linux-kernel - Re: [GIT PULL] Fix for Integrity subsystem null pointer deref

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Message-ID: <CALCETrUNYRbeA7EiTfd9hXMsHrES9EMAYaS=2FHOO=Kbm6qBTg@mail.gmail.com>
Date:	Wed, 29 Oct 2014 14:22:29 -0700
From:	Andy Lutomirski <luto@...capital.net>
To:	Mimi Zohar <zohar@...ux.vnet.ibm.com>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	LSM List <linux-security-module@...r.kernel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Dan Carpenter <dan.carpenter@...cle.com>,
	James Morris <jmorris@...ei.org>,
	"security@...nel.org" <security@...nel.org>
Subject: Re: [GIT PULL] Fix for Integrity subsystem null pointer deref

On Oct 29, 2014 1:20 PM, "Mimi Zohar" <zohar@...ux.vnet.ibm.com> wrote:
>
> On Wed, 2014-10-29 at 11:51 -0700, Andy Lutomirski wrote:
> > On Wed, Oct 29, 2014 at 11:36 AM, Dan Carpenter
> > <dan.carpenter@...cle.com> wrote:
> > > On Wed, Oct 29, 2014 at 09:23:45AM -0700, Andy Lutomirski wrote:
> > >> I have no idea what the semantics are.  All I'm saying is that it
> > >> looks like the code still accesses memory past the end of the buffer.
> > >> The buffer isn't a null pointer, so the symptom is different, but it
> > >> may still be a security bug.
> > >>
> > >> --Andy
> > >
> > > It only reads one byte into the struct "xattr_data->type" so checking
> > > for non-zero is sufficient and the patch is fine.
> >
> > Indeed.  Still... eww.  I don't like code that, upon local inspection,
> > is apparently wrong, even though it's coincidentally correct due to
> > some other far away condition.
>
> No, the code may be incomplete, but definitely not wrong.

I said "apparently wrong" instead of "wrong" for a reason :)

>
> Mimi
>
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