From: Stefan Hajnoczi <stefanha@gmail.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Max Moroz <mmoroz@google.com>, Dmitry Vyukov <dvyukov@google.com>,
Oliver Chang <ochang@google.com>,
Jonathan Metzman <metzman@google.com>,
Bandan Das <bsd@redhat.com>, qemu-devel <qemu-devel@nongnu.org>,
Andrey Konovalov <andreyknvl@google.com>,
Kostya Serebryany <kcc@google.com>
Subject: Re: [Qemu-devel] Internship idea: virtio-blk oss-fuzz support
Date: Mon, 14 Jan 2019 09:24:59 +0000 [thread overview]
Message-ID: <20190114092459.GA7038@stefanha-x1.localdomain> (raw)
In-Reply-To: <0387b8e9-2b4f-ce1a-05df-b508851b84f0@redhat.com>
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On Fri, Jan 11, 2019 at 05:16:40PM +0100, Paolo Bonzini wrote:
> On 11/01/19 16:41, Max Moroz wrote:
> > On Fri, Jan 11, 2019 at 7:34 AM Paolo Bonzini <pbonzini@redhat.com
> > <mailto:pbonzini@redhat.com>> wrote:
> >
> > On 11/01/19 16:04, Max Moroz wrote:
> > > We usually have a single fuzzing process, it starts with a fuzzing
> > > engine's main function and is calling LLVMFuzzerTestOneInput with
> > > various inputs and keep mutating them based on the coverage feedback.
> > > Running a second process which you don't care too much about might be
> > > fine, but the fuzzing process should be "replacing" or should I say
> > > "imitating" the process whose coverage you're interested in.
> >
> > What do you mean by replacing or imitating?
> >
> > To give you an example, when we fuzz ffmpeg, we do not run ffmpeg's main
> > function. We write LLVMFuzzerTestOneInput that would do the necessary
> > initialization, reset the state, etc, and then would pass (data, size)
> > provided by a fuzzing engine to the API(s) we're trying to fuzz. So, in
> > your case, there should not be a regular QEMU process, and instead the
> > fuzz target (i.e. LLVMFuzzerTestOneInput) should be doing certain
> > initialization (which is usually done by the QEMU process) and then call
> > the API you want to fuzz.
>
> The main issue is that we are not really testing an API and QEMU has a
> lot of global state.
With regards to the GSoC/Outreachy project, I think the mentors (me?)
need to figure this out beforehand by experimentation. The QEMU folks
don't know the details of oss-fuzz and vice versa. But with a weekend
or two's worth of playing around we could figure out a reasonable way of
integrating qtest/oss-fuzz.
Then the intern has a clear direction to follow this summer and won't be
demotivated by failed attempts at working with two codebases they are
unfamiliar with :).
Stefan
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next prev parent reply other threads:[~2019-01-14 9:25 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-09 17:34 [Qemu-devel] Internship idea: virtio-blk oss-fuzz support Stefan Hajnoczi
2019-01-10 10:46 ` Dmitry Vyukov
2019-01-10 13:40 ` Bandan Das
2019-01-10 14:01 ` Dmitry Vyukov
2019-01-10 16:07 ` Max Moroz
2019-01-10 23:25 ` Paolo Bonzini
2019-01-11 6:49 ` Stefan Hajnoczi
2019-01-11 15:04 ` Max Moroz
2019-01-11 15:33 ` Paolo Bonzini
2019-01-11 15:41 ` Max Moroz
2019-01-11 16:16 ` Paolo Bonzini
2019-01-11 19:09 ` Jonathan Metzman
2019-01-11 20:27 ` Paolo Bonzini
2019-01-11 22:56 ` Jonathan Metzman
2019-01-14 9:24 ` Stefan Hajnoczi [this message]
2019-01-18 7:51 ` Bandan Das
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