linux-kernel - Re: OOPS in perf_mmap

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Message-ID: <alpine.DEB.2.10.1305281418120.19080@vincent-weaver-1.um.maine.edu>
Date:	Tue, 28 May 2013 14:22:11 -0400 (EDT)
From:	Vince Weaver <vincent.weaver@...ne.edu>
To:	Peter Zijlstra <peterz@...radead.org>
cc:	Al Viro <viro@...iv.linux.org.uk>, linux-kernel@...r.kernel.org,
	Paul Mackerras <paulus@...ba.org>,
	Ingo Molnar <mingo@...hat.com>,
	Arnaldo Carvalho de Melo <acme@...stprotocols.net>,
	trinity@...r.kernel.org
Subject: Re: OOPS in perf_mmap_close()

On Tue, 28 May 2013, Vince Weaver wrote:

> It looks like this is already in tip, but I can confirm that this 
> patch seems to fix things on my machine and holds up against longer 
> fuzzing runs.

OK, I take it back.  Even with the new patch applied, my fuzzer can still 
make the kernel leak user->locked_vm

I assume that the locked_vm value should go back to 0 once a process that 
has a bunch of mmap'd perf_events opened exits?

I admit this is sort of an obscure corner case, but it does mean that a 
user can leak user->locked_vm to the point that "perf record" no longer 
works.

Vince
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