mm: SLUB hardened usercopy support

config SLUB

	bool "SLUB (Unqueued Allocator)"

	select HAVE_HARDENED_USERCOPY_ALLOCATOR

	help

	   SLUB is a slab allocator that minimizes cache line usage

	   instead of managing queues of cached objects (SLAB approach).

EXPORT_SYMBOL(__kmalloc_node);

#endif

#ifdef CONFIG_HARDENED_USERCOPY

/*

 * Rejects objects that are incorrectly sized.

 *

 * Returns NULL if check passes, otherwise const char * to name of cache

 * to indicate an error.

 */

const char *__check_heap_object(const void *ptr, unsigned long n,

				struct page *page)

{

	struct kmem_cache *s;

	unsigned long offset;

	size_t object_size;

	/* Find object and usable object size. */

	s = page->slab_cache;

	object_size = slab_ksize(s);

	/* Reject impossible pointers. */

	if (ptr < page_address(page))

		return s->name;

	/* Find offset within object. */

	offset = (ptr - page_address(page)) % s->size;

	/* Adjust for redzone and reject if within the redzone. */

	if (kmem_cache_debug(s) && s->flags & SLAB_RED_ZONE) {

		if (offset < s->red_left_pad)

			return s->name;

		offset -= s->red_left_pad;

	}

	/* Allow address range falling entirely within object size. */

	if (offset <= object_size && n <= object_size - offset)

		return NULL;

	return s->name;

}

#endif /* CONFIG_HARDENED_USERCOPY */

static size_t __ksize(const void *object)

{

	struct page *page;