netdev - Re: [Security] [SECURITY] Fix leaking of kernel heap addresses via /proc

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Message-ID: <20101106234840.GD2935@thunk.org>
Date:	Sat, 6 Nov 2010 19:48:40 -0400
From:	Ted Ts'o <tytso@....edu>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	Dan Rosenberg <drosenberg@...curity.com>,
	"chas@....nrl.navy.mil" <chas@....nrl.navy.mil>,
	"davem@...emloft.net" <davem@...emloft.net>,
	"kuznet@....inr.ac.ru" <kuznet@....inr.ac.ru>,
	"pekkas@...core.fi" <pekkas@...core.fi>,
	"jmorris@...ei.org" <jmorris@...ei.org>,
	"yoshfuji@...ux-ipv6.org" <yoshfuji@...ux-ipv6.org>,
	"kaber@...sh.net" <kaber@...sh.net>,
	"remi.denis-courmont@...ia.com" <remi.denis-courmont@...ia.com>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"security@...nel.org" <security@...nel.org>
Subject: Re: [Security] [SECURITY] Fix leaking of kernel heap addresses via
 /proc

On Sat, Nov 06, 2010 at 01:50:32PM -0700, Linus Torvalds wrote:
> On Saturday, November 6, 2010, Dan Rosenberg <drosenberg@...curity.com> wrote:
> > Clearly, in most cases we cannot just remove the field from the /proc
> > output, as this would break a number of userspace programs that rely on
> > consistency.  However, I propose that we replace the address with a "0"
> > rather than leaking this information.
> 
> I really think it would be much better to use the unidentified number
> or similar.
> 
> Just replacing with zeroes is annoying, and has the potential of
> losing actual information.

Are there any userspace programs that might be reasonably expected to
_use_ this information?  If there is, we could just pick a random
number at boot time, and then XOR the heap adddress with that random
number.

						- Ted
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