Re: [PATCH v4 3/9] vsprintf: Do not check address of well-known strings

[Rasmus Villemoes]

On 2018-04-04 10:58, Petr Mladek wrote:
> We are going to check the address using probe_kernel_address(). It will
> be more expensive and it does not make sense for well known address.
> 
> This patch splits the string() function. The variant without the check
> is then used on locations that handle string constants or strings defined
> as local variables.
> 
> This patch does not change the existing behavior.

Please leave string() alone, except for moving the < PAGE_SIZE check to
a new helper checked_string (feel free to find a better name), and use
checked_string for handling %s and possibly the few other cases where
we're passing a user-supplied pointer. That avoids cluttering the entire
file with double-underscore calls, and e.g. in the %pO case, it's easier
to understand why one uses two different *string() helpers if the name
of one somehow conveys how it is different from the other.

Rasmus