[RFC PATCH] um: replace deprecated strncpy with strscpy

[Kees Cook]

On Sun, Jun 08, 2025 at 03:00:06AM +0530, Brahmajit Das 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.
> 
> This modification is mainly due to the concerns on
> https://github.com/KSPP/linux/issues/336, where it was mentioned that
> strncpy_from_user is confusingly named as it does not NUL-pad the
> destination, but it does NOT guarantee NUL-termination.
> With this approach/patch we can always ensure that the dst buffer is NUL
> terminated.

I think we need wholesale fix the kernel's usage of
strncpy_from_user()... first, how is it being used? Are things being
manually terminated? Are something destinations not actually C Strings?
We may want two APIs (like strtomem vs strscpy). And then since we're
dealing with user data, I would think padding should be included?

-- 
Kees Cook