Re: [PATCH] ACPI: replace deprecated strncpy with strscpy

[Kees Cook]

On Thu, Oct 19, 2023 at 10:47:58PM +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.
> 
> We know dev->name should be NUL-terminated based on the presence of a
> manual NUL-byte assignment.
> 
> NUL-padding is not required as dev is already zero-allocated which
> renders any further NUL-byte assignments redundant:
> dev = pnp_alloc_dev(&pnpacpi_protocol, num, pnpid); --->
>   dev = kzalloc(sizeof(struct pnp_dev), GFP_KERNEL);
> 
> Considering the above, a suitable replacement is `strscpy` [2] due to
> the fact that it guarantees NUL-termination on the destination buffer
> without unnecessarily NUL-padding. This simplifies the code and makes
> the intent/behavior more obvious.
> 
> 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-hardening@xxxxxxxxxxxxxxx
> Signed-off-by: Justin Stitt <justinstitt@xxxxxxxxxx>

Looks clean to me!

Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>

-- 
Kees Cook