Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756520Ab1EMGPb (ORCPT ); Fri, 13 May 2011 02:15:31 -0400 Received: from smtp.outflux.net ([198.145.64.163]:56911 "EHLO smtp.outflux.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751148Ab1EMGPa (ORCPT ); Fri, 13 May 2011 02:15:30 -0400 Date: Thu, 12 May 2011 23:12:52 -0700 From: Kees Cook To: Pekka Enberg Cc: David Miller , davej@redhat.com, eranian@google.com, acme@redhat.com, linux-kernel@vger.kernel.org, Linus Torvalds , Ingo Molnar Subject: Re: [BUG] perf: bogus correlation of kernel symbols Message-ID: <20110513061252.GV28888@outflux.net> References: <20110512.140630.1779004012724490077.davem@davemloft.net> <20110512183741.GA22269@redhat.com> <20110512.150132.1679483014638599288.davem@davemloft.net> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Organization: Canonical X-HELO: www.outflux.net Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1662 Lines: 43 Hi Pekka, On Thu, May 12, 2011 at 10:58:53PM +0300, Pekka Enberg wrote: > On Thu, May 12, 2011 at 10:01 PM, David Miller wrote: > > From: Dave Jones > > Date: Thu, 12 May 2011 14:37:41 -0400 > > > >> On Thu, May 12, 2011 at 02:06:30PM -0400, David Miller wrote: > >> ?> I hate this too, and I think it's absolutely rediculous. > >> ?> > >> ?> Also, like you, I lost an entire afternoon trying to figure out why > >> ?> this started happening. > >> ?> > >> ?> I wish we could revert this change. > >> > >> At least it can be permanently disabled.. > >> > >> echo kernel.kptr_restrict = 0 >> /etc/sysctl.conf > > > > Regardless, what to do about all of the "perf is broken" reports? > > Lets revert the commit 9f36e2c448007b54851e7e4fa48da97d1477a175 > ("printk: use %pK for /proc/kallsyms and /proc/modules"), please! I > too have been wondering what's going on with perf reporting insane > symbols and this should definitely not be enabled by default. No, reverting that is not the answer. If perf has a problem with the kptr_restrict feature, it should just disable it in /proc/sys when it runs and restore it when finished. Since our defaults should be secure for the average user (who does not use perf), it's fine the way it is. Anyone using perf can adjust this for their use-case (that is why there is a /proc/sys tunable). -Kees -- Kees Cook Ubuntu Security Team -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/