Re: [PATCH v3] kasan: add kunit tests for kmalloc_track_caller, kmalloc_node_track_caller

[Andrey Konovalov]

On Mon, Oct 14, 2024 at 9:08 PM Nihar Chaithanya
<niharchaithanya@xxxxxxxxx> wrote:
>
> The Kunit tests for kmalloc_track_caller and kmalloc_node_track_caller
> were missing in kasan_test_c.c, which check that these functions poison
> the memory properly.
>
> Add a Kunit test:
> -> kmalloc_tracker_caller_oob_right(): This includes out-of-bounds
>    access test for kmalloc_track_caller and kmalloc_node_track_caller.
>
> Signed-off-by: Nihar Chaithanya <niharchaithanya@xxxxxxxxx>
> Fixes: https://bugzilla.kernel.org/show_bug.cgi?id=216509
> ---
> v1->v2: Simplified the three separate out-of-bounds tests to a single
> test for kmalloc_track_caller.
>
> v2->v3: Used the same size for both the test cases.
>
> Link to v1: https://lore.kernel.org/all/20241013172912.1047136-1-niharchaithanya@xxxxxxxxx/
> Link to v2: https://lore.kernel.org/all/20241014041130.1768674-1-niharchaithanya@xxxxxxxxx/
>
>  mm/kasan/kasan_test_c.c | 31 +++++++++++++++++++++++++++++++
>  1 file changed, 31 insertions(+)
>
> diff --git a/mm/kasan/kasan_test_c.c b/mm/kasan/kasan_test_c.c
> index a181e4780d9d..7e7076e71de0 100644
> --- a/mm/kasan/kasan_test_c.c
> +++ b/mm/kasan/kasan_test_c.c
> @@ -213,6 +213,36 @@ static void kmalloc_node_oob_right(struct kunit *test)
>         kfree(ptr);
>  }
>
> +static void kmalloc_track_caller_oob_right(struct kunit *test)
> +{
> +       char *ptr;
> +       size_t size = 128 - KASAN_GRANULE_SIZE;
> +
> +       /*
> +        * Check that KASAN detects out-of-bounds access for object allocated via
> +        * kmalloc_track_caller().
> +        */
> +       ptr = kmalloc_track_caller(size, GFP_KERNEL);
> +       KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
> +
> +       OPTIMIZER_HIDE_VAR(ptr);
> +       KUNIT_EXPECT_KASAN_FAIL(test, ptr[size] = 'y');
> +
> +       kfree(ptr);
> +
> +       /*
> +        * Check that KASAN detects out-of-bounds access for object allocated via
> +        * kmalloc_node_track_caller().
> +        */
> +       ptr = kmalloc_node_track_caller(size, GFP_KERNEL, 0);
> +       KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
> +
> +       OPTIMIZER_HIDE_VAR(ptr);
> +       KUNIT_EXPECT_KASAN_FAIL(test, ptr[size] = 'y');
> +
> +       kfree(ptr);
> +}
> +
>  /*
>   * Check that KASAN detects an out-of-bounds access for a big object allocated
>   * via kmalloc(). But not as big as to trigger the page_alloc fallback.
> @@ -1958,6 +1988,7 @@ static struct kunit_case kasan_kunit_test_cases[] = {
>         KUNIT_CASE(kmalloc_oob_right),
>         KUNIT_CASE(kmalloc_oob_left),
>         KUNIT_CASE(kmalloc_node_oob_right),
> +       KUNIT_CASE(kmalloc_track_caller_oob_right),
>         KUNIT_CASE(kmalloc_big_oob_right),
>         KUNIT_CASE(kmalloc_large_oob_right),
>         KUNIT_CASE(kmalloc_large_uaf),
> --
> 2.34.1
>

Reviewed-by: Andrey Konovalov <andreyknvl@xxxxxxxxx>

Thank you!