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kasan: introduce kasan_requires_meta

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Add a kasan_requires_meta() helper that indicates whether the enabled
KASAN mode requires per-object metadata and use this helper in the common
code.

Also hide kasan_init_object_meta() under CONFIG_KASAN_GENERIC ifdef check,
as Generic is the only mode that uses per-object metadata.

To allow for a potential future change that makes Generic KASAN support
the kasan.stacktrace command-line parameter, let kasan_requires_meta()
return kasan_stack_collection_enabled() instead of simply returning true.

Link: https://lkml.kernel.org/r/cf837e9996246aaaeebf704ccf8ec26a34fcf64f.1662411799.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Marco Elver <elver@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Peter Collingbourne <pcc@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Andrey Konovalov 2022-09-05 23:05:26 +02:00 committed by Andrew Morton
parent 2f35680172
commit 284f8590a1
3 changed files with 34 additions and 16 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

13
mm/kasan/common.c
View File

@ -88,13 +88,10 @@ asmlinkage void kasan_unpoison_task_stack_below(const void *watermark)
}
#endif /* CONFIG_KASAN_STACK */
/*
* Only allow cache merging when stack collection is disabled and no metadata
* is present.
*/
/* Only allow cache merging when no per-object metadata is present. */
slab_flags_t __kasan_never_merge(void)
{
if (kasan_stack_collection_enabled())
if (kasan_requires_meta())
return SLAB_KASAN;
return 0;
}
@ -152,7 +149,7 @@ void __kasan_cache_create(struct kmem_cache *cache, unsigned int *size,
*/
*flags |= SLAB_KASAN;
if (!kasan_stack_collection_enabled())
if (!kasan_requires_meta())
return;
ok_size = *size;
@ -220,7 +217,7 @@ void __kasan_cache_create_kmalloc(struct kmem_cache *cache)
size_t __kasan_metadata_size(struct kmem_cache *cache)
{
if (!kasan_stack_collection_enabled())
if (!kasan_requires_meta())
return 0;
return (cache->kasan_info.alloc_meta_offset ?
sizeof(struct kasan_alloc_meta) : 0) +
@ -295,7 +292,7 @@ void * __must_check __kasan_init_slab_obj(struct kmem_cache *cache,
const void *object)
{
/* Initialize per-object metadata if it is present. */
if (kasan_stack_collection_enabled())
if (kasan_requires_meta())
kasan_init_object_meta(cache, object);
/* Tag is ignored in set_tag() without CONFIG_KASAN_SW/HW_TAGS */

33
mm/kasan/kasan.h
View File

@ -43,7 +43,7 @@ static inline bool kasan_sync_fault_possible(void)
return kasan_mode == KASAN_MODE_SYNC || kasan_mode == KASAN_MODE_ASYMM;
}
#else
#else /* CONFIG_KASAN_HW_TAGS */
static inline bool kasan_stack_collection_enabled(void)
{
@ -60,7 +60,31 @@ static inline bool kasan_sync_fault_possible(void)
return true;
}
#endif
#endif /* CONFIG_KASAN_HW_TAGS */
#ifdef CONFIG_KASAN_GENERIC
/* Generic KASAN uses per-object metadata to store stack traces. */
static inline bool kasan_requires_meta(void)
{
/*
* Technically, Generic KASAN always collects stack traces right now.
* However, let's use kasan_stack_collection_enabled() in case the
* kasan.stacktrace command-line argument is changed to affect
* Generic KASAN.
*/
return kasan_stack_collection_enabled();
}
#else /* CONFIG_KASAN_GENERIC */
/* Tag-based KASAN modes do not use per-object metadata. */
static inline bool kasan_requires_meta(void)
{
return false;
}
#endif /* CONFIG_KASAN_GENERIC */
#if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
#define KASAN_GRANULE_SIZE (1UL << KASAN_SHADOW_SCALE_SHIFT)
@ -272,13 +296,14 @@ void kasan_report_invalid_free(void *object, unsigned long ip, enum kasan_report
struct page *kasan_addr_to_page(const void *addr);
struct slab *kasan_addr_to_slab(const void *addr);
void kasan_init_object_meta(struct kmem_cache *cache, const void *object);
#ifdef CONFIG_KASAN_GENERIC
void kasan_init_object_meta(struct kmem_cache *cache, const void *object);
struct kasan_alloc_meta *kasan_get_alloc_meta(struct kmem_cache *cache,
const void *object);
struct kasan_free_meta *kasan_get_free_meta(struct kmem_cache *cache,
const void *object);
#else
static inline void kasan_init_object_meta(struct kmem_cache *cache, const void *object) { }
#endif
depot_stack_handle_t kasan_save_stack(gfp_t flags, bool can_alloc);

4
mm/kasan/tags.c
View File

@ -17,10 +17,6 @@
#include "kasan.h"
void kasan_init_object_meta(struct kmem_cache *cache, const void *object)
{
}
void kasan_save_alloc_info(struct kmem_cache *cache, void *object, gfp_t flags)
{
}