linux-kernel - Re: [PATCH 1/1] perf: Prevent race in PERF_SAMPLE

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Date:	Mon, 7 Jul 2014 13:43:46 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Jiri Olsa <jolsa@...hat.com>
Cc:	Jiri Olsa <jolsa@...nel.org>, linux-kernel@...r.kernel.org,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Corey Ashford <cjashfor@...ux.vnet.ibm.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Ingo Molnar <mingo@...nel.org>,
	Paul Mackerras <paulus@...ba.org>
Subject: Re: [PATCH 1/1] perf: Prevent race in PERF_SAMPLE_READ group format
 sample output

On Mon, Jul 07, 2014 at 12:20:20PM +0200, Jiri Olsa wrote:
> On Mon, Jul 07, 2014 at 11:04:28AM +0200, Peter Zijlstra wrote:
> > On Wed, Jun 25, 2014 at 08:44:35PM +0200, Jiri Olsa wrote:
> > > From: Jiri Olsa <jolsa@...hat.com>
> > > 
> > > While iterating siblings in perf_output_read_group we could
> > > race with addition and removal of sibling in perf_group_attach
> > > and perf_group_detach respective.
> > 
> > So why would anybody do this?
> 
> the test program from 0/1 email hangs up my server
> but no standard reason AFAICS
> 
> I've got soft lockup, sometimes ended up with unkillable perf process
> also few total server hangs

OK, so that's useful information to have in a Changelog ;-)

Not immediately obvious how that can happen though. I can see the output
getting scrambled.



Content of type "application/pgp-signature" skipped