
{
+ *jack = NULL;
return 0;
}

diff --git a/sound/pci/hda/hda_jack.c b/sound/pci/hda/hda_jack.c
index a33234e04d4f..babd3a8864a1 100644
--- a/sound/pci/hda/hda_jack.c
+++ b/sound/pci/hda/hda_jack.c
@@ -403,10 +403,12 @@ int snd_hda_jack_add_kctl(struct hda_codec *codec, hda_nid_t nid,

jack->phantom_jack = !!phantom_jack;
jack->type = type;
- jack->jack->private_data = jack;
- jack->jack->private_free = hda_free_jack_priv;
- state = snd_hda_jack_detect(codec, nid);
- snd_jack_report(jack->jack, state ? jack->type : 0);
+ if (jack->jack) {
+ jack->jack->private_data = jack;
+ jack->jack->private_free = hda_free_jack_priv;
+ state = snd_hda_jack_detect(codec, nid);
+ snd_jack_report(jack->jack, state ? jack->type : 0);
+ }

return 0;
}
diff --git a/sound/pci/hda/patch_hdmi.c b/sound/pci/hda/patch_hdmi.c
index 8ee78dbd4c60..34a7b3aaba11 100644
--- a/sound/pci/hda/patch_hdmi.c
+++ b/sound/pci/hda/patch_hdmi.c
@@ -2158,8 +2158,10 @@ static int add_acomp_jack_kctl(struct hda_codec *codec,
if (err < 0)
return err;
per_pin->acomp_jack = jack;
- jack->private_data = per_pin;
- jack->private_free = free_acomp_jack_priv;
+ if (jack) {
+ jack->private_data = per_pin;
+ jack->private_free = free_acomp_jack_priv;
+ }
return 0;
}