From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ig0-f174.google.com (mail-ig0-f174.google.com [209.85.213.174]) by kanga.kvack.org (Postfix) with ESMTP id 2FC536B0255 for ; Tue, 22 Dec 2015 11:25:03 -0500 (EST) Received: by mail-ig0-f174.google.com with SMTP id ph11so63668802igc.1 for ; Tue, 22 Dec 2015 08:25:03 -0800 (PST) Received: from resqmta-ch2-02v.sys.comcast.net (resqmta-ch2-02v.sys.comcast.net. [2001:558:fe21:29:69:252:207:34]) by mx.google.com with ESMTPS id i9si34618620igm.4.2015.12.22.08.25.02 for (version=TLS1_2 cipher=AES128-SHA bits=128/128); Tue, 22 Dec 2015 08:25:02 -0800 (PST) Date: Tue, 22 Dec 2015 10:25:00 -0600 (CST) From: Christoph Lameter Subject: Re: [kernel-hardening] [RFC][PATCH 6/7] mm: Add Kconfig option for slab sanitization In-Reply-To: <567964F3.2020402@intel.com> Message-ID: References: <1450755641-7856-1-git-send-email-laura@labbott.name> <1450755641-7856-7-git-send-email-laura@labbott.name> <567964F3.2020402@intel.com> Content-Type: text/plain; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: Dave Hansen Cc: kernel-hardening@lists.openwall.com, Pekka Enberg , David Rientjes , Joonsoo Kim , Andrew Morton , Laura Abbott , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Kees Cook On Tue, 22 Dec 2015, Dave Hansen wrote: > On 12/21/2015 07:40 PM, Laura Abbott wrote: > > + The tradeoff is performance impact. The noticible impact can vary > > + and you are advised to test this feature on your expected workload > > + before deploying it > > What if instead of writing SLAB_MEMORY_SANITIZE_VALUE, we wrote 0's? > That still destroys the information, but it has the positive effect of > allowing a kzalloc() call to avoid zeroing the slab object. It might > mitigate some of the performance impact. We already write zeros in many cases or the object is initialized in a different. No one really wants an uninitialized object. The problem may be that a freed object is having its old content until reused. Which is something that poisoning deals with. -- 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