Re: [Security] [PATCH] proc: avoid information leaks to non-privileged processes

From: Linus Torvalds <torvalds@linux-foundation.org>
To: Matt Mackall <mpm@selenic.com>
Cc: Ingo Molnar <mingo@elte.hu>,
	"Eric W. Biederman" <ebiederm@xmission.com>,
	Arjan van de Ven <arjan@infradead.org>, Jake Edge <jake@lwn.net>,
	security@kernel.org,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	James Morris <jmorris@namei.org>,
	linux-security-module@vger.kernel.org,
	Eric Paris <eparis@redhat.com>,
	Alan Cox <alan@lxorguk.ukuu.org.uk>,
	Roland McGrath <roland@redhat.com>,
	mingo@redhat.com, Andrew Morton <akpm@linux-foundation.org>,
	Greg KH <greg@kroah.com>, Dave Jones <davej@redhat.com>
Subject: Re: [Security] [PATCH] proc: avoid information leaks to non-privileged processes
Date: Wed, 6 May 2009 09:48:20 -0700 (PDT)	[thread overview]
Message-ID: <alpine.LFD.2.01.0905060942340.4983@localhost.localdomain> (raw)
In-Reply-To: <20090506162543.GT31071@waste.org>

On Wed, 6 May 2009, Matt Mackall wrote:

> On Wed, May 06, 2009 at 12:30:34PM +0200, Ingo Molnar wrote:
> > (Also, obviously "only" covering 95% of the Linux systems has its 
> > use as well. Most other architectures have their own cycle counters 
> > as well.)
> 
> X86 might be 95% of desktop. But it's a small fraction of Linux
> systems once you count cell phones, video players, TVs, cameras, GPS
> devices, cars, routers, etc. almost none of which are x86-based. In
> fact, just Linux cell phones (with about an 8% share of a 1.2billion
> devices per year market) dwarf Linux desktops (maybe 5% of a
> 200m/y market).

Matt, are you willing to ack my suggested patch which adds history to the 
mix? Did somebody test that? I have this memory of there being an 
"exploit" program to show the non-randomness of the values, but I can't 
recall details, and would really want to get a second opinion from 
somebody who cares about PRNG's.

			Linus