linux-kernel - Re: perf/ftrace: fuzzer triggers another warning with PERF_EVENT_IOC_SET

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Date:	Thu, 18 Jun 2015 17:18:47 -0400 (EDT)
From:	Vince Weaver <vincent.weaver@...ne.edu>
To:	Steven Rostedt <rostedt@...dmis.org>
cc:	Vince Weaver <vincent.weaver@...ne.edu>,
	linux-kernel@...r.kernel.org,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Ingo Molnar <mingo@...hat.com>,
	Arnaldo Carvalho de Melo <acme@...nel.org>
Subject: Re: perf/ftrace: fuzzer triggers another warning with
 PERF_EVENT_IOC_SET_FILTER

On Thu, 18 Jun 2015, Steven Rostedt wrote:

> On Wed, 17 Jun 2015 19:32:26 -0400 (EDT)
> Vince Weaver <vincent.weaver@...ne.edu> wrote:
> 
> > 
> > The fuzzer triggered another warning in the PERF_EVENT_IOC_SET_FILTER 
> > code.  This is with the previous filter patch applied.
> > 
> > >From what I can tell the filter was:
> > nfs4:nfs4_fsinfo 
> > (((fhandle~601)&&valid&809)&&common_type>=860) 
> 
> Hmm, I can't trigger this with the filter file, can you?
> 
>  echo '(((fhandle~601)&&valid&809)&&common_type>=860)' > \
>   /sys/kernel/debug/tracing/events/nfs4/nfs4_fsinfo/filter
> 
> I'll write a user app to use the perf syscall and see if that is
> different, but in the mean time, can you try the above.

I can't seem to replicate this with perf or echo.

Unfortunately I made many changes to the fuzzer since hitting the bug so 
it's a bit hard to replicate with the fuzzer.  I'll keep fuzzing and see 
if I can hit it again.

As an aside, I can't find any documentation of how the "~" glob operator 
works in ftrace filters.  Can you give a quick example of a valid filter 
that uses it?

Thanks,

Vince
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