From: Herbert Xu <herbert@gondor.apana.org.au>
To: Giel van Schijndel <me@mortis.eu>
Cc: linux-kernel@vger.kernel.org,
"David S. Miller" <davem@davemloft.net>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
"maintainer:X86 ARCHITECTURE..." <x86@kernel.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Steve French <sfrench@samba.org>,
Rahul Bedarkar <rahulbedarkar89@gmail.com>,
Thomas Pugliese <thomas.pugliese@gmail.com>,
Randy Dunlap <rdunlap@infradead.org>,
Julia Lawall <Julia.Lawall@lip6.fr>,
"open list:CRYPTO API" <linux-crypto@vger.kernel.org>,
"open list:CERTIFIED WIRELES..." <linux-usb@vger.kernel.org>,
"open list:COMMON INTERNET F..." <linux-cifs@vger.kernel.org>,
"moderated list:COMMON INTERNET F..."
<samba-technical@lists.samba.org>,
Daniel Borkmann <dborkman@redhat.com>
Subject: Re: [PATCH] Use memzero_explicit to clear local buffers
Date: Mon, 5 Jan 2015 10:36:37 +1100 [thread overview]
Message-ID: <20150104233637.GA20757@gondor.apana.org.au> (raw)
In-Reply-To: <20150104224909.GB4806@salidar.dom.custoft.eu>
On Sun, Jan 04, 2015 at 11:49:09PM +0100, Giel van Schijndel wrote:
>
> > sctx does not point to stack memory so this is bogus.
> >
> > Only stack memory cleared just before it goes out of scope needs
> > memzero_explicit.
>
> Is that because the compiler can't safely optimize memset(0) away for a
> variable with greater-than-local scope?
Exactly. memzero_explicit is not a marker for sensitive data.
Its only purpose is to prevent the compiler from optimising away
zeroing that occurs at the end of a scope.
Daniel, we should add a comment so that people stop sending bogus
patches with memzero_explicit.
Cheers,
--
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
next prev parent reply other threads:[~2015-01-04 23:37 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-01-04 18:05 Giel van Schijndel
2015-01-04 21:35 ` Herbert Xu
2015-01-04 22:49 ` Giel van Schijndel
2015-01-04 23:36 ` Herbert Xu [this message]
2015-01-06 19:42 ` Giel van Schijndel
2015-01-06 20:54 ` Herbert Xu
2015-01-04 23:05 ` Giel van Schijndel
2015-01-06 21:37 ` [PATCH RESEND] cifs: use memzero_explicit to clear stack buffer Giel van Schijndel
2015-01-06 22:59 ` Herbert Xu
2015-01-13 0:12 ` Steve French
2015-01-09 18:53 ` Steve French
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