From: Mikael Pettersson <mikpe@it.uu.se>
To: Brian Gerst <brgerst@gmail.com>
Cc: Mikael Pettersson <mikpe@it.uu.se>,
Roel Kluin <roel.kluin@gmail.com>,
Herbert Xu <herbert@gondor.apana.org.au>,
"David S. Miller" <davem@davemloft.net>,
linux-crypto@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] sha: prevent removal of memset as dead store in sha1_update()
Date: Thu, 25 Feb 2010 18:09:36 +0100 [thread overview]
Message-ID: <19334.44752.357207.382349@pilspetsen.it.uu.se> (raw)
In-Reply-To: <73c1f2161002250833n120cda05s9371e5ce13cc0aac@mail.gmail.com>
Brian Gerst wrote:
> Would barrier() (which is a simple memory clobber) after the memset work?
I don't know. It's implemented as an asm with a "memory" clobber,
but I wouldn't bet on that forcing previous writes to a dying object
to actally be performed (it would have to have a data-dependency on
the dying object, but I don't think there is one).
void secure_bzero(void *p, size_t n)
{
memset(p, 0, n);
asm("" : : "m"(*(char*)p));
}
seems to work, but as the object in general will be larger than a
single byte, I'd like to see some confirmation from the gcc folks
first that this will in fact work.
next prev parent reply other threads:[~2010-02-25 17:09 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-02-25 15:10 Roel Kluin
2010-02-25 15:17 ` David Miller
2010-02-25 15:31 ` roel kluin
2010-02-25 15:37 ` David Miller
2010-02-26 11:55 ` Andi Kleen
2010-02-26 14:20 ` Mikael Pettersson
2010-02-26 15:46 ` Mikael Pettersson
2010-02-26 15:55 ` Andi Kleen
2010-02-25 15:56 ` Mikael Pettersson
2010-02-25 16:16 ` Pekka Enberg
2010-02-25 16:29 ` Mikael Pettersson
2010-02-25 16:33 ` roel kluin
2010-02-25 17:06 ` roel kluin
2010-02-25 16:33 ` Brian Gerst
2010-02-25 17:09 ` Mikael Pettersson [this message]
2010-02-25 17:32 ` Brian Gerst
2010-02-25 19:47 ` Roel Kluin
2010-02-25 20:43 ` Roel Kluin
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