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Message-ID: <alpine.DEB.2.20.1512221023550.2748@east.gentwo.org>
Date: Tue, 22 Dec 2015 10:25:00 -0600 (CST)
From: Christoph Lameter <cl@...ux.com>
To: Dave Hansen <dave.hansen@...el.com>
cc: kernel-hardening@...ts.openwall.com, Pekka Enberg <penberg@...nel.org>,
David Rientjes <rientjes@...gle.com>, Joonsoo Kim <iamjoonsoo.kim@....com>,
Andrew Morton <akpm@...ux-foundation.org>,
Laura Abbott <laura@...bott.name>, linux-mm@...ck.org,
linux-kernel@...r.kernel.org, Kees Cook <keescook@...omium.org>
Subject: Re: [RFC][PATCH 6/7] mm: Add Kconfig option for
slab sanitization
On Tue, 22 Dec 2015, Dave Hansen wrote:
> On 12/21/2015 07:40 PM, Laura Abbott wrote:
> > + The tradeoff is performance impact. The noticible impact can vary
> > + and you are advised to test this feature on your expected workload
> > + before deploying it
>
> What if instead of writing SLAB_MEMORY_SANITIZE_VALUE, we wrote 0's?
> That still destroys the information, but it has the positive effect of
> allowing a kzalloc() call to avoid zeroing the slab object. It might
> mitigate some of the performance impact.
We already write zeros in many cases or the object is initialized in a
different. No one really wants an uninitialized object. The problem may be
that a freed object is having its old content until reused. Which is
something that poisoning deals with.
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