[PATCH mm] kasan: fix array-bounds warnings in tests

[andrey . konovalov]

From: Andrey Konovalov <andreyknvl@xxxxxxxxxx>

GCC's -Warray-bounds option detects out-of-bounds accesses to
statically-sized allocations in krealloc out-of-bounds tests.

Use OPTIMIZER_HIDE_VAR to suppress the warning.

Also change kmalloc_memmove_invalid_size to use OPTIMIZER_HIDE_VAR
instead of a volatile variable.

Reported-by: kernel test robot <lkp@xxxxxxxxx>
Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
---
 mm/kasan/kasan_test.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/mm/kasan/kasan_test.c b/mm/kasan/kasan_test.c
index 71cb402c404f..1d51efe131db 100644
--- a/mm/kasan/kasan_test.c
+++ b/mm/kasan/kasan_test.c
@@ -324,6 +324,9 @@ static void krealloc_more_oob_helper(struct kunit *test,
 	char *ptr1, *ptr2;
 	size_t middle;
 
+	OPTIMIZER_HIDE_VAR(size1);
+	OPTIMIZER_HIDE_VAR(size2);
+
 	KUNIT_ASSERT_LT(test, size1, size2);
 	middle = size1 + (size2 - size1) / 2;
 
@@ -356,6 +359,9 @@ static void krealloc_less_oob_helper(struct kunit *test,
 	char *ptr1, *ptr2;
 	size_t middle;
 
+	OPTIMIZER_HIDE_VAR(size1);
+	OPTIMIZER_HIDE_VAR(size2);
+
 	KUNIT_ASSERT_LT(test, size2, size1);
 	middle = size2 + (size1 - size2) / 2;
 
@@ -578,13 +584,14 @@ static void kmalloc_memmove_invalid_size(struct kunit *test)
 {
 	char *ptr;
 	size_t size = 64;
-	volatile size_t invalid_size = size;
+	size_t invalid_size = size;
 
 	ptr = kmalloc(size, GFP_KERNEL);
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
 
 	memset((char *)ptr, 0, 64);
 	OPTIMIZER_HIDE_VAR(ptr);
+	OPTIMIZER_HIDE_VAR(invalid_size);
 	KUNIT_EXPECT_KASAN_FAIL(test,
 		memmove((char *)ptr, (char *)ptr + 4, invalid_size));
 	kfree(ptr);
-- 
2.25.1