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Date: Thu, 5 Jun 2014 08:49:50 -0700
From: Kees Cook <>
Subject: Re: Linux kernel futex local privilege escalation

On Thu, Jun 05, 2014 at 06:45:45PM +0400, Solar Designer wrote:
> This was handled via linux-distros, hence the mandatory oss-security
> posting.  The issue was made public earlier today, and is included in
> this Debian advisory:
> ---
> CVE-2014-3153
>     Pinkie Pie discovered an issue in the futex subsystem that allows a
>     local user to gain ring 0 control via the futex syscall. An
>     unprivileged user could use this flaw to crash the kernel (resulting
>     in denial of service) or for privilege escalation.

Specifically, the futex syscall can leave a queued kernel waiter hanging
on the stack. By manipulating the stack with further syscalls, the waiter
structure can be altered. When later woken up, the altered waiter can
result in arbitrary code execution in ring 0.

This flaw is especially urgent to fix because futex tends to be
available within most Linux sandboxes (because it is used as a glibc
pthread primitive).


Kees Cook

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