[PATCH mm v3 14/19] kasan: don't round_up too much

[Andrey Konovalov]

For hardware tag-based mode kasan_poison_memory() already rounds up the
size. Do the same for software modes and remove round_up() from the common
code.

Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Reviewed-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Reviewed-by: Marco Elver <elver@xxxxxxxxxx>
Link: https://linux-review.googlesource.com/id/Ib397128fac6eba874008662b4964d65352db4aa4
---
 mm/kasan/common.c | 8 ++------
 mm/kasan/shadow.c | 1 +
 2 files changed, 3 insertions(+), 6 deletions(-)

diff --git a/mm/kasan/common.c b/mm/kasan/common.c
index 1205faac90bd..1a88e4005181 100644
--- a/mm/kasan/common.c
+++ b/mm/kasan/common.c
@@ -214,9 +214,7 @@ void __kasan_unpoison_object_data(struct kmem_cache *cache, void *object)
 
 void __kasan_poison_object_data(struct kmem_cache *cache, void *object)
 {
-	poison_range(object,
-			round_up(cache->object_size, KASAN_GRANULE_SIZE),
-			KASAN_KMALLOC_REDZONE);
+	poison_range(object, cache->object_size, KASAN_KMALLOC_REDZONE);
 }
 
 /*
@@ -289,7 +287,6 @@ static bool ____kasan_slab_free(struct kmem_cache *cache, void *object,
 {
 	u8 tag;
 	void *tagged_object;
-	unsigned long rounded_up_size;
 
 	tag = get_tag(object);
 	tagged_object = object;
@@ -313,8 +310,7 @@ static bool ____kasan_slab_free(struct kmem_cache *cache, void *object,
 		return true;
 	}
 
-	rounded_up_size = round_up(cache->object_size, KASAN_GRANULE_SIZE);
-	poison_range(object, rounded_up_size, KASAN_KMALLOC_FREE);
+	poison_range(object, cache->object_size, KASAN_KMALLOC_FREE);
 
 	if (!kasan_stack_collection_enabled())
 		return false;
diff --git a/mm/kasan/shadow.c b/mm/kasan/shadow.c
index 37153bd1c126..e9efe88f7679 100644
--- a/mm/kasan/shadow.c
+++ b/mm/kasan/shadow.c
@@ -83,6 +83,7 @@ void poison_range(const void *address, size_t size, u8 value)
 	 * addresses to this function.
 	 */
 	address = kasan_reset_tag(address);
+	size = round_up(size, KASAN_GRANULE_SIZE);
 
 	/* Skip KFENCE memory if called explicitly outside of sl*b. */
 	if (is_kfence_address(address))
-- 
2.29.2.299.gdc1121823c-goog