void kfree(const void *objp);
void kfree_sensitive(const void *objp);
size_t __ksize(const void *objp);
+
+/**
+ * ksize - Report actual allocation size of associated object
+ *
+ * @objp: Pointer returned from a prior kmalloc()-family allocation.
+ *
+ * This should not be used for writing beyond the originally requested
+ * allocation size. Either use krealloc() or round up the allocation size
+ * with kmalloc_size_roundup() prior to allocation. If this is used to
+ * access beyond the originally requested allocation size, UBSAN_BOUNDS
+ * and/or FORTIFY_SOURCE may trip, since they only know about the
+ * originally allocated size via the __alloc_size attribute.
+ */
size_t ksize(const void *objp);
+
#ifdef CONFIG_PRINTK
bool kmem_valid_obj(void *object);
void kmem_dump_obj(void *object);
extern void kvfree_sensitive(const void *addr, size_t len);
unsigned int kmem_cache_size(struct kmem_cache *s);
+
+/**
+ * kmalloc_size_roundup - Report allocation bucket size for the given size
+ *
+ * @size: Number of bytes to round up from.
+ *
+ * This returns the number of bytes that would be available in a kmalloc()
+ * allocation of @size bytes. For example, a 126 byte request would be
+ * rounded up to the next sized kmalloc bucket, 128 bytes. (This is strictly
+ * for the general-purpose kmalloc()-based allocations, and is not for the
+ * pre-sized kmem_cache_alloc()-based allocations.)
+ *
+ * Use this to kmalloc() the full bucket size ahead of time instead of using
+ * ksize() to query the size after an allocation.
+ */
+size_t kmalloc_size_roundup(size_t size);
+
void __init kmem_cache_init_late(void);
#if defined(CONFIG_SMP) && defined(CONFIG_SLAB)
#endif /* CONFIG_HARDENED_USERCOPY */
/**
- * __ksize -- Uninstrumented ksize.
+ * __ksize -- Report full size of underlying allocation
* @objp: pointer to the object
*
- * Unlike ksize(), __ksize() is uninstrumented, and does not provide the same
- * safety checks as ksize() with KASAN instrumentation enabled.
+ * This should only be used internally to query the true size of allocations.
+ * It is not meant to be a way to discover the usable size of an allocation
+ * after the fact. Instead, use kmalloc_size_roundup(). Using memory beyond
+ * the originally requested allocation size may trigger KASAN, UBSAN_BOUNDS,
+ * and/or FORTIFY_SOURCE.
*
* Return: size of the actual memory used by @objp in bytes
*/
return kmalloc_caches[kmalloc_type(flags)][index];
}
+size_t kmalloc_size_roundup(size_t size)
+{
+ struct kmem_cache *c;
+
+ /* Short-circuit the 0 size case. */
+ if (unlikely(size == 0))
+ return 0;
+ /* Short-circuit saturated "too-large" case. */
+ if (unlikely(size == SIZE_MAX))
+ return SIZE_MAX;
+ /* Above the smaller buckets, size is a multiple of page size. */
+ if (size > KMALLOC_MAX_CACHE_SIZE)
+ return PAGE_SIZE << get_order(size);
+
+ /* The flags don't matter since size_index is common to all. */
+ c = kmalloc_slab(size, GFP_KERNEL);
+ return c ? c->object_size : 0;
+}
+EXPORT_SYMBOL(kmalloc_size_roundup);
+
#ifdef CONFIG_ZONE_DMA
#define KMALLOC_DMA_NAME(sz) .name[KMALLOC_DMA] = "dma-kmalloc-" #sz,
#else
}
EXPORT_SYMBOL(kfree);
+size_t kmalloc_size_roundup(size_t size)
+{
+ /* Short-circuit the 0 size case. */
+ if (unlikely(size == 0))
+ return 0;
+ /* Short-circuit saturated "too-large" case. */
+ if (unlikely(size == SIZE_MAX))
+ return SIZE_MAX;
+
+ return ALIGN(size, ARCH_KMALLOC_MINALIGN);
+}
+
+EXPORT_SYMBOL(kmalloc_size_roundup);
+
/* can't use ksize for kmem_cache_alloc memory, only kmalloc */
size_t __ksize(const void *block)
{