linux-kernel - Re: DRAM unreliable under specific access patern

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Date:	Mon, 9 Mar 2015 09:03:18 -0700
From:	Mark Seaborn <mseaborn@...omium.org>
To:	Pavel Machek <pavel@....cz>,
	kernel list <linux-kernel@...r.kernel.org>
Cc:	One Thousand Gnomes <gnomes@...rguk.ukuu.org.uk>,
	luto <luto@...capital.net>
Subject: Re: DRAM unreliable under specific access patern

On 6 January 2015 at 15:20, Pavel Machek <pavel@....cz> wrote:
> On Mon 2015-01-05 19:23:29, One Thousand Gnomes wrote:
> > > In the meantime, I created test that actually uses physical memory,
> > > 8MB apart, as described in some footnote. It is attached. It should
> > > work, but it needs boot with specific config options and specific
> > > kernel parameters.
> >
> > Why not just use hugepages. You know the alignment guarantees for 1GB
> > pages and that means you don't even need to be root
> >
> > In fact - should we be disabling 1GB huge page support by default at this
> > point, at least on non ECC boxes ?
>
> Actually, I could not get my test code to run; and as code from
>
> https://github.com/mseaborn/rowhammer-test
>
> reproduces issue for me, I stopped trying. I could not get it to
> damage memory of other process than itself (but that should be
> possible), I guess that's next thing to try.

FYI, rowhammer-induced bit flips do turn out to be exploitable.  Here
are the results of my research on this:
http://googleprojectzero.blogspot.com/2015/03/exploiting-dram-rowhammer-bug-to-gain.html

Cheers,
Mark
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