From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qt0-f198.google.com (mail-qt0-f198.google.com [209.85.216.198]) by kanga.kvack.org (Postfix) with ESMTP id C954F6B0292 for ; Thu, 29 Jun 2017 13:54:19 -0400 (EDT) Received: by mail-qt0-f198.google.com with SMTP id m54so43720888qtb.9 for ; Thu, 29 Jun 2017 10:54:19 -0700 (PDT) Received: from mx1.redhat.com (mx1.redhat.com. [209.132.183.28]) by mx.google.com with ESMTPS id k6si5321251qkc.164.2017.06.29.10.54.18 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 29 Jun 2017 10:54:19 -0700 (PDT) Message-ID: <1498758853.6130.2.camel@redhat.com> Subject: Re: [PATCH v2] mm: Add SLUB free list pointer obfuscation From: Rik van Riel Date: Thu, 29 Jun 2017 13:54:13 -0400 In-Reply-To: References: <20170623015010.GA137429@beast> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Kees Cook , Christoph Lameter Cc: Andrew Morton , Laura Abbott , Daniel Micay , Pekka Enberg , David Rientjes , Joonsoo Kim , "Paul E. McKenney" , Ingo Molnar , Josh Triplett , Andy Lutomirski , Nicolas Pitre , Tejun Heo , Daniel Mack , Sebastian Andrzej Siewior , Sergey Senozhatsky , Helge Deller , LKML , Linux-MM , "kernel-hardening@lists.openwall.com" On Thu, 2017-06-29 at 10:47 -0700, Kees Cook wrote: > On Thu, Jun 29, 2017 at 10:05 AM, Christoph Lameter > 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. I could certainly see it being useful for all kinds of portable and network-connected systems where security is simply much more important than performance. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org