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From:   Marco Elver <elver@google.com>
Date:   Thu, 12 Aug 2021 10:56:43 +0200
Message-ID: <CANpmjNMNMoPc8S_xTG3ANBZkVsanq=vnsAPkL=pe+cOXbTySzw@mail.gmail.com>
Subject: Re: [PATCH 5/8] kasan: test: only do kmalloc_uaf_memset for generic mode
To:     andrey.konovalov@linux.dev
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        Andrey Konovalov <andreyknvl@gmail.com>,
        Andrey Ryabinin <aryabinin@virtuozzo.com>,
        Dmitry Vyukov <dvyukov@google.com>,
        Alexander Potapenko <glider@google.com>,
        kasan-dev@googlegroups.com, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org
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On Wed, 11 Aug 2021 at 21:21, <andrey.konovalov@linux.dev> wrote:
> From: Andrey Konovalov <andreyknvl@gmail.com>
>
> kmalloc_uaf_memset() writes to freed memory, which is only safe with the
> GENERIC mode (as it uses quarantine). For other modes, this test corrupts
> kernel memory, which might result in a crash.
>
> Only enable kmalloc_uaf_memset() for the GENERIC mode.
>
> Signed-off-by: Andrey Konovalov <andreyknvl@gmail.com>

Acked-by: Marco Elver <elver@google.com>


> ---
>  lib/test_kasan.c | 6 ++++++
>  1 file changed, 6 insertions(+)
>
> diff --git a/lib/test_kasan.c b/lib/test_kasan.c
> index 0b5698cd7d1d..efd0da5c750f 100644
> --- a/lib/test_kasan.c
> +++ b/lib/test_kasan.c
> @@ -528,6 +528,12 @@ static void kmalloc_uaf_memset(struct kunit *test)
>         char *ptr;
>         size_t size = 33;
>
> +       /*
> +        * Only generic KASAN uses quarantine, which is required to avoid a
> +        * kernel memory corruption this test causes.
> +        */
> +       KASAN_TEST_NEEDS_CONFIG_ON(test, CONFIG_KASAN_GENERIC);
> +
>         ptr = kmalloc(size, GFP_KERNEL);
>         KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
>
> --
> 2.25.1