sysfs: don't remove existing directory on update failure

In the Linux kernel, the following vulnerability has been resolved: sysfs: don't remove existing directory on update failure When sysfs_update_group() is called for a named group and create_files() fails (e.g. -ENOMEM), internal_create_group() calls kernfs_remove(kn) on the group directory. In the update path, kn was obtained via kernfs_find_and_get() and refers to a directory that already existed before this call. Removing it silently destroys a sysfs group that the caller did not create. Only remove the directory if we created it ourselves. On update failure the directory remains as it is left empty by remove_files() inside create_files(), but can be repopulated by a retry.