From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail143.messagelabs.com (mail143.messagelabs.com [216.82.254.35]) by kanga.kvack.org (Postfix) with ESMTP id 656898D0039 for ; Fri, 4 Mar 2011 17:10:41 -0500 (EST) Received: by yws5 with SMTP id 5so1195884yws.14 for ; Fri, 04 Mar 2011 14:10:39 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <1299275042.2071.1422.camel@dan> References: <1299174652.2071.12.camel@dan> <1299185882.3062.233.camel@calx> <1299186986.2071.90.camel@dan> <1299188667.3062.259.camel@calx> <1299191400.2071.203.camel@dan> <2DD7330B-2FED-4E58-A76D-93794A877A00@mit.edu> <1299260164.8493.4071.camel@nimitz> <1299262495.3062.298.camel@calx> <1299270709.3062.313.camel@calx> <1299271377.2071.1406.camel@dan> <1299272907.2071.1415.camel@dan> <1299275042.2071.1422.camel@dan> Date: Sat, 5 Mar 2011 00:10:39 +0200 Message-ID: Subject: Re: [PATCH] Make /proc/slabinfo 0400 From: Pekka Enberg Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Sender: owner-linux-mm@kvack.org List-ID: To: Dan Rosenberg Cc: Matt Mackall , Linus Torvalds , Dave Hansen , Theodore Tso , cl@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Ingo Molnar , Andrew Morton Hi Dan, On Fri, Mar 4, 2011 at 11:44 PM, Dan Rosenberg w= rote: > This is a good point, and one that I've come to accept as a result of > having this conversation. =A0Consider the patch dropped, unless there are > other reasons I've missed. =A0I still think it's worth brainstorming > techniques for hardening the kernel heap in ways that don't create > performance impact, but I admit that the presence or absence of this > debugging information isn't a crucial factor in successful exploitation. I can think of four things that will make things harder for the attacker (in the order of least theoretical performance impact): (1) disable slub merging (2) pin down random objects in the slab during setup (i.e. don't allow them to be allocated) (3) randomize the initial freelist (4) randomize padding between objects in a slab AFAICT, all of them will make brute force attacks using the kernel heap as an attack vector harder but won't prevent them. Pekka -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org