Commit 10d1f8cb authored by Marco Elver's avatar Marco Elver Committed by Linus Torvalds
Browse files

mm/slab: refactor common ksize KASAN logic into slab_common.c 

This refactors common code of ksize() between the various allocators into
slab_common.c: __ksize() is the allocator-specific implementation without
instrumentation, whereas ksize() includes the required KASAN logic.

Link: http://lkml.kernel.org/r/20190626142014.141844-5-elver@google.com


Signed-off-by: default avatarMarco Elver <elver@google.com>
Acked-by: default avatarChristoph Lameter <cl@linux.com>
Reviewed-by: default avatarAndrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent bb104ed7

include/linux/slab.h

+1 −0
Original line number Diff line number Diff line
@@ -184,6 +184,7 @@ void * __must_check __krealloc(const void *, size_t, gfp_t); 
void * __must_check krealloc(const void *, size_t, gfp_t);

void kfree(const void *);

void kzfree(const void *);

size_t __ksize(const void *);

size_t ksize(const void *);



#ifdef CONFIG_HAVE_HARDENED_USERCOPY_ALLOCATOR

mm/slab.c

+5 −17
Original line number Diff line number Diff line
@@ -4204,20 +4204,12 @@ void __check_heap_object(const void *ptr, unsigned long n, struct page *page, 
#endif /* CONFIG_HARDENED_USERCOPY */



/**

 * ksize - get the actual amount of memory allocated for a given object

 * @objp: Pointer to the object

 * __ksize -- Uninstrumented ksize.

 *

 * kmalloc may internally round up allocations and return more memory

 * than requested. ksize() can be used to determine the actual amount of

 * memory allocated. The caller may use this additional memory, even though

 * a smaller amount of memory was initially specified with the kmalloc call.

 * The caller must guarantee that objp points to a valid object previously

 * allocated with either kmalloc() or kmem_cache_alloc(). The object

 * must not be freed during the duration of the call.

 *

 * Return: size of the actual memory used by @objp in bytes

 * Unlike ksize(), __ksize() is uninstrumented, and does not provide the same

 * safety checks as ksize() with KASAN instrumentation enabled.

 */

size_t ksize(const void *objp)

size_t __ksize(const void *objp)

{

	struct kmem_cache *c;

	size_t size;
@@ -4228,11 +4220,7 @@ size_t ksize(const void *objp) 


	c = virt_to_cache(objp);

	size = c ? c->object_size : 0;

	/* We assume that ksize callers could use the whole allocated area,

	 * so we need to unpoison this area.

	 */

	kasan_unpoison_shadow(objp, size);



	return size;

}

EXPORT_SYMBOL(ksize);
 
EXPORT_SYMBOL(__ksize);

mm/slab_common.c

+26 −0
Original line number Diff line number Diff line
@@ -1597,6 +1597,32 @@ void kzfree(const void *p) 
}

EXPORT_SYMBOL(kzfree);



/**

 * ksize - get the actual amount of memory allocated for a given object

 * @objp: Pointer to the object

 *

 * kmalloc may internally round up allocations and return more memory

 * than requested. ksize() can be used to determine the actual amount of

 * memory allocated. The caller may use this additional memory, even though

 * a smaller amount of memory was initially specified with the kmalloc call.

 * The caller must guarantee that objp points to a valid object previously

 * allocated with either kmalloc() or kmem_cache_alloc(). The object

 * must not be freed during the duration of the call.

 *

 * Return: size of the actual memory used by @objp in bytes

 */

size_t ksize(const void *objp)

{

	size_t size = __ksize(objp);

	/*

	 * We assume that ksize callers could use whole allocated area,

	 * so we need to unpoison this area.

	 */

	kasan_unpoison_shadow(objp, size);

	return size;

}

EXPORT_SYMBOL(ksize);



/* Tracepoints definitions. */

EXPORT_TRACEPOINT_SYMBOL(kmalloc);

EXPORT_TRACEPOINT_SYMBOL(kmem_cache_alloc);

mm/slob.c

+2 −2
Original line number Diff line number Diff line
@@ -527,7 +527,7 @@ void kfree(const void *block) 
EXPORT_SYMBOL(kfree);



/* can't use ksize for kmem_cache_alloc memory, only kmalloc */

size_t ksize(const void *block)

size_t __ksize(const void *block)

{

	struct page *sp;

	int align;
@@ -545,7 +545,7 @@ size_t ksize(const void *block) 
	m = (unsigned int *)(block - align);

	return SLOB_UNITS(*m) * SLOB_UNIT;

}

EXPORT_SYMBOL(ksize);

EXPORT_SYMBOL(__ksize);



int __kmem_cache_create(struct kmem_cache *c, slab_flags_t flags)

{

mm/slub.c

+2 −12
Original line number Diff line number Diff line
@@ -3895,7 +3895,7 @@ void __check_heap_object(const void *ptr, unsigned long n, struct page *page, 
}

#endif /* CONFIG_HARDENED_USERCOPY */



static size_t __ksize(const void *object)

size_t __ksize(const void *object)

{

	struct page *page;
@@ -3911,17 +3911,7 @@ static size_t __ksize(const void *object) 


	return slab_ksize(page->slab_cache);

}



size_t ksize(const void *object)

{

	size_t size = __ksize(object);

	/* We assume that ksize callers could use whole allocated area,

	 * so we need to unpoison this area.

	 */

	kasan_unpoison_shadow(object, size);

	return size;

}

EXPORT_SYMBOL(ksize);

EXPORT_SYMBOL(__ksize);



void kfree(const void *x)

{

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