wifi: iwlwifi: fw: replace deprecated strncpy with strscpy_pad

strncpy() is deprecated for use on NUL-terminated destination strings
[1] and as such we should prefer more robust and less ambiguous string
interfaces.

Based on the deliberate `sizeof(dest) ... - 1` pattern we can see that
both dump_info->dev_human_readable and dump_info->bus_human_readable are
intended to be NUL-terminated.

Moreover, since this seems to cross the file boundary let's NUL-pad to
ensure no behavior change.

strscpy_pad() covers both the NUL-termination and NUL-padding, let's use
it.

Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
Link: KSPP#90
Cc: linux-hardening@vger.kernel.org
Signed-off-by: Justin Stitt <justinstitt@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20231019-strncpy-drivers-net-wireless-intel-iwlwifi-fw-dbg-c-v2-1-179b211a374b@google.com

drivers/net/wireless/intel/iwlwifi/fw/dbg.c

@@ -880,10 +880,10 @@ iwl_fw_error_dump_file(struct iwl_fw_runtime *fwrt,
 			cpu_to_le32(fwrt->trans->hw_rev_step);
 		memcpy(dump_info->fw_human_readable, fwrt->fw->human_readable,
 		       sizeof(dump_info->fw_human_readable));
-		strncpy(dump_info->dev_human_readable, fwrt->trans->name,
-			sizeof(dump_info->dev_human_readable) - 1);
-		strncpy(dump_info->bus_human_readable, fwrt->dev->bus->name,
-			sizeof(dump_info->bus_human_readable) - 1);
+		strscpy_pad(dump_info->dev_human_readable, fwrt->trans->name,
+			sizeof(dump_info->dev_human_readable));
+		strscpy_pad(dump_info->bus_human_readable, fwrt->dev->bus->name,
+			sizeof(dump_info->bus_human_readable));
 		dump_info->num_of_lmacs = fwrt->smem_cfg.num_lmacs;
 		dump_info->lmac_err_id[0] =
 			cpu_to_le32(fwrt->dump.lmac_err_id[0]);