On Thu, Oct 12, 2023 at 07:44:29PM +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 fw_info->fw_file_name to be NUL-terminated based on its use
> within _request_firmware_prepare() wherein `name` refers to it:
> | if (firmware_request_builtin_buf(firmware, name, dbuf, size)) {
> | dev_dbg(device, "using built-in %s\n", name);
> | return 0; /* assigned */
> | }
> ... and with firmware_request_builtin() also via `name`:
> | if (strcmp(name, b_fw->name) == 0) {
>
> There is no evidence that NUL-padding is required.
>
> 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.
When doing the hard-coded value to sizeof(), can you include in the
commit log the rationale for it? For example:
Additionally replace size macro (QLC_FW_FILE_NAME_LEN) with
sizeof(fw_info->fw_file_name) to more directly tie the maximum buffer
size to the destination buffer:
struct qlc_83xx_fw_info {
...
char fw_file_name[QLC_FW_FILE_NAME_LEN];
};
>
> 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 <justinst...@google.com>
> ---
> Note: build-tested only.
>
> Found with: $ rg "strncpy\("
> ---
> drivers/net/ethernet/qlogic/qlcnic/qlcnic_83xx_init.c | 12 ++++++------
> 1 file changed, 6 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/net/ethernet/qlogic/qlcnic/qlcnic_83xx_init.c
> b/drivers/net/ethernet/qlogic/qlcnic/qlcnic_83xx_init.c
> index c95d56e56c59..b733374b4dc5 100644
> --- a/drivers/net/ethernet/qlogic/qlcnic/qlcnic_83xx_init.c
> +++ b/drivers/net/ethernet/qlogic/qlcnic/qlcnic_83xx_init.c
> @@ -2092,8 +2092,8 @@ static int qlcnic_83xx_run_post(struct qlcnic_adapter
> *adapter)
> return -EINVAL;
> }
>
> - strncpy(fw_info->fw_file_name, QLC_83XX_POST_FW_FILE_NAME,
> - QLC_FW_FILE_NAME_LEN);
> + strscpy(fw_info->fw_file_name, QLC_83XX_POST_FW_FILE_NAME,
> + sizeof(fw_info->fw_file_name));
>
> ret = request_firmware(&fw_info->fw, fw_info->fw_file_name, dev);
> if (ret) {
> @@ -2396,12 +2396,12 @@ static int qlcnic_83xx_get_fw_info(struct
> qlcnic_adapter *adapter)
> switch (pdev->device) {
> case PCI_DEVICE_ID_QLOGIC_QLE834X:
> case PCI_DEVICE_ID_QLOGIC_QLE8830:
> - strncpy(fw_info->fw_file_name, QLC_83XX_FW_FILE_NAME,
> - QLC_FW_FILE_NAME_LEN);
> + strscpy(fw_info->fw_file_name, QLC_83XX_FW_FILE_NAME,
> + sizeof(fw_info->fw_file_name));
> break;
> case PCI_DEVICE_ID_QLOGIC_QLE844X:
> - strncpy(fw_info->fw_file_name, QLC_84XX_FW_FILE_NAME,
> - QLC_FW_FILE_NAME_LEN);
> + strscpy(fw_info->fw_file_name, QLC_84XX_FW_FILE_NAME,
> + sizeof(fw_info->fw_file_name));
> break;
> default:
> dev_err(&pdev->dev, "%s: Invalid device id\n",
But yes, this all looks right to me.
Reviewed-by: Kees Cook <keesc...@chromium.org>
--
Kees Cook
