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Message-ID: <2236FBA76BA1254E88B949DDB74E612B41BDAB84@IRSMSX102.ger.corp.intel.com>
Date: Tue, 4 Oct 2016 06:24:29 +0000
From: "Reshetova, Elena" <elena.reshetova@...el.com>
To: Kees Cook <keescook@...omium.org>
CC: "kernel-hardening@...ts.openwall.com"
	<kernel-hardening@...ts.openwall.com>, Hans Liljestrand
	<ishkamiel@...il.com>, David Windsor <dwindsor@...il.com>
Subject: RE: [RFC PATCH 02/13] percpu-refcount: leave atomic counter
 unprotected

On Sun, Oct 2, 2016 at 11:41 PM, Elena Reshetova <elena.reshetova@...el.com> wrote:
> From: Hans Liljestrand <ishkamiel@...il.com>
>
> This is a temporary solution, and a deviation from the PaX/Grsecurity 
> implementation where the counter in question is protected against 
> overflows. That however necessitates decreasing the PERCPU_COUNT_BIAS 
> which is used in lib/percpu-refcount.c. Such a change effectively cuts 
> the safe counter range down by half, and still allows the counter to, 
> without warning, prematurely reach zero (which is what the bias aims 
> to prevent).

>It might be useful to include a link to the earlier discussions that led to this solution.

Big part of it was in private emails, not sure how to reference that. Maybe we can just add more explanation here?

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