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Date: Sat, 5 Jun 2021 17:55:30 -0700
From: David Gow <davidgow@...gle.com>
To: Andrey Ryabinin <ryabinin.a.a@...il.com>,
Dmitry Vyukov <dvyukov@...gle.com>,
Daniel Axtens <dja@...ens.net>,
Brendan Higgins <brendanhiggins@...gle.com>
Cc: David Gow <davidgow@...gle.com>, kasan-dev@...glegroups.com,
kunit-dev@...glegroups.com, linux-kernel@...r.kernel.org,
Jonathan Corbet <corbet@....net>, linux-doc@...r.kernel.org
Subject: [PATCH v3] kasan: test: Improve failure message in KUNIT_EXPECT_KASAN_FAIL()
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@...gle.com>
---
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
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