On Sun, 6 Jun 2021 at 11:57, Andrey Konovalov <andreyknvl@xxxxxxxxx> wrote: > > On Sun, Jun 6, 2021 at 3:55 AM 'David Gow' via kasan-dev > <kasan-dev@xxxxxxxxxxxxxxxx> wrote: > > > > The KUNIT_EXPECT_KASAN_FAIL() macro currently uses KUNIT_EXPECT_EQ() to > > compare fail_data.report_expected and fail_data.report_found. This > > always gave a somewhat useless error message on failure, but the > > addition of extra compile-time checking with READ_ONCE() has caused it > > to get much longer, and be truncated before anything useful is displayed. > > > > Instead, just check fail_data.report_found by hand (we've just set > > report_expected to 'true'), and print a better failure message with > > KUNIT_FAIL(). Because of this, report_expected is no longer used > > anywhere, and can be removed. > > > > Beforehand, a failure in: > > KUNIT_EXPECT_KASAN_FAIL(test, ((volatile char *)area)[3100]); > > would have looked like: > > [22:00:34] [FAILED] vmalloc_oob > > [22:00:34] # vmalloc_oob: EXPECTATION FAILED at lib/test_kasan.c:991 > > [22:00:34] Expected ({ do { extern void __compiletime_assert_705(void) __attribute__((__error__("Unsupported access size for {READ,WRITE}_ONCE()."))); if (!((sizeof(fail_data.report_expected) == sizeof(char) || sizeof(fail_data.repp > > [22:00:34] not ok 45 - vmalloc_oob > > > > With this change, it instead looks like: > > [22:04:04] [FAILED] vmalloc_oob > > [22:04:04] # vmalloc_oob: EXPECTATION FAILED at lib/test_kasan.c:993 > > [22:04:04] KASAN failure expected in "((volatile char *)area)[3100]", but none occurred > > [22:04:04] not ok 45 - vmalloc_oob > > > > Also update the example failure in the documentation to reflect this. > > > > Signed-off-by: David Gow <davidgow@xxxxxxxxxx> > > --- > > > > Changes since v2: > > https://lkml.org/lkml/2021/6/4/1264 > > - Update the example error in the documentation > > > > Changes since v1: > > https://groups.google.com/g/kasan-dev/c/CbabdwoXGlE > > - Remove fail_data.report_expected now that it's unused. > > - Use '!' instead of '== false' in the comparison. > > - Minor typo fixes in the commit message. > > > > The test failure being used as an example is tracked in: > > https://bugzilla.kernel.org/show_bug.cgi?id=213335 > > > > > > > > Documentation/dev-tools/kasan.rst | 9 ++++----- > > include/linux/kasan.h | 1 - > > lib/test_kasan.c | 11 +++++------ > > 3 files changed, 9 insertions(+), 12 deletions(-) > > > > diff --git a/Documentation/dev-tools/kasan.rst b/Documentation/dev-tools/kasan.rst > > index d3f335ffc751..83ec4a556c19 100644 > > --- a/Documentation/dev-tools/kasan.rst > > +++ b/Documentation/dev-tools/kasan.rst > > @@ -447,11 +447,10 @@ When a test fails due to a failed ``kmalloc``:: > > > > When a test fails due to a missing KASAN report:: > > > > - # 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 > > + # kmalloc_double_kzfree: EXPECTATION FAILED at lib/test_kasan.c:974 > > + KASAN failure expected in "kfree_sensitive(ptr)", but none occurred > > + not ok 44 - kmalloc_double_kzfree > > + > > > > At the end the cumulative status of all KASAN tests is printed. On success:: > > > > diff --git a/include/linux/kasan.h b/include/linux/kasan.h > > index b1678a61e6a7..18cd5ec2f469 100644 > > --- a/include/linux/kasan.h > > +++ b/include/linux/kasan.h > > @@ -17,7 +17,6 @@ struct task_struct; > > > > /* kasan_data struct is used in KUnit tests for KASAN expected failures */ > > struct kunit_kasan_expectation { > > - bool report_expected; > > bool report_found; > > }; > > > > diff --git a/lib/test_kasan.c b/lib/test_kasan.c > > index cacbbbdef768..44e08f4d9c52 100644 > > --- a/lib/test_kasan.c > > +++ b/lib/test_kasan.c > > @@ -55,7 +55,6 @@ static int kasan_test_init(struct kunit *test) > > multishot = kasan_save_enable_multi_shot(); > > kasan_set_tagging_report_once(false); > > fail_data.report_found = false; > > - fail_data.report_expected = false; > > kunit_add_named_resource(test, NULL, NULL, &resource, > > "kasan_data", &fail_data); > > return 0; > > @@ -94,20 +93,20 @@ static void kasan_test_exit(struct kunit *test) > > !kasan_async_mode_enabled()) \ > > migrate_disable(); \ > > KUNIT_EXPECT_FALSE(test, READ_ONCE(fail_data.report_found)); \ > > - WRITE_ONCE(fail_data.report_expected, true); \ > > barrier(); \ > > expression; \ > > barrier(); \ > > - KUNIT_EXPECT_EQ(test, \ > > - READ_ONCE(fail_data.report_expected), \ > > - READ_ONCE(fail_data.report_found)); \ > > + if (!READ_ONCE(fail_data.report_found)) { \ > > + KUNIT_FAIL(test, KUNIT_SUBTEST_INDENT "KASAN failure " \ > > + "expected in \"" #expression \ > > + "\", but none occurred"); \ > > + } \ > > if (IS_ENABLED(CONFIG_KASAN_HW_TAGS)) { \ > > if (READ_ONCE(fail_data.report_found)) \ > > kasan_enable_tagging_sync(); \ > > migrate_enable(); \ > > } \ > > WRITE_ONCE(fail_data.report_found, false); \ > > - WRITE_ONCE(fail_data.report_expected, false); \ > > } while (0) > > > > #define KASAN_TEST_NEEDS_CONFIG_ON(test, config) do { \ > > -- > > 2.32.0.rc1.229.g3e70b5a671-goog > > Reviewed-by: Andrey Konovalov <andreyknvl@xxxxxxxxx> Reviewed-by: Marco Elver <elver@xxxxxxxxxx>