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

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Message-ID: <1414614013.5330.90.camel@dhcp-9-2-203-236.watson.ibm.com>
Date:	Wed, 29 Oct 2014 16:20:13 -0400
From:	Mimi Zohar <zohar@...ux.vnet.ibm.com>
To:	Andy Lutomirski <luto@...capital.net>
Cc:	Dan Carpenter <dan.carpenter@...cle.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	LSM List <linux-security-module@...r.kernel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	"security@...nel.org" <security@...nel.org>,
	James Morris <jmorris@...ei.org>
Subject: Re: [GIT PULL] Fix for Integrity subsystem null pointer deref

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.

Mimi

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