Re: [PATCH v3] proc_sysctl: fix oops caused by incorrect command parameters.

[Andrew Morton]

On Tue, 12 Jan 2021 11:31:55 +0800 Xiaoming Ni <nixiaoming@xxxxxxxxxx> wrote:

> The process_sysctl_arg() does not check whether val is empty before
>  invoking strlen(val). If the command line parameter () is incorrectly
>  configured and val is empty, oops is triggered.
> 
> --- a/fs/proc/proc_sysctl.c
> +++ b/fs/proc/proc_sysctl.c
> @@ -1770,6 +1770,9 @@ static int process_sysctl_arg(char *param, char *val,
>  			return 0;
>  	}
>  
> +	if (!val)
> +		return -EINVAL;
> +

I think v2 (return 0) was preferable.  Because all the other error-out
cases in process_sysctl_arg() also do a `return 0'.

If we're going to do a separate "patch: make process_sysctl_arg()
return an errno instead of 0" then fine, we can discuss that.  But it's
conceptually a different work from fixing this situation.