Re: [PATCH 02/36] usercopy: Include offset in overflow report

[Christopher Lameter]

On Tue, 9 Jan 2018, Kees Cook wrote:

> -static void report_usercopy(unsigned long len, bool to_user, const char *type)
> +int report_usercopy(const char *name, const char *detail, bool to_user,
> +		    unsigned long offset, unsigned long len)
>  {
> -	pr_emerg("kernel memory %s attempt detected %s '%s' (%lu bytes)\n",
> +	pr_emerg("kernel memory %s attempt detected %s %s%s%s%s (offset %lu, size %lu)\n",
>  		to_user ? "exposure" : "overwrite",
> -		to_user ? "from" : "to", type ? : "unknown", len);
> +		to_user ? "from" : "to",
> +		name ? : "unknown?!",
> +		detail ? " '" : "", detail ? : "", detail ? "'" : "",
> +		offset, len);
>  	/*
>  	 * For greater effect, it would be nice to do do_group_exit(),
>  	 * but BUG() actually hooks all the lock-breaking and per-arch
>  	 * Oops code, so that is used here instead.
>  	 */
>  	BUG();

Should this be a WARN() or so? Or some configuration that changes
BUG() behavior? Otherwise

> +
> +	return -1;

This return code will never be returned.

Why a return code at all? Maybe I will see that in the following patches?