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From:   Andrey Konovalov <andreyknvl@google.com>
Date:   Mon, 25 May 2020 19:36:27 +0200
Message-ID: <CAAeHK+y9qz5P-WCWEGwUx__XVzPXTddcOXsFDnFvh_1-k4Opxw@mail.gmail.com>
Subject: Re: [PATCH v6 0/4] kasan: memorize and print call_rcu stack
To:     Walter Wu <walter-zh.wu@mediatek.com>
Cc:     Andrey Ryabinin <aryabinin@virtuozzo.com>,
        Alexander Potapenko <glider@google.com>,
        Dmitry Vyukov <dvyukov@google.com>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        "Paul E . McKenney" <paulmck@kernel.org>,
        Josh Triplett <josh@joshtriplett.org>,
        Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
        Lai Jiangshan <jiangshanlai@gmail.com>,
        Joel Fernandes <joel@joelfernandes.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        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 Fri, May 22, 2020 at 3:58 AM Walter Wu <walter-zh.wu@mediatek.com> wrote:
>
> This patchset improves KASAN reports by making them to have
> call_rcu() call stack information. It is useful for programmers
> to solve use-after-free or double-free memory issue.
>
> The KASAN report was as follows(cleaned up slightly):
>
> BUG: KASAN: use-after-free in kasan_rcu_reclaim+0x58/0x60
>
> Freed by task 0:
>  kasan_save_stack+0x24/0x50
>  kasan_set_track+0x24/0x38
>  kasan_set_free_info+0x18/0x20
>  __kasan_slab_free+0x10c/0x170
>  kasan_slab_free+0x10/0x18
>  kfree+0x98/0x270
>  kasan_rcu_reclaim+0x1c/0x60
>
> Last call_rcu():
>  kasan_save_stack+0x24/0x50
>  kasan_record_aux_stack+0xbc/0xd0
>  call_rcu+0x8c/0x580
>  kasan_rcu_uaf+0xf4/0xf8
>
> Generic KASAN will record the last two call_rcu() call stacks and
> print up to 2 call_rcu() call stacks in KASAN report. it is only
> suitable for generic KASAN.
>
> This feature considers the size of struct kasan_alloc_meta and
> kasan_free_meta, we try to optimize the structure layout and size
> , let it get better memory consumption.
>
> [1]https://bugzilla.kernel.org/show_bug.cgi?id=198437
> [2]https://groups.google.com/forum/#!searchin/kasan-dev/better$20stack$20traces$20for$20rcu%7Csort:date/kasan-dev/KQsjT_88hDE/7rNUZprRBgAJ

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

for the series.

Thanks!

>
> Changes since v2:
> - remove new config option, default enable it in generic KASAN
> - test this feature in SLAB/SLUB, it is pass.
> - modify macro to be more clearly
> - modify documentation
>
> Changes since v3:
> - change recording from first/last to the last two call stacks
> - move free track into kasan free meta
> - init slab_free_meta on object slot creation
> - modify documentation
>
> Changes since v4:
> - change variable name to be more clearly
> - remove the redundant condition
> - remove init free meta-data and increasing object condition
>
> Changes since v5:
> - add a macro KASAN_KMALLOC_FREETRACK in order to check whether
>   print free stack
> - change printing message
> - remove descriptions in Kocong.kasan
>
> Changes since v6:
> - reuse print_stack() in print_track()
>
> Walter Wu (4):
> rcu/kasan: record and print call_rcu() call stack
> kasan: record and print the free track
> kasan: add tests for call_rcu stack recording
> kasan: update documentation for generic kasan
>
> Documentation/dev-tools/kasan.rst |  3 +++
> include/linux/kasan.h             |  2 ++
> kernel/rcu/tree.c                 |  2 ++
> lib/test_kasan.c                  | 30 ++++++++++++++++++++++++++++++
> mm/kasan/common.c                 | 26 ++++----------------------
> mm/kasan/generic.c                | 43 +++++++++++++++++++++++++++++++++++++++++++
> mm/kasan/generic_report.c         |  1 +
> mm/kasan/kasan.h                  | 23 +++++++++++++++++++++--
> mm/kasan/quarantine.c             |  1 +
> mm/kasan/report.c                 | 54 +++++++++++++++++++++++++++---------------------------
> mm/kasan/tags.c                   | 37 +++++++++++++++++++++++++++++++++++++
> 11 files changed, 171 insertions(+), 51 deletions(-)
>
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