Re: [PATCH v3 4/4] KASAN: Testing Documentation

[Dmitry Vyukov]

On Wed, Apr 1, 2020 at 8:09 PM Patricia Alfonso <trishalfonso@xxxxxxxxxx> wrote:
>
> Include documentation on how to test KASAN using CONFIG_TEST_KASAN and
> CONFIG_TEST_KASAN_USER.
>
> Signed-off-by: Patricia Alfonso <trishalfonso@xxxxxxxxxx>

Reviewed-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx>

> ---
>  Documentation/dev-tools/kasan.rst | 70 +++++++++++++++++++++++++++++++
>  1 file changed, 70 insertions(+)
>
> diff --git a/Documentation/dev-tools/kasan.rst b/Documentation/dev-tools/kasan.rst
> index c652d740735d..287ba063d9f6 100644
> --- a/Documentation/dev-tools/kasan.rst
> +++ b/Documentation/dev-tools/kasan.rst
> @@ -281,3 +281,73 @@ unmapped. This will require changes in arch-specific code.
>
>  This allows ``VMAP_STACK`` support on x86, and can simplify support of
>  architectures that do not have a fixed module region.
> +
> +CONFIG_TEST_KASAN & CONFIG_TEST_KASAN_USER
> +-------------------------------------------
> +
> +``CONFIG_TEST_KASAN`` utilizes the KUnit Test Framework for testing.
> +This means each test focuses on a small unit of functionality and
> +there are a few ways these tests can be run.
> +
> +Each test will print the KASAN report if an error is detected and then
> +print the number of the test and the status of the test:
> +
> +pass::
> +
> +        ok 28 - kmalloc_double_kzfree
> +or, if kmalloc failed::
> +
> +        # kmalloc_large_oob_right: ASSERTION FAILED at lib/test_kasan.c:163
> +        Expected ptr is not null, but is
> +        not ok 4 - kmalloc_large_oob_right
> +or, if a KASAN report was expected, but not found::
> +
> +        # kmalloc_double_kzfree: EXPECTATION FAILED at lib/test_kasan.c:629
> +        Expected kasan_data->report_expected == kasan_data->report_found, but
> +        kasan_data->report_expected == 1
> +        kasan_data->report_found == 0
> +        not ok 28 - kmalloc_double_kzfree
> +
> +All test statuses are tracked as they run and an overall status will
> +be printed at the end::
> +
> +        ok 1 - kasan_kunit_test
> +
> +or::
> +
> +        not ok 1 - kasan_kunit_test
> +
> +(1) Loadable Module
> +~~~~~~~~~~~~~~~~~~~~
> +
> +With ``CONFIG_KUNIT`` built-in, ``CONFIG_TEST_KASAN`` can be built as
> +a loadable module and run on any architecture that supports KASAN
> +using something like insmod or modprobe.
> +
> +(2) Built-In
> +~~~~~~~~~~~~~
> +
> +With ``CONFIG_KUNIT`` built-in, ``CONFIG_TEST_KASAN`` can be built-in
> +on any architecure that supports KASAN. These and any other KUnit
> +tests enabled will run and print the results at boot as a late-init
> +call.
> +
> +(3) Using kunit_tool
> +~~~~~~~~~~~~~~~~~~~~~
> +
> +With ``CONFIG_KUNIT`` and ``CONFIG_TEST_KASAN`` built-in, we can also
> +use kunit_tool to see the results of these along with other KUnit
> +tests in a more readable way. This will not print the KASAN reports
> +of tests that passed. Use `KUnit documentation <https://www.kernel.org/doc/html/latest/dev-tools/kunit/index.html>`_ for more up-to-date
> +information on kunit_tool.
> +
> +.. _KUnit: https://www.kernel.org/doc/html/latest/dev-tools/kunit/index.html
> +
> +``CONFIG_TEST_KASAN_USER`` is a set of KASAN tests that could not be
> +converted to KUnit. These tests can be run only as a module with
> +``CONFIG_TEST_KASAN_USER`` built as a loadable module and
> +``CONFIG_KASAN`` built-in. The type of error expected and the
> +function being run is printed before the expression expected to give
> +an error. Then the error is printed, if found, and that test
> +should be interpretted to pass only if the error was the one expected
> +by the test.
> --
> 2.26.0.rc2.310.g2932bb562d-goog
>