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From:   Dmitry Vyukov <dvyukov@google.com>
Date:   Thu, 3 Dec 2020 08:01:35 +0100
Message-ID: <CACT4Y+aQ19fUhDZMeLQeVzdECQhje6CpnH4SVmMQtS_cTPq0zg@mail.gmail.com>
Subject: Re: [PATCH v5 0/4] kasan: add workqueue stack for generic KASAN
To:     Walter Wu <walter-zh.wu@mediatek.com>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        Tejun Heo <tj@kernel.org>,
        Lai Jiangshan <jiangshanlai@gmail.com>,
        Marco Elver <elver@google.com>,
        Andrey Ryabinin <aryabinin@virtuozzo.com>,
        Alexander Potapenko <glider@google.com>,
        Andrey Konovalov <andreyknvl@google.com>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        kasan-dev <kasan-dev@googlegroups.com>,
        Linux-MM <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 Thu, Dec 3, 2020 at 3:21 AM Walter Wu <walter-zh.wu@mediatek.com> wrote:
>
> Syzbot reports many UAF issues for workqueue, see [1].
> 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 for workqueue issue.
>
> This patchset improves KASAN reports by making them to have workqueue
> queueing stack. It is useful for programmers to solve use-after-free
> or double-free memory issue.
>
> Generic KASAN also records the last two workqueue 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://bugzilla.kernel.org/show_bug.cgi?id=198437
>
> Walter Wu (4):
> workqueue: kasan: record workqueue stack
> kasan: print workqueue stack
> lib/test_kasan.c: add workqueue test case
> kasan: update documentation for generic kasan
>
> ---
> Changes since v4:
> - Not found timer use case, so that remove timer patch
> - remove a mention of call_rcu() from the kasan_record_aux_stack()
>   Thanks for Dmitry and Alexander suggestion.
>
> Changes since v3:
> - testcases have merge conflict, so that need to
>   be rebased onto the KASAN-KUNIT.
>
> Changes since v2:
> - modify kasan document to be 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 |  5 +++--
> kernel/workqueue.c                |  3 +++
> lib/test_kasan_module.c           | 29 +++++++++++++++++++++++++++++
> mm/kasan/generic.c                |  4 +---
> mm/kasan/report.c                 |  4 ++--
> 5 files changed, 38 insertions(+), 7 deletions(-)


Hi Walter,

Thanks for the update.
The series still looks good to me. I see patches already have my
Reviewed-by, so I will not resend them.