[Devel] [PATCH rh7 20/39] mm/kasan: get rid of ->alloc_size in struct kasan_alloc_meta

[Andrey Ryabinin]

Size of slab object already stored in cache->object_size.

Note, that kmalloc() internally rounds up size of allocation, so
object_size may be not equal to alloc_size, but, usually we don't need
to know the exact size of allocated object.  In case if we need that
information, we still can figure it out from the report.  The dump of
shadow memory allows to identify the end of allocated memory, and
thereby the exact allocation size.

Link: http://lkml.kernel.org/r/1470062715-14077-4-git-send-email-aryabinin@virtuozzo.com
Signed-off-by: Andrey Ryabinin <aryabinin at virtuozzo.com>
Cc: Alexander Potapenko <glider at google.com>
Cc: Dmitry Vyukov <dvyukov at google.com>
Signed-off-by: Andrew Morton <akpm at linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>

https://jira.sw.ru/browse/PSBM-69081
(cherry picked from commit 47b5c2a0f021e90a79845d1a1353780e5edd0bce)
Signed-off-by: Andrey Ryabinin <aryabinin at virtuozzo.com>
---
 mm/kasan/kasan.c  | 1 -
 mm/kasan/kasan.h  | 4 +---
 mm/kasan/report.c | 8 +++-----
 3 files changed, 4 insertions(+), 9 deletions(-)

diff --git a/mm/kasan/kasan.c b/mm/kasan/kasan.c
index d7c814309c3e..a8d3e087dad3 100644
--- a/mm/kasan/kasan.c
+++ b/mm/kasan/kasan.c
@@ -545,7 +545,6 @@ void kasan_kmalloc(struct kmem_cache *cache, const void *object, size_t size,
 			get_alloc_info(cache, object);
 
 		alloc_info->state = KASAN_STATE_ALLOC;
-		alloc_info->alloc_size = size;
 		set_track(&alloc_info->track, flags);
 	}
 }
diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
index 1143e64b6a34..1175fa05f8a6 100644
--- a/mm/kasan/kasan.h
+++ b/mm/kasan/kasan.h
@@ -76,9 +76,7 @@ struct kasan_track {
 
 struct kasan_alloc_meta {
 	struct kasan_track track;
-	u32 state : 2;	/* enum kasan_state */
-	u32 alloc_size : 30;
-	u32 reserved;
+	u32 state;
 };
 
 struct qlist_node {
diff --git a/mm/kasan/report.c b/mm/kasan/report.c
index ef85919f4326..45f17623677e 100644
--- a/mm/kasan/report.c
+++ b/mm/kasan/report.c
@@ -118,7 +118,9 @@ static void kasan_object_err(struct kmem_cache *cache, struct page *page,
 	struct kasan_free_meta *free_info;
 
 	dump_stack();
-	pr_err("Object at %p, in cache %s\n", object, cache->name);
+	pr_err("Object at %p, in cache %s size: %d\n", object, cache->name,
+		cache->object_size);
+
 	if (!(cache->flags & SLAB_KASAN))
 		return;
 	switch (alloc_info->state) {
@@ -126,15 +128,11 @@ static void kasan_object_err(struct kmem_cache *cache, struct page *page,
 		pr_err("Object not allocated yet\n");
 		break;
 	case KASAN_STATE_ALLOC:
-		pr_err("Object allocated with size %u bytes.\n",
-		       alloc_info->alloc_size);
 		pr_err("Allocation:\n");
 		print_track(&alloc_info->track);
 		break;
 	case KASAN_STATE_FREE:
 	case KASAN_STATE_QUARANTINE:
-		pr_err("Object freed, allocated with size %u bytes\n",
-		       alloc_info->alloc_size);
 		free_info = get_free_info(cache, object);
 		pr_err("Allocation:\n");
 		print_track(&alloc_info->track);
-- 
2.13.5