From: Pavel Machek <pavel@ucw.cz>
To: "Lendacky, Thomas" <Thomas.Lendacky@amd.com>,
tytso@mit.edu, nhorman@tuxdriver.com, security@kernel.org
Cc: "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: Thu, 15 Aug 2019 01:38:49 +0200 [thread overview]
Message-ID: <20190814233849.GA462@amd> (raw)
In-Reply-To: <20190814232434.GA31769@amd>
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On Thu 2019-08-15 01:24:35, Pavel Machek wrote:
> On Wed 2019-08-14 21:17:41, Lendacky, Thomas wrote:
> > From: Tom Lendacky <thomas.lendacky@amd.com>
> >
> > There have been reports of RDRAND issues after resuming from suspend on
> > some AMD family 15h and family 16h systems. This issue stems from BIOS
> > not performing the proper steps during resume to ensure RDRAND continues
> > to function properly.
>
> 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!
>
> So what is the impact? Does it give random-looking but predictable
> numbers after resume? Does it give all zeros? Something else?
Plus... We trust the RDRAND in some configurations:
random.trust_cpu={on,off}
[KNL] Enable or disable trusting the
use of the CPU's random
number generator (if available) to
fully seed the
kernel's CRNG. Default is controlled by
CONFIG_RANDOM_TRUST_CPU.
so.. does this mean /dev/random was giving non-random values for some
users?
Certainly it means userland users were getting non-random values. That
sounds like something worth CVE and informing affected users?
Best regards,
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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next prev parent reply other threads:[~2019-08-14 23:38 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-14 21:17 [PATCH] x86/CPU/AMD: Clear RDRAND CPUID bit on AMD family 15h/16h Lendacky, Thomas
2019-08-14 23:24 ` Non-random RDRAND " Pavel Machek
2019-08-14 23:38 ` Pavel Machek [this message]
2019-08-15 13:01 ` Lendacky, Thomas
2019-08-15 15:12 ` Theodore Y. Ts'o
2019-08-16 9:07 ` Pavel Machek
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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