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From:   Dmitry Vyukov <dvyukov@google.com>
Date:   Fri, 16 Apr 2021 09:21:12 +0200
Message-ID: <CACT4Y+aYfVxcXYOHwheW7Wp2oYcKm_zumeASo57Dy7deDfZJKA@mail.gmail.com>
Subject: Re: [syzbot] general protection fault in gadget_setup
To:     Alan Stern <stern@rowland.harvard.edu>
Cc:     syzbot <syzbot+eb4674092e6cc8d9e0bd@syzkaller.appspotmail.com>,
        Andrey Konovalov <andreyknvl@gmail.com>,
        Felipe Balbi <balbi@kernel.org>,
        Dan Carpenter <dan.carpenter@oracle.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        LKML <linux-kernel@vger.kernel.org>,
        USB list <linux-usb@vger.kernel.org>,
        syzkaller-bugs <syzkaller-bugs@googlegroups.com>,
        syzkaller <syzkaller@googlegroups.com>
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On Thu, Apr 15, 2021 at 10:59 PM Alan Stern <stern@rowland.harvard.edu> wrote:
>
> On Tue, Apr 13, 2021 at 07:11:11PM +0200, Dmitry Vyukov wrote:
> > On Tue, Apr 13, 2021 at 6:57 PM Alan Stern <stern@rowland.harvard.edu> wrote:
> > >
> > > On Tue, Apr 13, 2021 at 06:47:47PM +0200, Dmitry Vyukov wrote:
> > > > On Tue, Apr 13, 2021 at 6:13 PM Alan Stern <stern@rowland.harvard.edu> wrote:
> > > > > Hopefully this patch will make the race a lot more likely to occur.  Is
> > > > > there any way to tell syzkaller to test it, despite the fact that
> > > > > syzkaller doesn't think it has a reproducer for this issue?
> > > >
> > > > If there is no reproducer the only way syzbot can test it is if it's
> > > > in linux-next under CONFIG_DEBUG_AID_FOR_SYZBOT:
> > > > http://bit.do/syzbot#no-custom-patches
> > >
> > > There _is_ a theoretical reproducer: the test that provoked syzkaller's
> > > original bug report.  But syzkaller doesn't realize that it is (or may
> > > be) a reproducer.
> > >
> > > It ought to be possible to ask syzkaller to run a particular test that
> > > it has done before, with a patch applied -- and without having to add
> > > anything to linux-next.
> >
> > Yes, this is possible:
> > http://bit.do/syzbot#syzkaller-reproducers
>
> That's not really what I had in mind.  I don't want to spend the time
> and effort installing syskaller on my own system; I want to tell syzbot
> to run a particular syzkaller program (the one that originally led to
> this bug report) on a patched kernel.
>
> The syzbot instructions say that it can test bugs with reproducers.  The
> problem here is that there doesn't seem to be any way to tell it to use
> a particular syzkaller program as a reproducer.

Hi Alan,

This makes sense and I've found an existing feature request:
https://github.com/google/syzkaller/issues/1611
I've added a reference to this thread there.