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Date: Wed, 14 Sep 2011 12:27:44 -0700
From: Kees Cook <>
To: Vasiliy Kulikov <>
        Andrew Morton <>,
        Cyrill Gorcunov <>,
        Al Viro <>,
        Christoph Lameter <>,
        Pekka Enberg <>, Matt Mackall <>,,
Subject: Re: [RFC PATCH 2/2] mm: restrict access to /proc/slabinfo

Hi Vasiliy,

On Sat, Sep 10, 2011 at 08:41:34PM +0400, Vasiliy Kulikov wrote:
> Historically /proc/slabinfo has 0444 permissions and is accessible to
> the world.  slabinfo contains rather private information related both to
> the kernel and userspace tasks.  Depending on the situation, it might
> reveal either private information per se or information useful to make
> another targeted attack.  Some examples of what can be learned by
> reading/watching for /proc/slabinfo entries:
> ...
> World readable slabinfo simplifies kernel developers' job of debugging
> kernel bugs (e.g. memleaks), but I believe it does more harm than
> benefits.  For most users 0444 slabinfo is an unreasonable attack vector.
> Signed-off-by: Vasiliy Kulikov <>

Haven't had any mass complaints about the 0400 in Ubuntu (sorry Dave!), so
I'm obviously for it.

Reviewed-by: Kees Cook <>


Kees Cook
Ubuntu Security Team

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