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From: Florian Weimer <fw@deneb.enyo.de>
To: Daniel Borkmann <dborkman@redhat.com>
Cc: gregkh@linuxfoundation.org, akpm@linux-foundation.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] lib: memcmp_nta: add timing-attack secure memcmp
References: <cover.1360528614.git.dborkman@redhat.com>
	<e73de7873eadcd7a1922535359c46caf25cbf0a2.1360528614.git.dborkman@redhat.com>
Date: Mon, 11 Feb 2013 20:00:54 +0100
In-Reply-To: <e73de7873eadcd7a1922535359c46caf25cbf0a2.1360528614.git.dborkman@redhat.com>
	(Daniel Borkmann's message of "Sun, 10 Feb 2013 23:00:07 +0100")
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* Daniel Borkmann:

> + * memcmp_nta - memcmp that is secure against timing attacks

It's not providing an ordering, so it should not have "cmp" in the
name.

> +	for (su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--)
> +		res |= (*su1 ^ *su2);

The compiler could still short-circuit this loop.  Unlikely at
present, but this looks like a maintenance hazard.