Re: [PATCH] drm/modes: refactor deprecated strncpy

[Kees Cook <keescook@xxxxxxxxxxxx>]

On Thu, Sep 14, 2023 at 06:08:44PM +0000, Justin Stitt wrote:
> `strncpy` is deprecated for use on NUL-terminated destination strings [1].
> 
> We should prefer more robust and less ambiguous string interfaces.
> 
> A suitable replacement is `strscpy` [2] due to the fact that it guarantees
> NUL-termination on the destination buffer and doesn't incur the
> performance loss of unnecessarily NUL-padding.

How did you decide it didn't need %NUL padding?

I suspect it should have it, as I see what looks like full struct copies
happening in places:

        struct drm_mode_modeinfo umode;

	...
                struct drm_property_blob *blob;

                drm_mode_convert_to_umode(&umode, mode);
                blob = drm_property_create_blob(crtc->dev,
                                                sizeof(umode), &umode);

Can you send a v2 using strscpy_pad() instead?

Thanks!

-Kees

-- 
Kees Cook