[PATCH 3/8] kasan: test: avoid corrupting memory via memset

[andrey.konovalov@linux.dev]

From: Andrey Konovalov <andreyknvl@gmail.com>

kmalloc_oob_memset_*() tests do writes past the allocated objects.
As the result, they corrupt memory, which might lead to crashes with the
HW_TAGS mode, as it neither uses quarantine nor redzones.

Adjust the tests to only write memory within the aligned kmalloc objects.

Signed-off-by: Andrey Konovalov <andreyknvl@gmail.com>
---
 lib/test_kasan.c | 22 +++++++++++-----------
 1 file changed, 11 insertions(+), 11 deletions(-)

diff --git a/lib/test_kasan.c b/lib/test_kasan.c
index c82a82eb5393..fd00cd35e82c 100644
--- a/lib/test_kasan.c
+++ b/lib/test_kasan.c
@@ -431,61 +431,61 @@ static void kmalloc_uaf_16(struct kunit *test)
 static void kmalloc_oob_memset_2(struct kunit *test)
 {
 	char *ptr;
-	size_t size = 8;
+	size_t size = 128 - KASAN_GRANULE_SIZE;
 
 	ptr = kmalloc(size, GFP_KERNEL);
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
 
-	KUNIT_EXPECT_KASAN_FAIL(test, memset(ptr + 7 + OOB_TAG_OFF, 0, 2));
+	KUNIT_EXPECT_KASAN_FAIL(test, memset(ptr + size, 0, 2));
 	kfree(ptr);
 }
 
 static void kmalloc_oob_memset_4(struct kunit *test)
 {
 	char *ptr;
-	size_t size = 8;
+	size_t size = 128 - KASAN_GRANULE_SIZE;
 
 	ptr = kmalloc(size, GFP_KERNEL);
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
 
-	KUNIT_EXPECT_KASAN_FAIL(test, memset(ptr + 5 + OOB_TAG_OFF, 0, 4));
+	KUNIT_EXPECT_KASAN_FAIL(test, memset(ptr + size, 0, 4));
 	kfree(ptr);
 }
 
-
 static void kmalloc_oob_memset_8(struct kunit *test)
 {
 	char *ptr;
-	size_t size = 8;
+	size_t size = 128 - KASAN_GRANULE_SIZE;
 
 	ptr = kmalloc(size, GFP_KERNEL);
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
 
-	KUNIT_EXPECT_KASAN_FAIL(test, memset(ptr + 1 + OOB_TAG_OFF, 0, 8));
+	KUNIT_EXPECT_KASAN_FAIL(test, memset(ptr + size, 0, 8));
 	kfree(ptr);
 }
 
 static void kmalloc_oob_memset_16(struct kunit *test)
 {
 	char *ptr;
-	size_t size = 16;
+	size_t size = 128 - KASAN_GRANULE_SIZE;
 
 	ptr = kmalloc(size, GFP_KERNEL);
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
 
-	KUNIT_EXPECT_KASAN_FAIL(test, memset(ptr + 1 + OOB_TAG_OFF, 0, 16));
+	KUNIT_EXPECT_KASAN_FAIL(test, memset(ptr + size, 0, 16));
 	kfree(ptr);
 }
 
 static void kmalloc_oob_in_memset(struct kunit *test)
 {
 	char *ptr;
-	size_t size = 666;
+	size_t size = 128 - KASAN_GRANULE_SIZE;
 
 	ptr = kmalloc(size, GFP_KERNEL);
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
 
-	KUNIT_EXPECT_KASAN_FAIL(test, memset(ptr, 0, size + 5 + OOB_TAG_OFF));
+	KUNIT_EXPECT_KASAN_FAIL(test,
+				memset(ptr, 0, size + KASAN_GRANULE_SIZE));
 	kfree(ptr);
 }
 
-- 
2.25.1