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kasan: add compiler barriers to KUNIT_EXPECT_KASAN_FAIL 

It might not be obvious to the compiler that the expression must be
executed between writing and reading to fail_data. In this case, the
compiler might reorder or optimize away some of the accesses, and
the tests will fail.

Add compiler barriers around the expression in KUNIT_EXPECT_KASAN_FAIL
and use READ/WRITE_ONCE() for accessing fail_data fields.

Link: https://linux-review.googlesource.com/id/I046079f48641a1d36fe627fc8827a9249102fd50
Link: https://lkml.kernel.org/r/6f11596f367d8ae8f71d800351e9a5d91eda19f6.1610733117.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Marco Elver <elver@google.com>
Reviewed-by: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Branislav Rankov <Branislav.Rankov@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Kevin Brodsky <kevin.brodsky@arm.com>
Cc: Peter Collingbourne <pcc@google.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
master
Andrey Konovalov 2021-02-24 12:05:34 -08:00 committed by Linus Torvalds
parent 5d92bdffd2
commit 2e4bde6a1e
2 changed files with 13 additions and 6 deletions
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17
lib/test_kasan.c
View File

@ -68,23 +68,30 @@ static void kasan_test_exit(struct kunit *test)
* normally auto-disabled. When this happens, this test handler reenables
* tag checking. As tag checking can be only disabled or enabled per CPU, this
* handler disables migration (preemption).
*
* Since the compiler doesn't see that the expression can change the fail_data
* 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.
*/
#define KUNIT_EXPECT_KASAN_FAIL(test, expression) do { \
if (IS_ENABLED(CONFIG_KASAN_HW_TAGS)) \
migrate_disable(); \
fail_data.report_expected = true; \
fail_data.report_found = false; \
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(); \
KUNIT_EXPECT_EQ(test, \
fail_data.report_expected, \
fail_data.report_found); \
READ_ONCE(fail_data.report_expected), \
READ_ONCE(fail_data.report_found)); \
if (IS_ENABLED(CONFIG_KASAN_HW_TAGS)) { \
if (fail_data.report_found) \
if (READ_ONCE(fail_data.report_found)) \
kasan_enable_tagging(); \
migrate_enable(); \
} \

2
mm/kasan/report.c
View File

@ -331,7 +331,7 @@ static void kasan_update_kunit_status(struct kunit *cur_test)
}
kasan_data = (struct kunit_kasan_expectation *)resource->data;
kasan_data->report_found = true;
WRITE_ONCE(kasan_data->report_found, true);
kunit_put_resource(resource);
}
#endif /* IS_ENABLED(CONFIG_KUNIT) */