Revert "mm/slub: fix a memory leak in sysfs_slab_add()"

This reverts commit dde3c6b72a16c2db826f54b2d49bdea26c3534a2.

syzbot report a double-free bug. The following case can cause this bug.

 - mm/slab_common.c: create_cache(): if the __kmem_cache_create() fails,
   it does:

	out_free_cache:
		kmem_cache_free(kmem_cache, s);

 - but __kmem_cache_create() - at least for slub() - will have done

	sysfs_slab_add(s)
		-> sysfs_create_group() .. fails ..
		-> kobject_del(&s->kobj); .. which frees s ...

We can't remove the kmem_cache_free() in create_cache(), because other
error cases of __kmem_cache_create() do not free this.

So, revert the commit dde3c6b72a16 ("mm/slub: fix a memory leak in
sysfs_slab_add()") to fix this.

Reported-by: syzbot+d0bd96b4696c1ef67991@syzkaller.appspotmail.com
Fixes: dde3c6b72a16 ("mm/slub: fix a memory leak in sysfs_slab_add()")
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Wang Hai <wanghai38@huawei.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/slub.c b/mm/slub.c
index 69742ab..7ecbbbe 100644 (file)
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -5625,10 +5625,8 @@ static int sysfs_slab_add(struct kmem_cache *s)
 
        s->kobj.kset = kset;
        err = kobject_init_and_add(&s->kobj, &slab_ktype, NULL, "%s", name);
-       if (err) {
-               kobject_put(&s->kobj);
+       if (err)
                goto out;
-       }
 
        err = sysfs_create_group(&s->kobj, &slab_attr_group);
        if (err)