[PATCH v2] kasan: fix more unit tests with CONFIG_UBSAN_LOCAL_BOUNDS enabled

[Peter Collingbourne <pcc@google.com>]

This is a followup to commit f649dc0e0d7b ("kasan: fix unit tests
with CONFIG_UBSAN_LOCAL_BOUNDS enabled") that fixes tests that fail
as a result of __alloc_size annotations being added to the kernel
allocator functions.

Link: https://linux-review.googlesource.com/id/I4334cafc5db600fda5cebb851b2ee9fd09fb46cc
Signed-off-by: Peter Collingbourne <pcc@google.com>
Cc: <stable@vger.kernel.org> # 5.16.x
Fixes: c37495d6254c ("slab: add __alloc_size attributes for better bounds checking")
---
v2:
- use OPTIMIZER_HIDE_VAR instead of volatile

 lib/test_kasan.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/lib/test_kasan.c b/lib/test_kasan.c
index 26a5c9007653..7c3dfb569445 100644
--- a/lib/test_kasan.c
+++ b/lib/test_kasan.c
@@ -185,6 +185,7 @@ static void kmalloc_pagealloc_oob_right(struct kunit *test)
 	ptr = kmalloc(size, GFP_KERNEL);
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
 
+	OPTIMIZER_HIDE_VAR(ptr);
 	KUNIT_EXPECT_KASAN_FAIL(test, ptr[size + OOB_TAG_OFF] = 0);
 
 	kfree(ptr);
@@ -295,6 +296,7 @@ static void krealloc_more_oob_helper(struct kunit *test,
 		KUNIT_EXPECT_KASAN_FAIL(test, ptr2[size2] = 'x');
 
 	/* For all modes first aligned offset after size2 must be inaccessible. */
+	OPTIMIZER_HIDE_VAR(ptr2);
 	KUNIT_EXPECT_KASAN_FAIL(test,
 		ptr2[round_up(size2, KASAN_GRANULE_SIZE)] = 'x');
 
@@ -319,6 +321,8 @@ static void krealloc_less_oob_helper(struct kunit *test,
 	/* Must be accessible for all modes. */
 	ptr2[size2 - 1] = 'x';
 
+	OPTIMIZER_HIDE_VAR(ptr2);
+
 	/* Generic mode is precise, so unaligned size2 must be inaccessible. */
 	if (IS_ENABLED(CONFIG_KASAN_GENERIC))
 		KUNIT_EXPECT_KASAN_FAIL(test, ptr2[size2] = 'x');
-- 
2.35.1.473.g83b2b277ed-goog