qlcnic: replace deprecated strncpy with strscpy

  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.

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(-)


---
base-commit: cbf3a2cb156a2c911d8f38d8247814b4c07f49a2
change-id: 20231012-strncpy-drivers-net-ethernet-qlogic-qlcnic-qlcnic_83xx_init-c-7858019dc583

Best regards,
--
Justin Stitt <justinstitt@google.com>
  

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 <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 <keescook@chromium.org>
  

On Sat, Oct 14, 2023 at 7:47 PM Kees Cook <keescook@chromium.org> wrote:
>
> 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];
>   };
>

Sure, I'll be doing this from now on to make the change more clear!

>
> >
> > 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 <keescook@chromium.org>
>
> --
> Kees Cook

Thanks
Justin
  

On Thu, 12 Oct 2023 19:44:29 +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) {
> 
> [...]

Applied to for-next/hardening, thanks!

[1/1] qlcnic: replace deprecated strncpy with strscpy
      https://git.kernel.org/kees/c/f8bef1ef8095

Take care,
  

On Thu, 30 Nov 2023 14:00:28 -0800 Kees Cook wrote:
> [1/1] qlcnic: replace deprecated strncpy with strscpy
>       https://git.kernel.org/kees/c/f8bef1ef8095

You asked for changes yourself here, please drop all the networking
patches you applied today :|
  

On Thu, Nov 30, 2023 at 10:43:12PM -0800, Jakub Kicinski wrote:
> On Thu, 30 Nov 2023 14:00:28 -0800 Kees Cook wrote:
> > [1/1] qlcnic: replace deprecated strncpy with strscpy
> >       https://git.kernel.org/kees/c/f8bef1ef8095
> 
> You asked for changes yourself here, please drop all the networking
> patches you applied today :|

It was a request for future commit logs. But yes, dropped. Justin, can
you refresh this patch as well, and include the comments about the
sizeof() replacement being safe?