Re: [PATCH] drivers/base/core: refcount kobject and bus on device attribute read / store

[Greg KH]

On Tue, Jun 22, 2021 at 02:06:59PM -0700, Luis Chamberlain wrote:
>  static ssize_t dev_attr_show(struct kobject *kobj, struct attribute *attr,
>  			     char *buf)
>  {
> -	struct device_attribute *dev_attr = to_dev_attr(attr);
> -	struct device *dev = kobj_to_dev(kobj);
> +	struct device_attribute *dev_attr;
> +	struct device *dev;
> +	struct bus_type *bus = NULL;
>  	ssize_t ret = -EIO;
>  
> +	dev = get_device(kobj_to_dev(kobj));
> +	if (!dev)
> +		return ret;

That check is impossible to ever hit, please recognize what things like
kobj_to_dev() really are doing when calling it.

thanks,

greg k-h