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

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Message-ID: <20180309201957.GA7069@amd>
Date:   Fri, 9 Mar 2018 21:19:57 +0100
From:   Pavel Machek <pavel@....cz>
To:     Mark Brown <broonie@...nel.org>
Cc:     Kees Cook <keescook@...omium.org>, Takashi Iwai <tiwai@...e.com>,
        Liam Girdwood <lgirdwood@...il.com>,
        Jaroslav Kysela <perex@...ex.cz>, alsa-devel@...a-project.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ASoC: soc-core: Add missing NULL check

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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