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authorAndrey Konovalov <andreyknvl@google.com>2021-02-24 12:05:34 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2021-02-24 13:38:31 -0800
commit2e4bde6a1e3a3feb8511685b8c97be668728eefb (patch)
treef8decf829afbdffe9c7dbf096f96a9d4917172be /lib
parent5d92bdffd2d53f98de683229c0ad7d028703fdba (diff)
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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>
Diffstat (limited to 'lib')
-rw-r--r--lib/test_kasan.c17
1 files changed, 12 insertions, 5 deletions
diff --git a/lib/test_kasan.c b/lib/test_kasan.c
index 502709db41c0..603fd7937b94 100644
--- a/lib/test_kasan.c
+++ b/lib/test_kasan.c
@@ -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(); \
} \