Re: [PATCH v2] qed: replace uses of strncpy

[Kees Cook]

On Thu, Oct 12, 2023 at 06:35:41PM +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.
> 
> This patch eliminates three uses of strncpy():
> 
> Firstly, `dest` is expected to be NUL-terminated which is evident by the
> manual setting of a NUL-byte at size - 1. For this use specifically,
> strscpy() is a viable replacement due to the fact that it guarantees
> NUL-termination on the destination buffer.
> 
> The next two cases should simply be memcpy() as the size of the src
> string is always 3 and the destination string just wants the first 3
> bytes changed.
> 
> To be clear, there are no buffer overread bugs in the current code as
> the sizes and offsets are carefully managed such that buffers are
> NUL-terminated. However, with these changes, the code is now more robust
> and less ambiguous (and hopefully easier to read).
> 
> 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
> Cc: Kees Cook <keescook@xxxxxxxxxxxx>
> Signed-off-by: Justin Stitt <justinstitt@xxxxxxxxxx>

Yup, this looks good to me now. Thanks!

Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>

-- 
Kees Cook