Re: [PATCH] scsi: ibmvscsi: replace deprecated strncpy with strscpy

Kees Cook
2023-11-30T21:13:34Z

On Mon, Oct 30, 2023 at 08:40:48PM +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 partition_name to be NUL-terminated based on its usage with
> format strings:
> | dev_info(hostdata->dev, "host srp version: %s, "
> | "host partition %s (%d), OS %d, max io %u\n",
> | hostdata->madapter_info.srp_version,
> | hostdata->madapter_info.partition_name,
> | be32_to_cpu(hostdata->madapter_info.partition_number),
> | be32_to_cpu(hostdata->madapter_info.os_type),
> | be32_to_cpu(hostdata->madapter_info.port_max_txu[0]));
> ...
> | len = snprintf(buf, PAGE_SIZE, "%s\n",
> | hostdata->madapter_info.partition_name);
>
> Moreover, NUL-padding is not required as madapter_info is explicitly
> memset to 0:
> | memset(&hostdata->madapter_info, 0x00,
> | sizeof(hostdata->madapter_info));
>
> 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.
>
> 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@vger.kernel.org
> Signed-off-by: Justin Stitt <justinstitt@google.com>

Agreed; this conversion looks correct to me too.

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

--
Kees Cook