# Re: backlight\_register\_device can oops if name is null ?

- From: devendra.aaru \<hidden\>
- Date: 2013-01-03 05:22:41 
- List: linux-fbdev
- Page: https://ratatoskr.run/linux-fbdev/2013/01/13464524
- Thread: https://ratatoskr.run/linux-fbdev/2012/12/13464471/t.md

```text
>>>
>> so if i understand the code pr_debug code, i see a printk macro assignment,
>>
>> is it something like printk or a wrapper macro around printk are
>> making sure that the strings are non null ?
>
> Sorry, I don't know how printk deals this null.
>
> But I tested null by using ams369fg06 driver as below:
>
> -       bd = backlight_device_register("ams369fg06-bl", &spi->dev, lcd,
> +       bd = backlight_device_register(NULL, &spi->dev, lcd,
>
> Also, I replaced pr_debug with printk as below:
>
> -       pr_debug("backlight_device_register: name=%s\n", name);
> +       printk("backlight_device_register: name=%s\n", name);
>
> In this case, printk message is as below:
>
> backlight_device_register: name=(null)
>
>>

wow, you tested the code, i would have done it with a single module,
great and thanks for lot of information you are putting .

>> the documentation of the backlight_device_register says that "name
>> must be same as the name of the respected frame buffer device", but do
>> we really add a check for the null to do dev_set_name? or fail the
>> registering ?
>
> "name must be same as the name of the respected frame buffer device" is
> not correct. Most backlight drivers are using their driver name as 'name'.
>
> Anyway, in my opinion, deference to null does not seem to happen.
> Now, backlight_device_register() calls are using 'name' properly.
>
>
> However, if a check for the null is added, it will be added to
> backlight_device_register() as below:
>
>
> @@ -292,6 +292,11 @@ struct backlight_device *backlight_device_register(const char *name,
>         struct backlight_device *new_bd;
>         int rc;
>
> +       if (name = NULL) {
> +               pr_err(".....");
> +               return -EINVAL
> +       }
> +

This is what exactly i was thinking, thanks for making a patch too.

If you want to submit it then please take my

Acked-By: Devendra Naga <redacted>
```