On Fri, Mar 09, 2018 at 10:45:16AM -0800, Kees Cook wrote: > On Fri, Mar 9, 2018 at 4:50 AM, Mark Brown <broonie@xxxxxxxxxx> 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"? > SoC's sound component? I'm not sure either. :) I was just sending the > patch that I mentioned from the thread where Pavel mentioned this > Oops. Oh, Pavel's thing. I didn't look at that yet. I'm afraid your description still isn't making much sense to me - I'm guessing that you're just papering over an immediate crack rather than having analyized the situation in any depth? > >> + 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. > No idea! Hopefully Pavel has more details... That's where the fix should be, it implies that there's some larger data corruption/confusion problem somewhere else. If we've created the file but left a NULL pointer I'd expect that there is a good chance that there'll be other things that think we've got a CODEC and try to defererence the pointer, it's an assumption that's present throughout the code. I think I might just remove the file though, it's been non-functional on most systems for a while now as almost all the drivers migrated to regmap and nobody complained so we should be safe. There's still something that ought to be investigated here.
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