Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752095Ab3HZTtp (ORCPT ); Mon, 26 Aug 2013 15:49:45 -0400 Received: from mx1.redhat.com ([209.132.183.28]:15635 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751745Ab3HZTto (ORCPT ); Mon, 26 Aug 2013 15:49:44 -0400 Date: Mon, 26 Aug 2013 15:49:24 -0400 From: Dave Jones To: David Ahern Cc: Steven Rostedt , paulmck@linux.vnet.ibm.com, Linux Kernel Subject: Re: suspicious RCU usage (perf) Message-ID: <20130826194923.GA1549@redhat.com> Mail-Followup-To: Dave Jones , David Ahern , Steven Rostedt , paulmck@linux.vnet.ibm.com, Linux Kernel References: <20130826145838.GA8377@redhat.com> <20130826162928.GQ3871@linux.vnet.ibm.com> <20130826133041.3d750b1b@gandalf.local.home> <20130826175012.GA25202@redhat.com> <20130826141814.54dcaa89@gandalf.local.home> <20130826182907.GB25202@redhat.com> <521BAFD3.2060404@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <521BAFD3.2060404@gmail.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1396 Lines: 37 On Mon, Aug 26, 2013 at 01:43:15PM -0600, David Ahern wrote: > On 8/26/13 12:29 PM, Dave Jones wrote: > > On Mon, Aug 26, 2013 at 02:18:14PM -0400, Steven Rostedt wrote: > > > On Mon, 26 Aug 2013 13:50:12 -0400 > > > Dave Jones wrote: > > > > > > > > This was triggered as a regular user fwiw. > > > > I had not been running perf, or any other tracing. It was just left > > > > fuzzing over the weekend with no interaction at all. > > > > > > So you are telling me that ftrace was enabled by a regular user? If so, > > > that's a huge issue. > > > > quite. > > > > > So my question to you. If you were not running perf or any other > > > tracing, and this is all just non-root user. How the hell did perf > > > function tracing get started on your box???? > > > > What mechanisms are available that would trigger it being enabled ? > > > > Is there some path through sys_perf_open_event that might be > > missing a capability check perhaps ? > > Do you have /sys/kernel/debug with access permissions? Ah, yeah, that'll be it. Good catch. Sorry for the false alarm Steve ;) Dave -- 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/