On Fri, May 31, 2024 at 12:14:56PM -0700, Kees Cook wrote:
...
> diff --git a/mm/slab_common.c b/mm/slab_common.c
> index b5c879fa66bc..f42a98d368a9 100644
> --- a/mm/slab_common.c
> +++ b/mm/slab_common.c
> @@ -392,6 +392,82 @@ kmem_cache_create(const char *name, unsigned int size,
> unsigned int align,
> }
> EXPORT_SYMBOL(kmem_cache_create);
>
> +static struct kmem_cache *kmem_buckets_cache __ro_after_init;
> +
> +kmem_buckets *kmem_buckets_create(const char *name, unsigned int align,
> + slab_flags_t flags,
> + unsigned int useroffset,
> + unsigned int usersize,
> + void (*ctor)(void *))
> +{
> + kmem_buckets *b;
> + int idx;
> +
> + /*
> + * When the separate buckets API is not built in, just return
> + * a non-NULL value for the kmem_buckets pointer, which will be
> + * unused when performing allocations.
> + */
> + if (!IS_ENABLED(CONFIG_SLAB_BUCKETS))
> + return ZERO_SIZE_PTR;
> +
> + if (WARN_ON(!kmem_buckets_cache))
> + return NULL;
> +
> + b = kmem_cache_alloc(kmem_buckets_cache, GFP_KERNEL|__GFP_ZERO);
> + if (WARN_ON(!b))
> + return NULL;
> +
> + flags |= SLAB_NO_MERGE;
> +
> + for (idx = 0; idx < ARRAY_SIZE(kmalloc_caches[KMALLOC_NORMAL]); idx++) {
> + char *short_size, *cache_name;
> + unsigned int cache_useroffset, cache_usersize;
> + unsigned int size;
> +
> + if (!kmalloc_caches[KMALLOC_NORMAL][idx])
> + continue;
> +
> + size = kmalloc_caches[KMALLOC_NORMAL][idx]->object_size;
> + if (!size)
> + continue;
> +
> + short_size = strchr(kmalloc_caches[KMALLOC_NORMAL][idx]->name,
> '-');
> + if (WARN_ON(!short_size))
> + goto fail;
> +
> + cache_name = kasprintf(GFP_KERNEL, "%s-%s", name, short_size +
> 1);
> + if (WARN_ON(!cache_name))
> + goto fail;
> +
> + if (useroffset >= size) {
> + cache_useroffset = 0;
> + cache_usersize = 0;
> + } else {
> + cache_useroffset = useroffset;
> + cache_usersize = min(size - cache_useroffset, usersize);
> + }
> + (*b)[idx] = kmem_cache_create_usercopy(cache_name, size,
> + align, flags, cache_useroffset,
> + cache_usersize, ctor);
> + kfree(cache_name);
> + if (WARN_ON(!(*b)[idx]))
> + goto fail;
> + }
> +
> + return b;
> +
> +fail:
> + for (idx = 0; idx < ARRAY_SIZE(kmalloc_caches[KMALLOC_NORMAL]); idx++) {
> + if ((*b)[idx])
> + kmem_cache_destroy((*b)[idx]);
nit: I don't think it is necessary to guard this with a check for NULL.
> + }
> + kfree(b);
> +
> + return NULL;
> +}
> +EXPORT_SYMBOL(kmem_buckets_create);
