[PATCH v2 14/16] kasan: Remove ksize()-related tests

[Kees Cook]

In preparation for no longer unpoisoning in ksize(), remove the behavioral
self-tests for ksize().

Cc: Andrey Ryabinin <ryabinin.a.a@xxxxxxxxx>
Cc: Alexander Potapenko <glider@xxxxxxxxxx>
Cc: Andrey Konovalov <andreyknvl@xxxxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Vincenzo Frascino <vincenzo.frascino@xxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: kasan-dev@xxxxxxxxxxxxxxxx
Cc: linux-mm@xxxxxxxxx
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
---
 lib/test_kasan.c  | 42 ------------------------------------------
 mm/kasan/shadow.c |  4 +---
 2 files changed, 1 insertion(+), 45 deletions(-)

diff --git a/lib/test_kasan.c b/lib/test_kasan.c
index 58c1b01ccfe2..bdd0ced8f8d7 100644
--- a/lib/test_kasan.c
+++ b/lib/test_kasan.c
@@ -753,46 +753,6 @@ static void kasan_global_oob_left(struct kunit *test)
 	KUNIT_EXPECT_KASAN_FAIL(test, *(volatile char *)p);
 }
 
-/* Check that ksize() makes the whole object accessible. */
-static void ksize_unpoisons_memory(struct kunit *test)
-{
-	char *ptr;
-	size_t size = 123, real_size;
-
-	ptr = kmalloc(size, GFP_KERNEL);
-	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
-	real_size = ksize(ptr);
-
-	OPTIMIZER_HIDE_VAR(ptr);
-
-	/* This access shouldn't trigger a KASAN report. */
-	ptr[size] = 'x';
-
-	/* This one must. */
-	KUNIT_EXPECT_KASAN_FAIL(test, ((volatile char *)ptr)[real_size]);
-
-	kfree(ptr);
-}
-
-/*
- * Check that a use-after-free is detected by ksize() and via normal accesses
- * after it.
- */
-static void ksize_uaf(struct kunit *test)
-{
-	char *ptr;
-	int size = 128 - KASAN_GRANULE_SIZE;
-
-	ptr = kmalloc(size, GFP_KERNEL);
-	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
-	kfree(ptr);
-
-	OPTIMIZER_HIDE_VAR(ptr);
-	KUNIT_EXPECT_KASAN_FAIL(test, ksize(ptr));
-	KUNIT_EXPECT_KASAN_FAIL(test, ((volatile char *)ptr)[0]);
-	KUNIT_EXPECT_KASAN_FAIL(test, ((volatile char *)ptr)[size]);
-}
-
 static void kasan_stack_oob(struct kunit *test)
 {
 	char stack_array[10];
@@ -1392,8 +1352,6 @@ static struct kunit_case kasan_kunit_test_cases[] = {
 	KUNIT_CASE(kasan_stack_oob),
 	KUNIT_CASE(kasan_alloca_oob_left),
 	KUNIT_CASE(kasan_alloca_oob_right),
-	KUNIT_CASE(ksize_unpoisons_memory),
-	KUNIT_CASE(ksize_uaf),
 	KUNIT_CASE(kmem_cache_double_free),
 	KUNIT_CASE(kmem_cache_invalid_free),
 	KUNIT_CASE(kmem_cache_double_destroy),
diff --git a/mm/kasan/shadow.c b/mm/kasan/shadow.c
index 0e3648b603a6..0895c73e9b69 100644
--- a/mm/kasan/shadow.c
+++ b/mm/kasan/shadow.c
@@ -124,9 +124,7 @@ void kasan_unpoison(const void *addr, size_t size, bool init)
 	addr = kasan_reset_tag(addr);
 
 	/*
-	 * Skip KFENCE memory if called explicitly outside of sl*b. Also note
-	 * that calls to ksize(), where size is not a multiple of machine-word
-	 * size, would otherwise poison the invalid portion of the word.
+	 * Skip KFENCE memory if called explicitly outside of sl*b.
 	 */
 	if (is_kfence_address(addr))
 		return;
-- 
2.34.1