Re: [PATCH v2] ASoC: Intel: Skylake: replace deprecated strncpy with strscpy

[Kees Cook <keescook@chromium.org>]

On Thu, Jul 27, 2023 at 08:30:18PM +0000, Justin Stitt wrote:
> `strncpy` is deprecated for use on NUL-terminated destination strings [1].
> 
> A suitable replacement is `strscpy` [2] due to the fact that it
> guarantees NUL-termination on its destination buffer argument which is
> _not_ the case for `strncpy`!
> 
> It was pretty difficult, in this case, to try and figure out whether or
> not the destination buffer was zero-initialized. If it is and this
> behavior is relied on then perhaps `strscpy_pad` is the preferred
> option here.
> 
> Kees was able to help me out and identify the following code snippet
> which seems to show that the destination buffer is zero-initialized.
> 
> |       skl = devm_kzalloc(&pci->dev, sizeof(*skl), GFP_KERNEL);
> 
> With this information, I opted for `strscpy` since padding is seemingly
> not required.
> 
> [1]: www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings
> [2]: manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html
> 
> Link: https://github.com/KSPP/linux/issues/90
> Suggested-by: Kees Cook <keescook@chromium.org>
> Signed-off-by: Justin Stitt <justinstitt@google.com>

Thanks for the updates! And based on the details from Amadeusz, it
looks safe.

Reviewed-by: Kees Cook <keescook@chromium.org>

-- 
Kees Cook