full-disclosure - Re: [FD] [oss-security] CVE-2014-0196: Linux kernel pty layer race condition memory corruption

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Message-ID: <CAD3CanfQNXvv3jVN9Cu6ySusTKbmNXhxnpj2oXCoJF5-3JYv1w@mail.gmail.com>
Date: Mon, 12 May 2014 21:15:10 +1200
From: Matthew Daley <mattd@...fuzz.com>
To: oss-security@...ts.openwall.com
Cc: fulldisclosure@...lists.org, bugtraq@...urityfocus.com
Subject: Re: [FD] [oss-security] CVE-2014-0196: Linux kernel pty layer race
 condition memory corruption

Hi,

I've written a "slightly-less-than-POC" privilege escalation exploit for
this vulnerability that works on newer kernels:
http://bugfuzz.com/stuff/cve-2014-0196-md.c (SHA1:
6b1c5c651231b33a5e11b5c8c6ed07cd15f658f5)

Note the warning mentioned in the header; run it at your own risk ;)

- Matthew Daley

On Mon, May 5, 2014 at 10:08 PM, Marcus Meissner <meissner@...e.de> wrote:

> Hi,
>
> SUSE customer Ericsson reported a kernel crash to us which turned out
> to be a race condition in the PTY write buffer handling.
>
> When two processes/threads write to the same pty, the buffer end could
> be overwritten and so memory corruption into adjacent buffers could lead
> to crashes / code execution.
>
> Jiri Slaby and Peter Hurley localized and fixed this problem.
>
> CVE-2014-0196 has been assigned to this issue.
>
> Jiri thinks this was introduced during 2.6.31 development by
> d945cb9cce20ac7143c2de8d88b187f62db99bdc (pty: Rework the pty
> layer to use the normal buffering logic) in 2.6.31-rc3. Until then, pty
> was writing directly to a line discipline without using buffers.
>
> https://bugzilla.novell.com/show_bug.cgi?id=875690
>
> Patch is also attached.
>
> Ciao, Marcus
>

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