On Thu, Oct 19, 2023 at 05:29:01PM +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 expect priv->firmware_id to be NUL-terminated based on its usage
> with seq_printf() and strlen() in atmel.c:
> 1420 | seq_printf(m, "%s loaded by host\n", priv->firmware_id);
> ...
> 3884 | if (strlen(priv->firmware_id) == 0) {
>
> NUL-padding is not required, which is evident by the usage of a plain
> strcpy():
> 3891 | strcpy(priv->firmware_id, "atmel_at76c502.bin");
>
> 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.
>
> Let's also replace hard-coded lengths to be `sizeof(...)` for buffers
> that the compiler can detect the size for as this is less error prone.
>
> Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
> Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strcpy [2]
> Link: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html [3]
> Link: https://github.com/KSPP/linux/issues/90
> Cc: linux-hardening@xxxxxxxxxxxxxxx
> Signed-off-by: Justin Stitt <justinstitt@xxxxxxxxxx>
Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>
--
Kees Cook
