Date: Mon, 19 Sep 2011 21:21:15 +0300 From: Pekka Enberg <penberg@...helsinki.fi> To: Dave Hansen <dave@...ux.vnet.ibm.com> Cc: Vasiliy Kulikov <segoon@...nwall.com>, Andrew Morton <akpm@...ux-foundation.org>, kernel-hardening@...ts.openwall.com, Kees Cook <kees@...ntu.com>, Cyrill Gorcunov <gorcunov@...il.com>, Al Viro <viro@...iv.linux.org.uk>, Christoph Lameter <cl@...ux-foundation.org>, Matt Mackall <mpm@...enic.com>, linux-kernel@...r.kernel.org, linux-mm@...ck.org, Dan Rosenberg <drosenberg@...curity.com>, Theodore Tso <tytso@....edu>, Alan Cox <alan@...ux.intel.com>, Jesper Juhl <jj@...osbits.net>, Linus Torvalds <torvalds@...ux-foundation.org> Subject: Re: Re: [RFC PATCH 2/2] mm: restrict access to /proc/slabinfo On Mon, 2011-09-19 at 20:51 +0300, Pekka Enberg wrote: >> 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 >> restriction? On Mon, Sep 19, 2011 at 9:03 PM, Dave Hansen <dave@...ux.vnet.ibm.com> wrote: > Mixing it up just adds noise. It makes the attack somewhat more > difficult, but it still leaves open the possibility that the attacker > can filter out the noise somehow. So that would mean the attacker has somewhat fine-grained control over kernel memory allocations, no? Can they use /proc/meminfo to deduce the same kind of information? Should we close that down too? Pekka
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