linux-kernel - Re: [PATCH 4/8] kasan: test: disable kmalloc_memmove_invalid_size for HW

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Date:   Thu, 12 Aug 2021 10:57:25 +0200
From:   Marco Elver <elver@...gle.com>
To:     andrey.konovalov@...ux.dev
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Andrey Konovalov <andreyknvl@...il.com>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Alexander Potapenko <glider@...gle.com>,
        kasan-dev@...glegroups.com, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4/8] kasan: test: disable kmalloc_memmove_invalid_size for HW_TAGS

On Wed, 11 Aug 2021 at 21:21, <andrey.konovalov@...ux.dev> wrote:
> From: Andrey Konovalov <andreyknvl@...il.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@...il.com>

Reviewed-by: Marco Elver <elver@...gle.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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