linux-kernel - Re: perf/tracepoint: another fuzzer generated lockup

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

Date:	Sat, 9 Nov 2013 17:08:31 +0100
From:	Frederic Weisbecker <fweisbec@...il.com>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	Vince Weaver <vincent.weaver@...ne.edu>,
	Steven Rostedt <rostedt@...dmis.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Ingo Molnar <mingo@...nel.org>, Dave Jones <davej@...hat.com>
Subject: Re: perf/tracepoint: another fuzzer generated lockup

On Sat, Nov 09, 2013 at 04:59:38PM +0100, Peter Zijlstra wrote:
> On Sat, Nov 09, 2013 at 04:27:01PM +0100, Frederic Weisbecker wrote:
> > In fact, raising an irq work from an irq work should simply be prohibited. That's not a sane
> > behaviour.
> 
> Well, it is because as you raised on IRC we could be holding locks and
> trying to avoid deadlocks. This is the very reason irq_work gets used in
> printk.
> 
> And its not a recursive run()->work()->queue() either, because as you said this
> tracepoint is in arch code _after_ work_run completes.

Yeah, indeed :(

> 
> All in all an exceedingly vexing issue.

Yep, the only sane way to solve this now is to check that signal pending, unfortunately
as you said it's not acquired that we can even just check this lockless...
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/