On Wed, Mar 20, 2024 at 10:48:50PM +0000, Justin Stitt wrote:
> strncpy() is deprecated for use on NUL-terminated destination strings
> [1] and as such we should prefer more robust and less ambiguous string
> interfaces.
>
> A better alternative is strscpy() as it guarantees NUL-termination on
> the destination buffer.
>
> Since we are eventually copying over to userspace, let's ensure we
> NUL-pad the destination buffer by using the pad variant of strscpy.
> - core/fb_chrdev.c:
> 234 | err = copy_to_user(&fix32->id, &fix->id, sizeof(fix32->id));
>
> Furthermore, we can use the new 2-argument variants of strscpy() and
> strscpy_pad() introduced by Commit e6584c3964f2f ("string: Allow
> 2-argument strscpy()") to simplify the syntax even more.
>
> Link:
> https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings
> [1]
> Link: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html
> [2]
> Link: https://github.com/KSPP/linux/issues/90
> Cc: linux-harden...@vger.kernel.org
> Signed-off-by: Justin Stitt <justinst...@google.com>
Reviewed-by: Kees Cook <keesc...@chromium.org>
--
Kees Cook
