Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
MIME-Version: 1.0
References: <20200825015654.27781-1-walter-zh.wu@mediatek.com>
 <CANpmjNOvj+=v7VDVDXpsUNZ9o0+KoJVJs0MjLhwr0XpYcYQZ5g@mail.gmail.com> <CAAeHK+yVShDPCxVKDsO_5SwoM2ZG7x7byUJ74PtB7ekY61L2YQ@mail.gmail.com>
In-Reply-To: <CAAeHK+yVShDPCxVKDsO_5SwoM2ZG7x7byUJ74PtB7ekY61L2YQ@mail.gmail.com>
From:   Dmitry Vyukov <dvyukov@google.com>
Date:   Sun, 13 Sep 2020 12:17:33 +0200
Message-ID: <CACT4Y+b1OimWNQCx-rGvSgC1RheLAv9mv2xzRnwkn98AsdTgXA@mail.gmail.com>
Subject: Re: [PATCH v3 0/6] kasan: add workqueue and timer stack for generic KASAN
To:     Andrey Konovalov <andreyknvl@google.com>
Cc:     Marco Elver <elver@google.com>,
        Walter Wu <walter-zh.wu@mediatek.com>,
        Andrey Ryabinin <aryabinin@virtuozzo.com>,
        Alexander Potapenko <glider@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
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Wed, Aug 26, 2020 at 2:30 PM 'Andrey Konovalov' via kasan-dev
<kasan-dev@googlegroups.com> wrote:
>
> 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> wro=
te:
> > >
> > > 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 programm=
ers
> > > to solve use-after-free or double-free memory issue.
> > >
> > > Generic KASAN also records the last two workqueue and timer stacks an=
d
> > > prints them in KASAN report. It is only suitable for generic KASAN.
> > >
> > > [1]https://groups.google.com/g/syzkaller-bugs/search?q=3D%22use-after=
-free%22+process_one_work
> > > [2]https://groups.google.com/g/syzkaller-bugs/search?q=3D%22use-after=
-free%22%20expire_timers
> > > [3]https://bugzilla.kernel.org/show_bug.cgi?id=3D198437
> > >
> > > 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>

Reviewed-by: Dmitry Vyukov <dvyukov@google.com>

Thanks! The UAF reports with RCU stacks that I see now are just =F0=9F=94=
=A5=F0=9F=94=A5=F0=9F=94=A5

> > > ---
> > >
> > > 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(-)
> > >
> > > --
> > > You received this message because you are subscribed to the Google Gr=
oups "kasan-dev" group.
> > > To unsubscribe from this group and stop receiving emails from it, sen=
d an email to kasan-dev+unsubscribe@googlegroups.com.
> > > To view this discussion on the web visit https://groups.google.com/d/=
msgid/kasan-dev/20200825015654.27781-1-walter-zh.wu%40mediatek.com.
> >
> > --
> > You received this message because you are subscribed to the Google Grou=
ps "kasan-dev" group.
> > To unsubscribe from this group and stop receiving emails from it, send =
an email to kasan-dev+unsubscribe@googlegroups.com.
> > To view this discussion on the web visit https://groups.google.com/d/ms=
gid/kasan-dev/CANpmjNOvj%2B%3Dv7VDVDXpsUNZ9o0%2BKoJVJs0MjLhwr0XpYcYQZ5g%40m=
ail.gmail.com.
>
> --
> You received this message because you are subscribed to the Google Groups=
 "kasan-dev" group.
> To unsubscribe from this group and stop receiving emails from it, send an=
 email to kasan-dev+unsubscribe@googlegroups.com.
> To view this discussion on the web visit https://groups.google.com/d/msgi=
d/kasan-dev/CAAeHK%2ByVShDPCxVKDsO_5SwoM2ZG7x7byUJ74PtB7ekY61L2YQ%40mail.gm=
ail.com.