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kasan: detect false-positives in tests 

Currently, KASAN-KUnit tests can check that a particular annotated part of
code causes a KASAN report.  However, they do not check that no unwanted
reports happen between the annotated parts.

This patch implements these checks.

It is done by setting report_data.report_found to false in
kasan_test_init() and at the end of KUNIT_EXPECT_KASAN_FAIL() and then
checking that it remains false at the beginning of
KUNIT_EXPECT_KASAN_FAIL() and in kasan_test_exit().

kunit_add_named_resource() call is moved to kasan_test_init(), and the
value of fail_data.report_expected is kept as false in between
KUNIT_EXPECT_KASAN_FAIL() annotations for consistency.

Link: https://lkml.kernel.org/r/48079c52cc329fbc52f4386996598d58022fb872.1617207873.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Marco Elver <elver@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Andrey Konovalov 2021-04-29 23:00:49 -07:00 committed by Linus Torvalds
parent 23f61f0fe1
commit 99734b535d
1 changed files with 29 additions and 26 deletions
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55
lib/test_kasan.c
View File

@ -54,6 +54,10 @@ 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;
}
@ -61,6 +65,7 @@ static void kasan_test_exit(struct kunit *test)
{
kasan_set_tagging_report_once(true);
kasan_restore_multi_shot(multishot);
KUNIT_EXPECT_FALSE(test, fail_data.report_found);
}
/**
@ -78,33 +83,31 @@ static void kasan_test_exit(struct kunit *test)
* fields, it can reorder or optimize away the accesses to those fields.
* Use READ/WRITE_ONCE() for the accesses and compiler barriers around the
* expression to prevent that.
*
* In between KUNIT_EXPECT_KASAN_FAIL checks, fail_data.report_found is kept as
* false. This allows detecting KASAN reports that happen outside of the checks
* by asserting !fail_data.report_found at the start of KUNIT_EXPECT_KASAN_FAIL
* and in kasan_test_exit.
*/
#define KUNIT_EXPECT_KASAN_FAIL(test, expression) do { \
if (IS_ENABLED(CONFIG_KASAN_HW_TAGS) && \
!kasan_async_mode_enabled()) \
migrate_disable(); \
WRITE_ONCE(fail_data.report_expected, true); \
WRITE_ONCE(fail_data.report_found, false); \
kunit_add_named_resource(test, \
NULL, \
NULL, \
&resource, \
"kasan_data", &fail_data); \
barrier(); \
expression; \
barrier(); \
if (kasan_async_mode_enabled()) \
kasan_force_async_fault(); \
barrier(); \
KUNIT_EXPECT_EQ(test, \
READ_ONCE(fail_data.report_expected), \
READ_ONCE(fail_data.report_found)); \
if (IS_ENABLED(CONFIG_KASAN_HW_TAGS) && \
!kasan_async_mode_enabled()) { \
if (READ_ONCE(fail_data.report_found)) \
kasan_enable_tagging_sync(); \
migrate_enable(); \
} \
#define KUNIT_EXPECT_KASAN_FAIL(test, expression) do { \
if (IS_ENABLED(CONFIG_KASAN_HW_TAGS) && \
!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 (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 { \