[PATCH 15/20] kasan: don't round_up too much

From: Andrey Konovalov
Date: Wed Nov 04 2020 - 19:03:15 EST


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>
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);
--
2.29.1.341.ge80a0c044ae-goog