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Subject: Re: [PATCH v2] task_work: kasan: record task_work_add() call stack
To:     Walter Wu <walter-zh.wu@mediatek.com>,
        Andrey Ryabinin <ryabinin.a.a@gmail.com>,
        Alexander Potapenko <glider@google.com>,
        Dmitry Vyukov <dvyukov@google.com>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        Andrey Konovalov <andreyknvl@google.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Oleg Nesterov <oleg@redhat.com>
Cc:     kasan-dev@googlegroups.com, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        wsd_upstream <wsd_upstream@mediatek.com>,
        linux-mediatek@lists.infradead.org
References: <20210316024410.19967-1-walter-zh.wu@mediatek.com>
From:   Jens Axboe <axboe@kernel.dk>
Message-ID: <7d5b6e38-2e11-06f7-0a6b-356bdda0cd5b@kernel.dk>
Date:   Tue, 16 Mar 2021 08:33:20 -0600
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On 3/15/21 8:44 PM, Walter Wu wrote:
> Why record task_work_add() call stack?
> Syzbot reports many use-after-free issues for task_work, see [1].
> After see the free stack and the current auxiliary stack, we think
> they are useless, we don't know where register the work, this work
> may be the free call stack, so that we miss the root cause and
> don't solve the use-after-free.
> 
> Add task_work_add() call stack into KASAN auxiliary stack in
> order to improve KASAN report. It is useful for programmers
> to solve use-after-free issues.

I think this is a very useful addition, especially as task_work
proliferates.

Reviewed-by: Jens Axboe <axboe@kernel.dk>

-- 
Jens Axboe