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From: Pavel Machek <pavel@ucw.cz>
To: "Theodore Y. Ts'o" <tytso@mit.edu>,
	"Lendacky, Thomas" <Thomas.Lendacky@amd.com>,
	nhorman@tuxdriver.com,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-doc@vger.kernel.org" <linux-doc@vger.kernel.org>,
	"linux-pm@vger.kernel.org" <linux-pm@vger.kernel.org>,
	"x86@kernel.org" <x86@kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	"Rafael J . Wysocki" <rjw@rjwysocki.net>,
	Chen Yu <yu.c.chen@intel.com>, Jonathan Corbet <corbet@lwn.net>
Subject: Re: Non-random RDRAND Re: [PATCH] x86/CPU/AMD: Clear RDRAND CPUID bit on AMD family 15h/16h
Date: Fri, 16 Aug 2019 11:07:13 +0200
Message-ID: <20190816090713.GA17833@amd> (raw)
In-Reply-To: <20190815151224.GB18727@mit.edu>

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On Thu 2019-08-15 11:12:24, Theodore Y. Ts'o wrote:
> On Thu, Aug 15, 2019 at 01:24:35AM +0200, Pavel Machek wrote:
> > Burn it with fire!
> > 
> > I mean... people were afraid RDRAND would be backdoored, and you now
> > confirm ... it indeed _is_ backdoored? /., here's news for you!
> 
> To be fair to AMD, I wouldn't call it a backdoor.  Hanlon's razor is
> applicable here:
> 
> 	"Never attribute to malice that which can be adequately
> 	explained by neglect."

> (Sometimes other words are used instead of neglect, but i'm trying to
> be nice.)

You are right, I thought it was returning values with low entropy, and
it returns ~0 (so -- really really low entropy :-) and can't be
clasified as a backdoor.

Anyway, AMD is _not_ doing good job right now.

I'd expect:

a) CVE reference

b) real fix; if BIOS can init the rng, so can kernel

									Pavel

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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  reply index

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-14 21:17 Lendacky, Thomas
2019-08-14 23:24 ` Non-random RDRAND " Pavel Machek
2019-08-14 23:38   ` Pavel Machek
2019-08-15 13:01   ` Lendacky, Thomas
2019-08-15 15:12   ` Theodore Y. Ts'o
2019-08-16  9:07     ` Pavel Machek [this message]
2019-08-16 14:42     ` Neil Horman
2019-08-15  7:21 ` Borislav Petkov
2019-08-15 13:47   ` Lendacky, Thomas
2019-08-15 15:34     ` Borislav Petkov
2019-08-15 20:14       ` Thomas Gleixner
2019-08-15 20:59 ` Andrew Cooper
2019-08-15 21:04   ` Thomas Gleixner
2019-08-15 21:05   ` Borislav Petkov
2019-08-15 21:25     ` Andrew Cooper
2019-08-17  8:44       ` Borislav Petkov
2019-08-17 11:43         ` Andrew Cooper
2019-08-18 16:32           ` Thomas Gleixner
2019-08-16 15:19 ` Andy Lutomirski

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