From: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Right now, kasan_cache_create() assigns SLAB_KASAN for all KASAN modes
and then sets up metadata-related cache parameters for the Generic mode.
SLAB_KASAN is used in two places:
1. In slab_ksize() to account for per-object metadata when
calculating the size of the accessible memory within the object.
2. In slab_common.c via kasan_never_merge() to prevent merging of
caches with per-object metadata.
Both cases are only relevant when per-object metadata is present, which
is only the case with the Generic mode.
Thus, assign SLAB_KASAN and define kasan_cache_create() only for the
Generic mode.
Also update the SLAB_KASAN-related comment.
Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
---
include/linux/kasan.h | 18 ++++++------------
include/linux/slab.h | 2 +-
mm/kasan/common.c | 16 ----------------
mm/kasan/generic.c | 17 ++++++++++++++++-
4 files changed, 23 insertions(+), 30 deletions(-)
diff --git a/include/linux/kasan.h b/include/linux/kasan.h
index a212c2e3f32d..d811b3d7d2a1 100644
--- a/include/linux/kasan.h
+++ b/include/linux/kasan.h
@@ -128,15 +128,6 @@ static __always_inline void kasan_unpoison_pages(struct page *page,
__kasan_unpoison_pages(page, order, init);
}
-void __kasan_cache_create(struct kmem_cache *cache, unsigned int *size,
- slab_flags_t *flags);
-static __always_inline void kasan_cache_create(struct kmem_cache *cache,
- unsigned int *size, slab_flags_t *flags)
-{
- if (kasan_enabled())
- __kasan_cache_create(cache, size, flags);
-}
-
void __kasan_cache_create_kmalloc(struct kmem_cache *cache);
static __always_inline void kasan_cache_create_kmalloc(struct kmem_cache *cache)
{
@@ -260,9 +251,6 @@ static inline void kasan_poison_pages(struct page *page, unsigned int order,
bool init) {}
static inline void kasan_unpoison_pages(struct page *page, unsigned int order,
bool init) {}
-static inline void kasan_cache_create(struct kmem_cache *cache,
- unsigned int *size,
- slab_flags_t *flags) {}
static inline void kasan_cache_create_kmalloc(struct kmem_cache *cache) {}
static inline void kasan_poison_slab(struct slab *slab) {}
static inline void kasan_unpoison_object_data(struct kmem_cache *cache,
@@ -316,6 +304,8 @@ static inline void kasan_unpoison_task_stack(struct task_struct *task) {}
size_t kasan_metadata_size(struct kmem_cache *cache);
slab_flags_t kasan_never_merge(void);
+void kasan_cache_create(struct kmem_cache *cache, unsigned int *size,
+ slab_flags_t *flags);
void kasan_cache_shrink(struct kmem_cache *cache);
void kasan_cache_shutdown(struct kmem_cache *cache);
@@ -334,6 +324,10 @@ static inline slab_flags_t kasan_never_merge(void)
{
return 0;
}
+/* And no cache-related metadata initialization is required. */
+static inline void kasan_cache_create(struct kmem_cache *cache,
+ unsigned int *size,
+ slab_flags_t *flags) {}
static inline void kasan_cache_shrink(struct kmem_cache *cache) {}
static inline void kasan_cache_shutdown(struct kmem_cache *cache) {}
diff --git a/include/linux/slab.h b/include/linux/slab.h
index 0fefdf528e0d..1c6b7362e82b 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -106,7 +106,7 @@
# define SLAB_ACCOUNT 0
#endif
-#ifdef CONFIG_KASAN
+#ifdef CONFIG_KASAN_GENERIC
#define SLAB_KASAN ((slab_flags_t __force)0x08000000U)
#else
#define SLAB_KASAN 0
diff --git a/mm/kasan/common.c b/mm/kasan/common.c
index f8ef40fa31e3..f937b6c9e86a 100644
--- a/mm/kasan/common.c
+++ b/mm/kasan/common.c
@@ -109,22 +109,6 @@ void __kasan_poison_pages(struct page *page, unsigned int order, bool init)
KASAN_PAGE_FREE, init);
}
-void __kasan_cache_create(struct kmem_cache *cache, unsigned int *size,
- slab_flags_t *flags)
-{
- /*
- * SLAB_KASAN is used to mark caches as ones that are sanitized by
- * KASAN. Currently this flag is used in two places:
- * 1. In slab_ksize() when calculating the size of the accessible
- * memory within the object.
- * 2. In slab_common.c to prevent merging of sanitized caches.
- */
- *flags |= SLAB_KASAN;
-
- if (kasan_requires_meta())
- kasan_init_cache_meta(cache, size);
-}
-
void __kasan_cache_create_kmalloc(struct kmem_cache *cache)
{
cache->kasan_info.is_kmalloc = true;
diff --git a/mm/kasan/generic.c b/mm/kasan/generic.c
index 25333bf3c99f..f6bef347de87 100644
--- a/mm/kasan/generic.c
+++ b/mm/kasan/generic.c
@@ -352,11 +352,26 @@ static inline unsigned int optimal_redzone(unsigned int object_size)
object_size <= (1 << 16) - 1024 ? 1024 : 2048;
}
-void kasan_init_cache_meta(struct kmem_cache *cache, unsigned int *size)
+void kasan_cache_create(struct kmem_cache *cache, unsigned int *size,
+ slab_flags_t *flags)
{
unsigned int ok_size;
unsigned int optimal_size;
+ if (!kasan_requires_meta())
+ return;
+
+ /*
+ * SLAB_KASAN is used to mark caches that are sanitized by KASAN
+ * and that thus have per-object metadata.
+ * Currently this flag is used in two places:
+ * 1. In slab_ksize() to account for per-object metadata when
+ * calculating the size of the accessible memory within the object.
+ * 2. In slab_common.c via kasan_never_merge() to prevent merging of
+ * caches with per-object metadata.
+ */
+ *flags |= SLAB_KASAN;
+
ok_size = *size;
/* Add alloc meta into redzone. */
--
2.25.1
