mm/slub: fix slab double-free in case of duplicate sysfs filename

sysfs_slab_add() shouldn't call kobject_put at error path: this puts last
reference of kmem-cache kobject and frees it.  Kmem cache will be freed
second time at error path in kmem_cache_create().

For example this happens when slub debug was enabled in runtime and
somebody creates new kmem cache:

# echo 1 | tee /sys/kernel/slab/*/sanity_checks
# modprobe configfs

"configfs_dir_cache" cannot be merged because existing slab have debug and
cannot create new slab because unique name ":t-0000096" already taken.

Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/slub.c b/mm/slub.c
index 3efcdc02082c6b6da37aee479391022542234177..7e9e508263fb2356720fde4c81b1522975314d8f 100644 (file)
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -5283,7 +5283,7 @@ static int sysfs_slab_add(struct kmem_cache *s)
        s->kobj.kset = cache_kset(s);
        err = kobject_init_and_add(&s->kobj, &slab_ktype, NULL, "%s", name);
        if (err)
-               goto out_put_kobj;
+               goto out;
 
        err = sysfs_create_group(&s->kobj, &slab_attr_group);
        if (err)
@@ -5310,8 +5310,6 @@ out:
        return err;
 out_del_kobj:
        kobject_del(&s->kobj);
-out_put_kobj:
-       kobject_put(&s->kobj);
        goto out;
 }