linux-kernel - Re: [for-next][PATCH 14/14] tracing: Get trace_array ref counts when accessing trace files

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Message-ID: <20140410093324.2b91f0e0@gandalf.local.home>
Date:	Thu, 10 Apr 2014 09:33:24 -0400
From:	Steven Rostedt <rostedt@...dmis.org>
To:	Steven Rostedt <rostedt@...dmis.org>
Cc:	Sasha Levin <sasha.levin@...cle.com>, linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	"H. Peter Anvin" <hpa@...or.com>, Al Viro <viro@...IV.linux.org.uk>
Subject: Re: [for-next][PATCH 14/14] tracing: Get trace_array ref counts
 when accessing trace files

On Tue, 8 Apr 2014 13:32:31 -0400
Steven Rostedt <rostedt@...dmis.org> wrote:

> On Tue, 08 Apr 2014 13:11:32 -0400
> Sasha Levin <sasha.levin@...cle.com> wrote:
> 
> > >>
> > >> Although when I mount everything for the fuzzer I do it with '-onoexec,nosuid'
> > >> and the fuzzer is banned from testing mount(), so I'm not sure how it would
> > >> do that thing on it's own.
> > > 
> > > What does the -onoexec do? Not change the exec flag of files?
> > 
> > It lets you set it as executable, but it won't let you actually exec it.
> > 
> > > Also, I wonder if this has something to do with the syscall being a
> > > compat sys_exec and not a native one. Is userspace on your vm 32bit? Or
> > > does the fuzzer just try the different compat calls?
> > 
> > Right, everything is 64bit but the fuzzer tries 32bit calls as well.
> 
> When this bug is triggered, is there a way to let the fuzzer tell us
> what exactly the last syscall it sent was? That is, the syscall number
> plus all its arguments?

Just letting you know. I'm holding off looking too deep into this as it
seems to require very strange behavior to trigger (like perhaps execing
a tracing file). This only happens when running as root, right? If not,
then there's a bigger bug involved.

If you can get me more information on this bug, like what I suggested
above, then I'll take another look.

Thanks,

-- Steve
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