Re: [PATCH] qlcnic: replace deprecated strncpy with strscpy
From: Kees Cook <hidden>
Date: 2023-10-15 02:47:22
Also in:
linux-hardening, lkml
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];
};
quoted hunk ↗ jump to hunk
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> --- 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 <redacted> -- Kees Cook