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Date: Thu, 14 Nov 2013 18:14:05 +0100
From: Peter Zijlstra <peterz@infradead.org>
To: Vince Weaver <vincent.weaver@maine.edu>
Cc: Frederic Weisbecker <fweisbec@gmail.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        LKML <linux-kernel@vger.kernel.org>, Ingo Molnar <mingo@kernel.org>,
        Dave Jones <davej@redhat.com>
Subject: Re: perf/tracepoint: another fuzzer generated lockup
Message-ID: <20131114171405.GA2965@twins.programming.kicks-ass.net>
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On Thu, Nov 14, 2013 at 12:20:35PM -0500, Vince Weaver wrote:
> 
> possibly not an issue with your patch, but found in nearby code:
> 
> in perf_trace_init:
> 
>         int event_id = p_event->attr.config;
> 
> 	...
> 
>                 if (tp_event->event.type == event_id &&
> 
> 
> note that "attr.config" is 64-bit but "event_id" is only 32-bit,
> so things like 0xffffffff00000018 will map to irq_work_exit.

I will have a look.

> I'm not sure if your PERM code properly handles this case, I don't have 
> time to work through the macro-magic in your patch.

Can't blame you; took me a fair chunk of the day to come up with this.
That trace event stuff is horrid.