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In-Reply-To: <408c63e4a0353633a13403aab4ff25a505e03d93.1628709663.git.andreyknvl@gmail.com>
From:   Marco Elver <elver@google.com>
Date:   Thu, 12 Aug 2021 10:57:25 +0200
Message-ID: <CANpmjNMo0p+pQS=_rL37RpPPdzLFDqYw8D3V+qeCt3_jDu+anA@mail.gmail.com>
Subject: Re: [PATCH 4/8] kasan: test: disable kmalloc_memmove_invalid_size for HW_TAGS
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>
>
> The HW_TAGS mode doesn't check memmove for negative size. As a result,
> the kmalloc_memmove_invalid_size test corrupts memory, which can result
> in a crash.
>
> Disable this test with HW_TAGS KASAN.
>
> Signed-off-by: Andrey Konovalov <andreyknvl@gmail.com>

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


> ---
>  lib/test_kasan.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/lib/test_kasan.c b/lib/test_kasan.c
> index fd00cd35e82c..0b5698cd7d1d 100644
> --- a/lib/test_kasan.c
> +++ b/lib/test_kasan.c
> @@ -495,11 +495,17 @@ static void kmalloc_memmove_invalid_size(struct kunit *test)
>         size_t size = 64;
>         volatile size_t invalid_size = -2;
>
> +       /*
> +        * Hardware tag-based mode doesn't check memmove for negative size.
> +        * As a result, this test introduces a side-effect memory corruption,
> +        * which can result in a crash.
> +        */
> +       KASAN_TEST_NEEDS_CONFIG_OFF(test, CONFIG_KASAN_HW_TAGS);
> +
>         ptr = kmalloc(size, GFP_KERNEL);
>         KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
>
>         memset((char *)ptr, 0, 64);
> -
>         KUNIT_EXPECT_KASAN_FAIL(test,
>                 memmove((char *)ptr, (char *)ptr + 4, invalid_size));
>         kfree(ptr);
> --
> 2.25.1
>
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