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From:   Dmitry Vyukov <dvyukov@google.com>
Date:   Tue, 1 Dec 2020 15:51:14 +0100
Message-ID: <CACT4Y+bWm_bPdbes60u=3d_u34yxBBC7rGQz1yAt1FQXXqP4-A@mail.gmail.com>
Subject: Re: [PATCH v4 0/6] kasan: add workqueue and timer stack for generic KASAN
To:     Thomas Gleixner <tglx@linutronix.de>
Cc:     Walter Wu <walter-zh.wu@mediatek.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        John Stultz <john.stultz@linaro.org>,
        Stephen Boyd <sboyd@kernel.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 Tue, Dec 1, 2020 at 3:13 PM Thomas Gleixner <tglx@linutronix.de> 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.
> >
> > Walter, did you mail v5?
> > Checking statuses of KASAN issues and this seems to be not in linux-next.
> >
> >> > [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
> >>
> >> How are these links useful for people who do not have a gurgle account?
> >
> > This is a public mailing list archive, so effectively the same way as
> > lore links ;)
>
> Just that it asked me to log in last time. That's why I wrote the
> above. Today it does not, odd.

Some random permissions settings changes were observed before, so I
can believe that.