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References: <20220905122754.32590-1-alexander.sverdlin@nokia.com>
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From:   Linus Walleij <linus.walleij@linaro.org>
Date:   Mon, 5 Sep 2022 15:38:25 +0200
Message-ID: <CACRpkdbdKAWfvpG2n-eJPagV3Sx1faaxC9cEFs3PTyDaxETwyQ@mail.gmail.com>
Subject: Re: [PATCH v2] ARM: kasan: Only map modules if CONFIG_KASAN_VMALLOC=n
To:     Alexander A Sverdlin <alexander.sverdlin@nokia.com>
Cc:     kasan-dev@googlegroups.com,
        Lecopzer Chen <lecopzer.chen@mediatek.com>,
        Andrey Ryabinin <ryabinin.a.a@gmail.com>,
        Alexander Potapenko <glider@google.com>,
        Andrey Konovalov <andreyknvl@gmail.com>,
        Dmitry Vyukov <dvyukov@google.com>,
        Vincenzo Frascino <vincenzo.frascino@arm.com>,
        Russell King <linux@armlinux.org.uk>,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org
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On Mon, Sep 5, 2022 at 2:28 PM Alexander A Sverdlin
<alexander.sverdlin@nokia.com> wrote:

> From: Alexander Sverdlin <alexander.sverdlin@nokia.com>
>
> In case CONFIG_KASAN_VMALLOC=y kasan_populate_vmalloc() allocates the
> shadow pages dynamically. But even worse is that kasan_release_vmalloc()
> releases them, which is not compatible with create_mapping() of
> MODULES_VADDR..MODULES_END range:
>
> BUG: Bad page state in process kworker/9:1  pfn:2068b
> page:e5e06160 refcount:0 mapcount:0 mapping:00000000 index:0x0
> flags: 0x1000(reserved)
> raw: 00001000 e5e06164 e5e06164 00000000 00000000 00000000 ffffffff 00000000
> page dumped because: PAGE_FLAGS_CHECK_AT_FREE flag(s) set
> bad because of flags: 0x1000(reserved)
> Modules linked in: ip_tables
> CPU: 9 PID: 154 Comm: kworker/9:1 Not tainted 5.4.188-... #1
> Hardware name: LSI Axxia AXM55XX
> Workqueue: events do_free_init
> unwind_backtrace
> show_stack
> dump_stack
> bad_page
> free_pcp_prepare
> free_unref_page
> kasan_depopulate_vmalloc_pte
> __apply_to_page_range
> apply_to_existing_page_range
> kasan_release_vmalloc
> __purge_vmap_area_lazy
> _vm_unmap_aliases.part.0
> __vunmap
> do_free_init
> process_one_work
> worker_thread
> kthread
>
> Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
> Signed-off-by: Alexander Sverdlin <alexander.sverdlin@nokia.com>

Thanks Alexander, will you submit this to Russell's patch tracker please?

Yours,
Linus Walleij