Bug#529326: linux-2.6: CVE-2009-0787 information disclosure in ecryptfs

[dann frazier <dannf@dannf.org>]

On Mon, May 18, 2009 at 02:20:20PM -0400, Michael S. Gilbert wrote:
> On Mon, 18 May 2009 11:52:04 -0600, dann frazier wrote:
> > On Mon, May 18, 2009 at 01:28:56PM -0400, Michael S. Gilbert wrote:
> > > Package: linux-2.6
> > > Version: 2.6.26-15lenny2
> > > Severity: important
> > > Tags: security
> > > 
> > > Hi,
> > > 
> > > The following CVE (Common Vulnerabilities & Exposures) id was
> > > published for linux-2.6.
> > > 
> > > CVE-2009-0787[0]:
> > > | The ecryptfs_write_metadata_to_contents function in the eCryptfs
> > > | functionality in the Linux kernel 2.6.28 before 2.6.28.9 uses an
> > > | incorrect size when writing kernel memory to an eCryptfs file header,
> > > | which triggers an out-of-bounds read and allows local users to obtain
> > > | portions of kernel memory.
> > > 
> > > If you fix the vulnerability please also make sure to include the
> > > CVE id in your changelog entry.
> > > 
> > > For further information see:
> > > 
> > > [0] http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2009-0787
> > >     http://security-tracker.debian.net/tracker/CVE-2009-0787
> > 
> > This issue supposedly only affected 2.6.28 - do you have information
> > to the contrary?
> 
> yes, i have studied the code/patches for this issue.  the 2.6.26
> ecryptfs kernel code is identical to that of the affected 2.6.28 code.
> hence, it is my assessment that 2.6.26 is vulnerable.
> 
> i anticipate that this also affects etch-and-a-half (2.6.24) as well,
> but i have not checked yet.

My understanding is that this issue was introduced by 87b811c (in
2.6.28), which resulted in only a single page getting allocated for
the headers even though the size of the headers maybe > the page size.

-- 
dann frazier