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Date: Tue, 24 May 2016 23:23:24 +0200
From: Emese Revfy <re.emese@gmail.com>
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Subject: [kernel-hardening] Re: [PATCH v1 1/3] Add the latent_entropy gcc plugin
To: Kees Cook <keescook@chromium.org>
Cc: "kernel-hardening@lists.openwall.com" <kernel-hardening@lists.openwall.com>, PaX Team <pageexec@freemail.hu>, Brad Spengler <spender@grsecurity.net>, Michal Marek <mmarek@suse.com>, LKML <linux-kernel@vger.kernel.org>, Masahiro Yamada <yamada.masahiro@socionext.com>, linux-kbuild <linux-kbuild@vger.kernel.org>, Theodore Ts'o <tytso@mit.edu>, Andrew Morton <akpm@linux-foundation.org>, Linux-MM <linux-mm@kvack.org>, Jens Axboe <axboe@kernel.dk>, Al Viro <viro@zeniv.linux.org.uk>, Paul McKenney <paulmck@linux.vnet.ibm.com>, Ingo Molnar <mingo@redhat.com>, Thomas Gleixner <tglx@linutronix.de>, bart.vanassche@sandisk.com, "David S. Miller" <davem@davemloft.net>
List-ID: <kernel-hardening.lists.openwall.com>

On Tue, 24 May 2016 10:32:15 -0700
Kees Cook <keescook@chromium.org> wrote:

> Also, does this matter that it's non-atomic? It seems like the u64
> below is being written to by multiple threads and even read by
> multiple threads. Am I misunderstanding something?

The non-atomic accesses are intentional because
they can extract more latent entropy from these data races.
 
> > [...]
> > new file mode 100644
> > index 0000000..7295c39
> > --- /dev/null
> > +++ b/scripts/gcc-plugins/latent_entropy_plugin.c
> 
> I feel like most of the functions in this plugin could use some more
> comments about what each one does.

I think the important parts are commented (most parts just use the gcc API).
Where would you like more comments?

-- 
Emese