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From: mark gross <mgross@linux.intel.com>
To: speck@linutronix.de
Subject: [MODERATED] Re: [PATCH 0/2] more sampling fun 0
Date: Thu, 20 Feb 2020 07:40:07 -0800	[thread overview]
Message-ID: <20200220154007.GC58564@mtg-dev.jf.intel.com> (raw)
In-Reply-To: <20200220142720.GA3433900@kroah.com>

On Thu, Feb 20, 2020 at 03:27:20PM +0100, speck for Greg KH wrote:
> On Thu, Feb 20, 2020 at 09:14:20AM +0100, speck for Greg KH wrote:
> > On Wed, Feb 19, 2020 at 02:45:22PM -0800, speck for mark gross wrote:
> > > From: mark gross <mgross@linux.intel.com>
> > > Subject: [PATCH 0/2] Special Register Buffer Data Sampling patch set 
> > > 
> > > Special Register Buffer Data Sampling is a sampling type of vulnerability that
> > > leaks data across cores sharing the HW-RNG for vulnerable processors.
> > > 
> > > This leak is fixed by a microcode update and is enabled by default.
> > > 
> > > This new microcode serializes processor access during execution of RDRAND
> > > or RDSEED. It ensures that the shared buffer is overwritten before it
> > > is released for reuse.
> > > 
> > > The mitigation impacts the throughput of the RDRAND and RDSEED instructions
> > > and latency of RT processing running on the socket while executing RDRAND or
> > > RDSEED.  The micro bechmark of calling RDRAND many times shows a 10x slowdown.
> > 
> > Then we need to stop using RDRAND internally for our "give me a random
> > number api" which has spread to more and more parts of the kernel.
> > 
> > Here's a patch that does so:
> > 	https://lore.kernel.org/lkml/20200216161836.1976-1-Jason@zx2c4.com/
> > which I'm going to advise get merged now and backported to the stable
> > branches.
> 
> Note, the author of that patch has reached out to me to say they found
> this same issue.  He did so independantly so odds are others already
> know about this.  He found it because he was wondering why rdrand was so
> slow on newer systems, and then traced things backwards like all the
> other researchers in this area.
Are you saying the author has seen the RNG data leaking across processors or
the slowdown?

> 
> So, what's the timeline here?  Looks like this is already "in the wild"
> from what I can tell.
>
The uCode mitigation is coming out with the 2020.1 IPU (intel platform update)
(fist ucode update of 2020) that I belive is slated for an official May
disclosure.

--mark

 
> greg k-h

  reply	other threads:[~2020-02-20 15:40 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-19 22:45 [MODERATED] " mark gross
2020-02-20  1:53 ` [MODERATED] " mark gross
2020-02-20  8:14 ` Greg KH
2020-02-20 14:27   ` Greg KH
2020-02-20 15:40     ` mark gross [this message]
2020-02-20 16:18       ` Greg KH
2020-02-20 14:55   ` Andi Kleen
2020-02-20 15:05     ` Greg KH
2020-02-20 16:55       ` Andi Kleen
2020-02-20 21:51     ` Josh Poimboeuf
2020-02-20 22:15       ` Andi Kleen
2020-02-20 22:59         ` Kees Cook
2020-02-20 15:09   ` mark gross
2020-02-28 16:21   ` [MODERATED] Additional sampling fun Borislav Petkov
2020-02-28 16:34     ` [MODERATED] " Greg KH
2020-02-28 17:38       ` mark gross
2020-02-28 17:44         ` Thomas Gleixner
2020-02-28 18:09           ` [MODERATED] " Luck, Tony
2020-02-28 18:40             ` Borislav Petkov
2020-02-28 21:53             ` Thomas Gleixner
2020-03-03  1:03               ` [MODERATED] " Luck, Tony

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