Re: [PATCH] ASoC: soc-core: Add missing NULL check

From: Pavel Machek
Date: Fri Mar 09 2018 - 15:20:06 EST


On Fri 2018-03-09 12:50:50, Mark Brown wrote:
> On Thu, Mar 08, 2018 at 12:06:53PM -0800, Kees Cook wrote:
>
> > If a codec is not attached to the sound soc, a NULL deref is possible as a
> > regular user in /sys.
>
> I can't parse this, sorry. What is the "sound soc"?
>
> > +++ b/sound/soc/soc-core.c
> > @@ -137,6 +137,9 @@ static ssize_t soc_codec_reg_show(struct snd_soc_codec *codec, char *buf,
> > size_t total = 0;
> > loff_t p = 0;
> >
> > + if (!codec || !codec->driver)
> > + return 0;
> > +
>
> How are we managing to create a sysfs file for a CODEC which doesn't
> have a CODEC struct associated with it? That is obviously nonsensical
> and suggests we've got some more serious problem going on here - if
> there's no CODEC those sysfs attributes simply shouldn't be there.

Look for "linux-next on n900: oops in codec_reg_show() when grepping
sysfs" ... should be in your inbox.
Pavel

--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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