Follow @Openwall on Twitter for new release announcements and other news
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date: Fri, 20 Jan 2017 21:39:41 +1100
From: Harshula <>
To:, Greg KH <>
Cc: Jesse Hertz <>,
        Wade Mealing
Subject: Re: CVE REQUEST: linux kernel: process with pgid
 zero able to crash kernel

Hi Greg,

On Fri, 2017-01-20 at 09:26 +0100, Greg KH wrote:
> On Fri, Jan 20, 2017 at 01:41:52PM +1100, Harshula wrote:
> > Hi Folks,
> > 
> > Red Hat Product Security has been notified of a kernel vulnerability
> > that a local attacker can exploit to crash/panic the kernel and cause a
> > denial of service.
> > 
> > This was reported to Red Hat by Jesse Hertz (CC'd) (reproducer:
> > rt411016):
> > 
> > "A process that is in the same process group as the ``init'' process
> > (group id zero) can crash the Linux 2 kernel with several system calls
> > by passing in a process ID or process group ID of zero. The value zero
> > is a special value that indicates the current process ID or process
> > group. However, in this case it is also the process group ID of the
> > process."
> > 
> > I've been testing whether RHEL is vulnerable and found the following:
> > 
> > * Upstream/mainline is not vulnerable
> Is this true for the mainline kernel tree that RHEL 6 was based on?
> > * RHEL 7 is not vulnerable
> > * RHEL 6 is vulnerable
> > * RHEL 5 is partially vulnerable
> So this is only due to a specific set of patches that were added to RHEL
> 6 and RHEL 5 yet never made it upstream?  I ask as we want to make sure
> some of the older LTS mainline kernels might be affected and it would be
> good to ensure they are not.

Good questions, I had not looked at it from a mainline timeline

1) Mainline kernels containing patches [a], [b] and [c] are not

2) The vulnerability is *NOT* due to non-upstream patches that went
into RHEL 5 and/or 6.

3) I suspect some older LTS mainline kernels that branched off
mainline/upstream at around the same time as RHEL 6 would be
vulnerable. Check if the data structure fields, corresponding to the
initialization changes in patch [a], [b] and [c], are initialized the
same way in the LTS mainline kernels you maintain.

4) For any RHEL 5 vintage LTS mainline kernels, see if task_struct's
thread_group field is not initialised. If so, it is likely partially
vulnerable and could do with a strong dose of patch [c].





Powered by blists - more mailing lists

Please check out the Open Source Software Security Wiki, which is counterpart to this mailing list.

Confused about mailing lists and their use? Read about mailing lists on Wikipedia and check out these guidelines on proper formatting of your messages.