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From: Kees Cook <keescook@chromium.org>
To: Christoph Lameter <cl@linux.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Laura Abbott <labbott@redhat.com>,
	Daniel Micay <danielmicay@gmail.com>,
	Pekka Enberg <penberg@kernel.org>,
	David Rientjes <rientjes@google.com>,
	Joonsoo Kim <iamjoonsoo.kim@lge.com>,
	"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
	Ingo Molnar <mingo@kernel.org>,
	Josh Triplett <josh@joshtriplett.org>,
	Andy Lutomirski <luto@kernel.org>,
	Nicolas Pitre <nicolas.pitre@linaro.org>,
	Tejun Heo <tj@kernel.org>, Daniel Mack <daniel@zonque.org>,
	Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
	Helge Deller <deller@gmx.de>, Rik van Riel <riel@redhat.com>,
	LKML <linux-kernel@vger.kernel.org>,
	Linux-MM <linux-mm@kvack.org>,
	"kernel-hardening@lists.openwall.com" 
	<kernel-hardening@lists.openwall.com>
Subject: Re: [PATCH v2] mm: Add SLUB free list pointer obfuscation
Date: Thu, 29 Jun 2017 10:47:27 -0700	[thread overview]
Message-ID: <CAGXu5jLLFKnboaLJKGcGT-Ra80ZzAf3jZ=zex6vd8uDQamBJxg@mail.gmail.com> (raw)
In-Reply-To: <alpine.DEB.2.20.1706291204460.17478@east.gentwo.org>

On Thu, Jun 29, 2017 at 10:05 AM, Christoph Lameter <cl@linux.com> wrote:
> On Sun, 25 Jun 2017, Kees Cook wrote:
>
>> The difference gets lost in the noise, but if the above is sensible,
>> it's 0.07% slower. ;)
>
> Hmmm... These differences add up. Also in a repetative benchmark like that
> you do not see the impact that the additional cacheline use in the cpu
> cache has on larger workloads. Those may be pushed over the edge of l1 or
> l2 capacity at some point which then causes drastic regressions.

Even if that is true, it may be worth it to some people to have the
protection. Given that is significantly hampers a large class of heap
overflow attacks[1], I think it's an important change to have. I'm not
suggesting this be on by default, it's cleanly behind
CONFIG-controlled macros, and is very limited in scope. If you can Ack
it we can let system builders decide if they want to risk a possible
performance hit. I'm pretty sure most distros would like to have this
protection.

Thanks for looking it over!

-Kees

[1] http://resources.infosecinstitute.com/exploiting-linux-kernel-heap-corruptions-slub-allocator/

-- 
Kees Cook
Pixel Security

  reply	other threads:[~2017-06-29 17:47 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-06-23  1:50 [PATCH v2] mm: Add SLUB free list pointer obfuscation Kees Cook
2017-06-25 19:56 ` Kees Cook
2017-06-29 17:05   ` Christoph Lameter
2017-06-29 17:47     ` Kees Cook [this message]
2017-06-29 17:54       ` Rik van Riel
2017-06-29 17:56         ` [kernel-hardening] " Tycho Andersen
2017-07-05 23:30           ` Kees Cook
2017-07-05 23:39 ` Andrew Morton
2017-07-05 23:56   ` Kees Cook

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