Messages in this thread | | | From | David Gow <> | Date | Fri, 4 Jun 2021 16:34:00 +0800 | Subject | Re: [PATCH] kasan: test: Improve failure message in KUNIT_EXPECT_KASAN_FAIL() |
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On Fri, Jun 4, 2021 at 3:55 PM Marco Elver <elver@google.com> wrote: > > On Fri, 4 Jun 2021 at 07:26, 'David Gow' via kasan-dev > <kasan-dev@googlegroups.com> 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 test > > report_expected to 'true'), and print a better failure message with > > KUNIT_FAIL() > > > > Beforehand, a failure in: > > KUNIT_EXPECT_KASAN_FAIL(test, ((volatile char *)area)[3100]); > > would 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 > > > > Signed-off-by: David Gow <davidgow@google.com> > > --- > > > > Stumbled across this because the vmalloc_oob test is failing (i.e., > > KASAN isn't picking up an error) under qemu on my system, and the > > message above was horrifying. (I'll file a Bugzilla bug for the test > > failure today.) > > > > Cheers, > > -- David > > > > lib/test_kasan.c | 8 +++++--- > > 1 file changed, 5 insertions(+), 3 deletions(-) > > > > diff --git a/lib/test_kasan.c b/lib/test_kasan.c > > index cacbbbdef768..deda13c9d9ff 100644 > > --- a/lib/test_kasan.c > > +++ b/lib/test_kasan.c > > @@ -98,9 +98,11 @@ static void kasan_test_exit(struct kunit *test) > > barrier(); \ > > expression; \ > > barrier(); \ > > - KUNIT_EXPECT_EQ(test, \ > > - READ_ONCE(fail_data.report_expected), \ > > What do we have fail_data.report_expected for? Could we remove it now? > I think it's unused now. >
I thought this was being used in kasan_update_kunit_status() (in mm/kasan/report.c), but it looks like I was mistaken. We should be able to get rid of it, then/
> > - READ_ONCE(fail_data.report_found)); \ > > + if (READ_ONCE(fail_data.report_found) == false) { \ > > if (!READ_ONCE(fail_data.report_found)) { > ? >
I'll change this for v2.
> > + KUNIT_FAIL(test, KUNIT_SUBTEST_INDENT "KASAN failure " \ > > + "expected in \"" #expression \ > > + "\", but none occurred"); \ > > + } \ > > Thanks, > -- Marco
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