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Commit 7ed2f9e6 authored by Alexander Potapenko's avatar Alexander Potapenko Committed by Linus Torvalds
Browse files

mm, kasan: SLAB support 



Add KASAN hooks to SLAB allocator.

This patch is based on the "mm: kasan: unified support for SLUB and SLAB
allocators" patch originally prepared by Dmitry Chernenkov.

Signed-off-by: default avatarAlexander Potapenko <glider@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Andrey Konovalov <adech.fo@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Konstantin Serebryany <kcc@google.com>
Cc: Dmitry Chernenkov <dmitryc@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent e6e8379c

Documentation/kasan.txt

+2 −3
Original line number Diff line number Diff line
@@ -12,8 +12,7 @@ KASAN uses compile-time instrumentation for checking every memory access, 
therefore you will need a GCC version 4.9.2 or later. GCC 5.0 or later is

required for detection of out-of-bounds accesses to stack or global variables.



Currently KASAN is supported only for x86_64 architecture and requires the

kernel to be built with the SLUB allocator.

Currently KASAN is supported only for x86_64 architecture.



1. Usage

========
@@ -27,7 +26,7 @@ inline are compiler instrumentation types. The former produces smaller binary 
the latter is 1.1 - 2 times faster. Inline instrumentation requires a GCC

version 5.0 or later.



Currently KASAN works only with the SLUB memory allocator.

KASAN works with both SLUB and SLAB memory allocators.

For better bug detection and nicer reporting, enable CONFIG_STACKTRACE.



To disable instrumentation for specific files or directories, add a line

include/linux/kasan.h

+12 −0
Original line number Diff line number Diff line
@@ -48,6 +48,9 @@ void kasan_unpoison_task_stack(struct task_struct *task); 
void kasan_alloc_pages(struct page *page, unsigned int order);

void kasan_free_pages(struct page *page, unsigned int order);



void kasan_cache_create(struct kmem_cache *cache, size_t *size,

			unsigned long *flags);



void kasan_poison_slab(struct page *page);

void kasan_unpoison_object_data(struct kmem_cache *cache, void *object);

void kasan_poison_object_data(struct kmem_cache *cache, void *object);
@@ -61,6 +64,11 @@ void kasan_krealloc(const void *object, size_t new_size); 
void kasan_slab_alloc(struct kmem_cache *s, void *object);

void kasan_slab_free(struct kmem_cache *s, void *object);



struct kasan_cache {

	int alloc_meta_offset;

	int free_meta_offset;

};



int kasan_module_alloc(void *addr, size_t size);

void kasan_free_shadow(const struct vm_struct *vm);
@@ -76,6 +84,10 @@ static inline void kasan_disable_current(void) {} 
static inline void kasan_alloc_pages(struct page *page, unsigned int order) {}

static inline void kasan_free_pages(struct page *page, unsigned int order) {}



static inline void kasan_cache_create(struct kmem_cache *cache,

				      size_t *size,

				      unsigned long *flags) {}



static inline void kasan_poison_slab(struct page *page) {}

static inline void kasan_unpoison_object_data(struct kmem_cache *cache,

					void *object) {}

include/linux/slab.h

+6 −0
Original line number Diff line number Diff line
@@ -92,6 +92,12 @@ 
# define SLAB_ACCOUNT		0x00000000UL

#endif



#ifdef CONFIG_KASAN

#define SLAB_KASAN		0x08000000UL

#else

#define SLAB_KASAN		0x00000000UL

#endif



/* The following flags affect the page allocator grouping pages by mobility */

#define SLAB_RECLAIM_ACCOUNT	0x00020000UL		/* Objects are reclaimable */

#define SLAB_TEMPORARY		SLAB_RECLAIM_ACCOUNT	/* Objects are short-lived */

include/linux/slab_def.h

+14 −0
Original line number Diff line number Diff line
@@ -76,8 +76,22 @@ struct kmem_cache { 
#ifdef CONFIG_MEMCG

	struct memcg_cache_params memcg_params;

#endif

#ifdef CONFIG_KASAN

	struct kasan_cache kasan_info;

#endif



	struct kmem_cache_node *node[MAX_NUMNODES];

};



static inline void *nearest_obj(struct kmem_cache *cache, struct page *page,

				void *x) {

	void *object = x - (x - page->s_mem) % cache->size;

	void *last_object = page->s_mem + (cache->num - 1) * cache->size;



	if (unlikely(object > last_object))

		return last_object;

	else

		return object;

}



#endif	/* _LINUX_SLAB_DEF_H */

include/linux/slub_def.h

+11 −0
Original line number Diff line number Diff line
@@ -130,4 +130,15 @@ static inline void *virt_to_obj(struct kmem_cache *s, 
void object_err(struct kmem_cache *s, struct page *page,

		u8 *object, char *reason);



static inline void *nearest_obj(struct kmem_cache *cache, struct page *page,

				void *x) {

	void *object = x - (x - page_address(page)) % cache->size;

	void *last_object = page_address(page) +

		(page->objects - 1) * cache->size;

	if (unlikely(object > last_object))

		return last_object;

	else

		return object;

}



#endif /* _LINUX_SLUB_DEF_H */