linux-kernel - Re: [RFC][PATCH 0/7] Sanitization of slabs based on grsecurity/PaX

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Date:	Thu, 21 Jan 2016 09:39:19 -0600 (CST)
From:	Christoph Lameter <cl@...ux.com>
To:	Laura Abbott <laura@...bott.name>
cc:	Kees Cook <keescook@...omium.org>,
	Pekka Enberg <penberg@...nel.org>,
	David Rientjes <rientjes@...gle.com>,
	Joonsoo Kim <iamjoonsoo.kim@....com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linux-MM <linux-mm@...ck.org>,
	LKML <linux-kernel@...r.kernel.org>,
	"kernel-hardening@...ts.openwall.com" 
	<kernel-hardening@...ts.openwall.com>
Subject: Re: [RFC][PATCH 0/7] Sanitization of slabs based on grsecurity/PaX

n Wed, 20 Jan 2016, Laura Abbott wrote:

> The SLAB_DEBUG flags force everything to skip the CPU caches which is
> causing the slow down. I experimented with allowing the debugging to
> happen with CPU caches but I'm not convinced it's possible to do the
> checking on the fast path in a consistent manner without adding
> locking. Is it worth refactoring the debugging to be able to be used
> on cpu caches or should I take the approach here of having the clear
> be separate from free_debug_processing?

At least posioning would benefit from such work. I think both
sanitization and posoning should be done by the same logic. Remove
poisoning if necessary.

Note though that this security stuff should not have a significant impact
on the general case.