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Date: Mon, 19 Sep 2011 20:51:59 +0300
From: Pekka Enberg <>
To: Vasiliy Kulikov <>
Cc: Andrew Morton <>,, 
	Kees Cook <>, Cyrill Gorcunov <>, Al Viro <>, 
	Christoph Lameter <>, Matt Mackall <>,,, Dan Rosenberg <>, Theodore Tso <>, 
	Alan Cox <>, Jesper Juhl <>, 
	Linus Torvalds <>
Subject: Re: Re: [RFC PATCH 2/2] mm: restrict access to /proc/slabinfo

On Mon, Sep 19, 2011 at 8:35 PM, Vasiliy Kulikov <> wrote:
>> Yes, but there's no way for users to know where the allocations came from
>> if you mix them up with other kmalloc-128 call-sites. That way the number
>> of private files will stay private to the user, no? Doesn't that give you even
>> better protection against the infoleak?
> No, what it gives us is an obscurity, not a protection.  I'm sure it
> highly depends on the specific situation whether an attacker is able to
> identify whether the call is from e.g. ecryptfs or from VFS.  Also the
> correlation between the number in slabinfo and the real private actions
> still exists.

How is the attacker able to identify that we kmalloc()'d from ecryptfs or
VFS based on non-root /proc/slabinfo when the slab allocator itself does
not have that sort of information if you mix up the allocations? Isn't this
much stronger protection especially if you combine that with /proc/slabinfo


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