Re: [PATCH v4 1/4] lib/ucs2_string: Add UCS-2 strlcpy function

[Kees Cook]

On Mon, May 29, 2023 at 01:03:48AM +0200, Maximilian Luz wrote:
> Add a ucs2_strlcpy() function for UCS-2 strings. The behavior is
> equivalent to the standard strlcpy() function, just for 16-bit character
> UCS-2 strings.

Eek, no. strlcpy() is dangerous in multiple ways[1]. Please implement
strscpy() (i.e. use strnlen(), negative error on truncation, etc).
Additionally, it'd be nice of the ucs2 helpers here also implemented the
rest of the CONFIG_FORTIFY_SOURCE mitigations (i.e. checking for source
and destination buffer size overflows at compile-time and run-time with
__builtin_object_size() and __builtin_dynamoc_object_size() respectively).

-Kees

[1] https://docs.kernel.org/process/deprecated.html#strlcpy

-- 
Kees Cook