From: Hannes Frederic Sowa <hannes@stressinduktion.org>
Subject: Re: [BUG/PATCH] kernel RNG and its secrets
Date: Wed, 18 Mar 2015 18:56:19 +0100
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Cc: Daniel Borkmann <daniel@iogearbox.net>,
	Stephan Mueller <smueller@chronox.de>,
	mancha <mancha1@zoho.com>, linux-kernel@vger.kernel.org,
	linux-crypto@vger.kernel.org, herbert@gondor.apana.org.au,
	dborkman@redhat.com
To: "Theodore Ts'o" <tytso@mit.edu>
In-Reply-To: <20150318174136.GD5663@thunk.org>
Sender: linux-crypto-owner@vger.kernel.org

On Wed, Mar 18, 2015, at 18:41, Theodore Ts'o wrote:
> Maybe we should add a kernel self-test that automatically checks
> whether or not memset_explicit() gets optimized away?  Otherwise we
> might not notice when gcc or how we implement barrier() or whatever
> else we end up using ends up changing.
> 
> It shold be something that is really fast, so it might be a good idea
> to simply automatically run it as part of an __initcall()
> unconditionally.  We can debate where the __initcall() lives, but I'd
> prefer that it be run even if the crypto layer isn't configured for
> some reason.  Hopefully such an self-test is small enough that the
> kernel bloat people won't complain.  :-)
> 
> 							 -Ted

Maybe a BUILD_BUGON: ;)

__label__ l1, l2;
char buffer[1024];
l1:
    memset(buffer, 0, 1024);
l2:
  BUILD_BUGON(&&l1 == &&l2);