block: fix NULL pointer dereference in register_disk

[linux.git] / block / genhd.c

diff --git a/block/genhd.c b/block/genhd.c
index 1dd8fd6613b8d20e2292b73d001396efe1a6f718..78b82d26aa9c446d9a1d898a4224f05038fe2c26 100644 (file)
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -655,10 +655,12 @@ static void register_disk(struct device *parent, struct gendisk *disk,
                kobject_uevent(&part_to_dev(part)->kobj, KOBJ_ADD);
        disk_part_iter_exit(&piter);
 
-       err = sysfs_create_link(&ddev->kobj,
-                               &disk->queue->backing_dev_info->dev->kobj,
-                               "bdi");
-       WARN_ON(err);
+       if (disk->queue->backing_dev_info->dev) {
+               err = sysfs_create_link(&ddev->kobj,
+                         &disk->queue->backing_dev_info->dev->kobj,
+                         "bdi");
+               WARN_ON(err);
+       }
 }
 
 /**