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Date:   Thu, 9 Apr 2020 22:45:59 +0200 (CEST)
From:   Julia Lawall <julia.lawall@inria.fr>
To:     Alexander Popov <alex.popov@linux.com>
cc:     Gilles Muller <Gilles.Muller@lip6.fr>,
        Nicolas Palix <nicolas.palix@imag.fr>,
        Michal Marek <michal.lkml@markovi.net>, cocci@systeme.lip6.fr,
        "kernel-hardening@lists.openwall.com" 
        <kernel-hardening@lists.openwall.com>,
        Jann Horn <jannh@google.com>,
        Kees Cook <keescook@chromium.org>,
        Hans Verkuil <hverkuil@xs4all.nl>,
        Mauro Carvalho Chehab <mchehab@kernel.org>,
        Linux Media Mailing List <linux-media@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Markus Elfring <Markus.Elfring@web.de>
Subject: Re: [Cocci] Coccinelle rule for CVE-2019-18683
In-Reply-To: <3c92523d-4b3f-e805-84e6-6abd1eedd683@linux.com>
Message-ID: <alpine.DEB.2.21.2004092242450.2403@hadrien>
References: <fff664e9-06c9-d2fb-738f-e8e591e09569@linux.com> <alpine.DEB.2.21.2004091248190.2403@hadrien> <3c92523d-4b3f-e805-84e6-6abd1eedd683@linux.com>
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> >> kthread_stop@stop_p(...)
> >> ...
> >> mutex_lock@lock_p(E)
> >>
> >> @script:python@
> >> stop_p << race.stop_p;
> >> unlock_p << race.unlock_p;
> >> lock_p << race.lock_p;
> >> E << race.E;
> >> @@
> >>
> >> coccilib.report.print_report(unlock_p[0], 'mutex_unlock(' + E + ') here')
> >> coccilib.report.print_report(stop_p[0], 'kthread_stop here')
> >> coccilib.report.print_report(lock_p[0], 'mutex_lock(' + E + ') here\n')
>
> ...
>
> > Based on Jann's suggestion, it seem like it could be interesting to find
> > these locking pauses, and then collect functions that are used in locks
> > and in lock pauses.  If a function is mostly used with locks held, then
> > using it in a lock pause could be a sign of a bug.  I will see if it turns
> > up anything interesting.
>
> Do you mean collecting the behaviour that happens between unlocking and locking
> and then analysing it somehow?

Yes.  I have tried doing what I described, but I'm not sure that the
results are very reliable at the moment.

julia