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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.

Link: https://lkml.kernel.org/r/20210606005531.165954-1-davidgow@google.com
Signed-off-by: David Gow <davidgow@google.com>
Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>
Reviewed-by: Marco Elver <elver@google.com>
Acked-by: Brendan Higgins <brendanhiggins@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Daniel Axtens <dja@axtens.net>
Cc: David Gow <davidgow@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
David Gow 2021-06-28 19:40:36 -07:00 committed by Linus Torvalds
parent 336abff6e8
commit 3ff16d30f5
3 changed files with 9 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
Documentation/dev-tools/kasan.rst
View File

@ -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::

1
include/linux/kasan.h
View File

@ -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;
};

11
lib/test_kasan.c
View File

@ -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 { \