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From:   Andrey Konovalov <andreyknvl@google.com>
Date:   Wed, 26 Aug 2020 14:30:34 +0200
Message-ID: <CAAeHK+yVShDPCxVKDsO_5SwoM2ZG7x7byUJ74PtB7ekY61L2YQ@mail.gmail.com>
Subject: Re: [PATCH v3 0/6] kasan: add workqueue and timer stack for generic KASAN
To:     Marco Elver <elver@google.com>
Cc:     Walter Wu <walter-zh.wu@mediatek.com>,
        Andrey Ryabinin <aryabinin@virtuozzo.com>,
        Alexander Potapenko <glider@google.com>,
        Dmitry Vyukov <dvyukov@google.com>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        John Stultz <john.stultz@linaro.org>,
        Stephen Boyd <sboyd@kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Tejun Heo <tj@kernel.org>,
        Lai Jiangshan <jiangshanlai@gmail.com>,
        kasan-dev <kasan-dev@googlegroups.com>,
        Linux Memory Management List <linux-mm@kvack.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Linux ARM <linux-arm-kernel@lists.infradead.org>,
        wsd_upstream <wsd_upstream@mediatek.com>,
        linux-mediatek@lists.infradead.org
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On Tue, Aug 25, 2020 at 10:26 AM 'Marco Elver' via kasan-dev
<kasan-dev@googlegroups.com> wrote:
>
> On Tue, 25 Aug 2020 at 03:57, Walter Wu <walter-zh.wu@mediatek.com> wrote:
> >
> > Syzbot reports many UAF issues for workqueue or timer, see [1] and [2].
> > In some of these access/allocation happened in process_one_work(),
> > we see the free stack is useless in KASAN report, it doesn't help
> > programmers to solve UAF on workqueue. The same may stand for times.
> >
> > This patchset improves KASAN reports by making them to have workqueue
> > queueing stack and timer stack information. It is useful for programmers
> > to solve use-after-free or double-free memory issue.
> >
> > Generic KASAN also records the last two workqueue and timer stacks and
> > prints them in KASAN report. It is only suitable for generic KASAN.
> >
> > [1]https://groups.google.com/g/syzkaller-bugs/search?q=%22use-after-free%22+process_one_work
> > [2]https://groups.google.com/g/syzkaller-bugs/search?q=%22use-after-free%22%20expire_timers
> > [3]https://bugzilla.kernel.org/show_bug.cgi?id=198437
> >
> > Walter Wu (6):
> > timer: kasan: record timer stack
> > workqueue: kasan: record workqueue stack
> > kasan: print timer and workqueue stack
> > lib/test_kasan.c: add timer test case
> > lib/test_kasan.c: add workqueue test case
> > kasan: update documentation for generic kasan
>
> Acked-by: Marco Elver <elver@google.com>

Reviewed-by: Andrey Konovalov <andreyknvl@google.com>

>
>
>
> > ---
> >
> > Changes since v2:
> > - modify kasan document to be more readable.
> >   Thanks for Marco suggestion.
> >
> > Changes since v1:
> > - Thanks for Marco and Thomas suggestion.
> > - Remove unnecessary code and fix commit log
> > - reuse kasan_record_aux_stack() and aux_stack
> >   to record timer and workqueue stack.
> > - change the aux stack title for common name.
> >
> > ---
> >
> > Documentation/dev-tools/kasan.rst |  4 ++--
> > kernel/time/timer.c               |  3 +++
> > kernel/workqueue.c                |  3 +++
> > lib/test_kasan.c                  | 54 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
> > mm/kasan/report.c                 |  4 ++--
> > 5 files changed, 64 insertions(+), 4 deletions(-)
> >
> > --
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