Re: [syzbot] WARNING in internal_create_group

[Christoph Hellwig]

On Thu, Aug 12, 2021 at 12:37:08AM +0300, Pavel Skripkin wrote:
> --- a/drivers/block/nbd.c
> +++ b/drivers/block/nbd.c
> @@ -1725,7 +1725,17 @@ static int nbd_dev_add(int index)
>  	refcount_set(&nbd->refs, 1);
>  	INIT_LIST_HEAD(&nbd->list);
>  	disk->major = NBD_MAJOR;
> +
> +	/* Too big first_minor can cause duplicate creation of
> +	 * sysfs files/links, since first_minor will be truncated to
> +	 * byte in __device_add_disk().
> +	 */
>  	disk->first_minor = index << part_shift;
> +	if (disk->first_minor > 0xff) {
> +		err = -EINVAL;
> +		goto out_free_idr;
> +	}
> +
>  	disk->minors = 1 << part_shift;
>  	disk->fops = &nbd_fops;
>  	disk->private_data = nbd;
>
>
> What to do you think about it?

This sounds reasonable and looks good to me.