[PATCH v2 15/20] 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 at google.com>
Reviewed-by: Dmitry Vyukov <dvyukov at google.com>
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 60793f8695a8..69ab880abacc 100644
--- a/mm/kasan/common.c
+++ b/mm/kasan/common.c
@@ -218,9 +218,7 @@ void __kasan_unpoison_object_data(struct kmem_cache *cache, void *object)
 
 void __kasan_poison_object_data(struct kmem_cache *cache, void *object)
 {
-	kasan_poison_memory(object,
-			round_up(cache->object_size, KASAN_GRANULE_SIZE),
-			KASAN_KMALLOC_REDZONE);
+	kasan_poison_memory(object, cache->object_size, KASAN_KMALLOC_REDZONE);
 }
 
 /*
@@ -293,7 +291,6 @@ 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;
@@ -314,8 +311,7 @@ static bool ____kasan_slab_free(struct kmem_cache *cache, void *object,
 		return true;
 	}
 
-	rounded_up_size = round_up(cache->object_size, KASAN_GRANULE_SIZE);
-	kasan_poison_memory(object, rounded_up_size, KASAN_KMALLOC_FREE);
+	kasan_poison_memory(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 8e4fa9157a0b..3f64c9ecbcc0 100644
--- a/mm/kasan/shadow.c
+++ b/mm/kasan/shadow.c
@@ -82,6 +82,7 @@ void kasan_poison_memory(const void *address, size_t size, u8 value)
 	 * addresses to this function.
 	 */
 	address = kasan_reset_tag(address);
+	size = round_up(size, KASAN_GRANULE_SIZE);
 
 	shadow_start = kasan_mem_to_shadow(address);
 	shadow_end = kasan_mem_to_shadow(address + size);
-- 
2.29.2.222.g5d2a92d10f8-goog