oss-security - Re: CVE request: kernel: tc: uninitialised kernel memory leak

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Date: Wed, 16 Sep 2009 21:19:02 -0400 (EDT)
From: "Steven M. Christey" <coley@...us.mitre.org>
To: oss-security@...ts.openwall.com
cc: Willy Tarreau <w@....eu>, Eugene Teo <eugene@...hat.com>,
        "Steven M. Christey" <coley@...us.mitre.org>
Subject: Re: CVE request: kernel: tc: uninitialised kernel
 memory leak

On Sat, 5 Sep 2009, Solar Designer wrote:

> On Thu, Sep 03, 2009 at 11:45:03AM +0800, Eugene Teo wrote:
> > Three bytes of uninitialised kernel memory are currently leaked to user.
> >
> > http://patchwork.ozlabs.org/patch/32830/
> > https://bugzilla.redhat.com/show_bug.cgi?id=520990
>
> 2.4 kernels appear to be affected as well, and moreover they appear to
> require at least some of these older fixes as well:
>
> http://marc.info/?l=git-commits-head&m=112002138324380
>
> Specifically, in net/sched/sch_api.c both tc_fill_qdisc() and
> tc_fill_tclass() are affected - the former was fixed in 2.6 in 2005,
> the latter is being fixed now.
>
> I'm not sure what this means for CVE.  Should there be another CVE id
> for the issues fixed in 2.6 in 2005 (if one was not allocated at the
> time), and 2.4 could reference both CVE ids now?

This would be the typical practice.  We weren't tracking kernel bugs at
the function-name level back then, though - we were using more mature (and
more general) advisory descriptions - so I can't be absolutely sure
whether there's a CVE for this or not.

However, a search for "netlink" turned up empty for this type of problem
in that time frame, so we probably don't have a CVE for it yet.

One question, though - http://patchwork.ozlabs.org/patch/32830/ patches
net/sched/sch_api.c / tc_fill_tclass, but the 2005 patch includes
net/core/neighbour.c, net/sched/cls_api.c, and others.

So we have:

tc_fill_qdisc() - already fixed in 2.6; just fixed in 2.4

  http://marc.info/?l=git-commits-head&m=112002138324380
  (not sure of reference for 2.4)

multiple functions e.g. tcf_fill_node() already fixed in 2.6; unknown
status in 2.4.  Includes neightbl_fill_info(), neightbl_fill_param_info(),
and others.

  http://marc.info/?l=git-commits-head&m=112002138324380

tc_fill_tclass() - just fixed in 2.6

  http://patchwork.ozlabs.org/patch/32830/

So for now, we have:

  CVE-2009-3228 - tc_fill_tclass()

  CVE-2005-4881 - tc_fill_qdisc()  (at least)

Now we have:

  tcf_fill_node(), neightbl_fill_info(), and others from 2005.

Typical practice would be to associate tcf_fill_node() and the others with
CVE-2005-4881, not just have it be with tc_fill_qdisc() - because they
were all disclosed in 2005.  Then the 2.4 fix might only apply to a
portion of CVE-2005-4881.  This could make it difficult to coordinate
low-level patches, but our "(1)" and "(2)" numbering style in the CVE
description could be used at that level if needed.

So, let's go with these two numbers.  I'll fill them out later.  (My head
hurts.)

Oh, and if anybody could give me more precise version information than
"2.4" and "2.6" then that would be appreciated.

- Steve

P.S. I chose the 2005 date in the CVE to help with distinguishing the
problems, but arguably this should have received a 2009, because the 2005
fix was so vague that the security implications weren't (apparently) known
until 2009.

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