Slab extension objects can't be allocated before slab infrastructure is initialized. Some caches, like kmem_cache and kmem_cache_node, are created before slab infrastructure is initialized. Objects from these caches can't have extension objects. Introduce SLAB_NO_OBJ_EXT slab flag to mark these caches and avoid creating extensions for objects allocated from these slabs. Signed-off-by: Suren Baghdasaryan <surenb@xxxxxxxxxx> Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx> --- include/linux/slab.h | 6 ++++++ mm/slub.c | 5 +++-- 2 files changed, 9 insertions(+), 2 deletions(-) diff --git a/include/linux/slab.h b/include/linux/slab.h index b5f5ee8308d0..58794043ab5b 100644 --- a/include/linux/slab.h +++ b/include/linux/slab.h @@ -28,6 +28,12 @@ */ /* DEBUG: Perform (expensive) checks on alloc/free */ #define SLAB_CONSISTENCY_CHECKS ((slab_flags_t __force)0x00000100U) +/* Slab created using create_boot_cache */ +#ifdef CONFIG_SLAB_OBJ_EXT +#define SLAB_NO_OBJ_EXT ((slab_flags_t __force)0x00000200U) +#else +#define SLAB_NO_OBJ_EXT 0 +#endif /* DEBUG: Red zone objs in a cache */ #define SLAB_RED_ZONE ((slab_flags_t __force)0x00000400U) /* DEBUG: Poison objects */ diff --git a/mm/slub.c b/mm/slub.c index ca803b2949fc..5dc7beda6c0d 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -5697,7 +5697,8 @@ void __init kmem_cache_init(void) node_set(node, slab_nodes); create_boot_cache(kmem_cache_node, "kmem_cache_node", - sizeof(struct kmem_cache_node), SLAB_HWCACHE_ALIGN, 0, 0); + sizeof(struct kmem_cache_node), + SLAB_HWCACHE_ALIGN | SLAB_NO_OBJ_EXT, 0, 0); hotplug_memory_notifier(slab_memory_callback, SLAB_CALLBACK_PRI); @@ -5707,7 +5708,7 @@ void __init kmem_cache_init(void) create_boot_cache(kmem_cache, "kmem_cache", offsetof(struct kmem_cache, node) + nr_node_ids * sizeof(struct kmem_cache_node *), - SLAB_HWCACHE_ALIGN, 0, 0); + SLAB_HWCACHE_ALIGN | SLAB_NO_OBJ_EXT, 0, 0); kmem_cache = bootstrap(&boot_kmem_cache); kmem_cache_node = bootstrap(&boot_kmem_cache_node); -- 2.44.0.rc0.258.g7320e95886-goog
