From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751201AbdBWMuw (ORCPT ); Thu, 23 Feb 2017 07:50:52 -0500 Received: from mail.kernel.org ([198.145.29.136]:57550 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751049AbdBWMuu (ORCPT ); Thu, 23 Feb 2017 07:50:50 -0500 Date: Thu, 23 Feb 2017 09:50:08 -0300 From: Arnaldo Carvalho de Melo To: "Reshetova, Elena" Cc: "linux-kernel@vger.kernel.org" , "alsa-devel@alsa-project.org" , "peterz@infradead.org" , "gregkh@linuxfoundation.org" , "mingo@redhat.com" , "alexander.shishkin@linux.intel.com" , "jolsa@kernel.org" , "mark.rutland@arm.com" , "akpm@linux-foundation.org" , "matija.glavinic-pecotic.ext@nokia.com" Subject: Re: [PATCH 0/9] tools subsystem refcounter conversions Message-ID: <20170223125008.GB3595@kernel.org> References: <1487691303-31858-1-git-send-email-elena.reshetova@intel.com> <20170221153935.GE5052@kernel.org> <20170222232329.GN20447@kernel.org> <20170222232917.GO20447@kernel.org> <2236FBA76BA1254E88B949DDB74E612B41C4F449@IRSMSX102.ger.corp.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2236FBA76BA1254E88B949DDB74E612B41C4F449@IRSMSX102.ger.corp.intel.com> X-Url: http://acmel.wordpress.com User-Agent: Mutt/1.7.1 (2016-10-04) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Em Thu, Feb 23, 2017 at 11:39:10AM +0000, Reshetova, Elena escreveu: > > Em Wed, Feb 22, 2017 at 08:23:29PM -0300, Arnaldo Carvalho de Melo > > escreveu: > > > Em Tue, Feb 21, 2017 at 12:39:35PM -0300, Arnaldo Carvalho de Melo > > escreveu: > > > > Em Tue, Feb 21, 2017 at 05:34:54PM +0200, Elena Reshetova escreveu: > > > > > Now when new refcount_t type and API are finally merged > > > > > (see include/linux/refcount.h), the following > > > > > patches convert various refcounters in the tools susystem from atomic_t > > > > > to refcount_t. By doing this we prevent intentional or accidental > > > > > underflows or overflows that can led to use-after-free vulnerabilities. > > > > > > > > Thanks for working on this! I was almost going to jump on doing this > > > > myself! > > > > > > > > I'll try and get this merged ASAP. > > > > > > So, please take a look at my tmp.perf/refcount branch at: > > > > > > git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux.git > > I took a look on it and it looks good. Just one thing I want to double check with regards to this commit: > https://kernel.googlesource.com/pub/scm/linux/kernel/git/acme/linux/+/58d561002587bf2572f9e6f4d222659e4068fadf%5E%21/#F0 > > And more specifically to this chunk: > > @@ -937,7 +937,7 @@ > munmap(map->base, perf_mmap__mmap_len(map)); > map->base = NULL; > map->fd = -1; > - atomic_set(&map->refcnt, 0); > + refcount_set(&map->refcnt, 0); > } > auxtrace_mmap__munmap(&map->auxtrace_mmap); > } > So, when the refcount set to zero in this place, what exactly happens > to the perf_map object after? I just want to double check that we > don't have another hiding reusage case here when refcounter later on > is simply incremented vs. set to "2." So, this looks fishy and I don't recall why that was done that way, this conversion to refcnt_t and the debug associated with it provides a good opportunity for us to try to get that to a more familiar reference counting workflow, I'll take a look at it. - Arnaldo > > > There are multiple fixes in it to get it to build and test it, so far, > > > with: > > > > > > perf top -F 15000 -d 0 > > > > > > while doing kernel builds and tight usleep 1 loops to create lots of > > > short lived threads with its map_groups, maps, dsos, etc. > > > > > > Now running some build tests in some 36 containers with assorted distros > > > and cross compilers. > > > > Tomorrow I'll inject some refcount errors to test this all. > > > Thank you! > > Best Regards, > Elena. From mboxrd@z Thu Jan 1 00:00:00 1970 From: Arnaldo Carvalho de Melo Subject: Re: [PATCH 0/9] tools subsystem refcounter conversions Date: Thu, 23 Feb 2017 09:50:08 -0300 Message-ID: <20170223125008.GB3595@kernel.org> References: <1487691303-31858-1-git-send-email-elena.reshetova@intel.com> <20170221153935.GE5052@kernel.org> <20170222232329.GN20447@kernel.org> <20170222232917.GO20447@kernel.org> <2236FBA76BA1254E88B949DDB74E612B41C4F449@IRSMSX102.ger.corp.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <2236FBA76BA1254E88B949DDB74E612B41C4F449@IRSMSX102.ger.corp.intel.com> Sender: linux-kernel-owner@vger.kernel.org To: "Reshetova, Elena" Cc: "linux-kernel@vger.kernel.org" , "alsa-devel@alsa-project.org" , "peterz@infradead.org" , "gregkh@linuxfoundation.org" , "mingo@redhat.com" , "alexander.shishkin@linux.intel.com" , "jolsa@kernel.org" , "mark.rutland@arm.com" , "akpm@linux-foundation.org" , "matija.glavinic-pecotic.ext@nokia.com" List-Id: alsa-devel@alsa-project.org Em Thu, Feb 23, 2017 at 11:39:10AM +0000, Reshetova, Elena escreveu: > > Em Wed, Feb 22, 2017 at 08:23:29PM -0300, Arnaldo Carvalho de Melo > > escreveu: > > > Em Tue, Feb 21, 2017 at 12:39:35PM -0300, Arnaldo Carvalho de Melo > > escreveu: > > > > Em Tue, Feb 21, 2017 at 05:34:54PM +0200, Elena Reshetova escreveu: > > > > > Now when new refcount_t type and API are finally merged > > > > > (see include/linux/refcount.h), the following > > > > > patches convert various refcounters in the tools susystem from atomic_t > > > > > to refcount_t. By doing this we prevent intentional or accidental > > > > > underflows or overflows that can led to use-after-free vulnerabilities. > > > > > > > > Thanks for working on this! I was almost going to jump on doing this > > > > myself! > > > > > > > > I'll try and get this merged ASAP. > > > > > > So, please take a look at my tmp.perf/refcount branch at: > > > > > > git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux.git > > I took a look on it and it looks good. Just one thing I want to double check with regards to this commit: > https://kernel.googlesource.com/pub/scm/linux/kernel/git/acme/linux/+/58d561002587bf2572f9e6f4d222659e4068fadf%5E%21/#F0 > > And more specifically to this chunk: > > @@ -937,7 +937,7 @@ > munmap(map->base, perf_mmap__mmap_len(map)); > map->base = NULL; > map->fd = -1; > - atomic_set(&map->refcnt, 0); > + refcount_set(&map->refcnt, 0); > } > auxtrace_mmap__munmap(&map->auxtrace_mmap); > } > So, when the refcount set to zero in this place, what exactly happens > to the perf_map object after? I just want to double check that we > don't have another hiding reusage case here when refcounter later on > is simply incremented vs. set to "2." So, this looks fishy and I don't recall why that was done that way, this conversion to refcnt_t and the debug associated with it provides a good opportunity for us to try to get that to a more familiar reference counting workflow, I'll take a look at it. - Arnaldo > > > There are multiple fixes in it to get it to build and test it, so far, > > > with: > > > > > > perf top -F 15000 -d 0 > > > > > > while doing kernel builds and tight usleep 1 loops to create lots of > > > short lived threads with its map_groups, maps, dsos, etc. > > > > > > Now running some build tests in some 36 containers with assorted distros > > > and cross compilers. > > > > Tomorrow I'll inject some refcount errors to test this all. > > > Thank you! > > Best Regards, > Elena.