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: https://github.com/KSPP/linux/issues/90
Cc: linux-hardening@vger.kernel.org
Signed-off-by: Justin Stitt <justinstitt@google.com>
---
Changes in v2:
- prefer strscpy_pad (thanks Kees)
- Link to v1: https://lore.kernel.org/r/20231017-strncpy-drivers-net-wireless-intel-iwlwifi-fw-dbg-c-v1-1-bf69ec7d1b97@google.com
---
Note: build-tested only.

Found with: $ rg "strncpy\("
---
 drivers/net/wireless/intel/iwlwifi/fw/dbg.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/net/wireless/intel/iwlwifi/fw/dbg.c b/drivers/net/wireless/intel/iwlwifi/fw/dbg.c
index 3ab6a68f1e9f..7aa282592cdc 100644
--- a/drivers/net/wireless/intel/iwlwifi/fw/dbg.c
+++ b/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]);

---
base-commit: 58720809f52779dc0f08e53e54b014209d13eebb
change-id: 20231017-strncpy-drivers-net-wireless-intel-iwlwifi-fw-dbg-c-1f49f00b8a2e

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

Justin Stitt <justinstitt@google.com> 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.
> 
> 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: https://github.com/KSPP/linux/issues/90
> Cc: linux-hardening@vger.kernel.org
> Signed-off-by: Justin Stitt <justinstitt@google.com>
> Reviewed-by: Kees Cook <keescook@chromium.org>

Patch applied to wireless-next.git, thanks.

70582e26f5d9 wifi: iwlwifi: fw: replace deprecated strncpy with strscpy_pad

-- 
https://patchwork.kernel.org/project/linux-wireless/patch/20231019-strncpy-drivers-net-wireless-intel-iwlwifi-fw-dbg-c-v2-1-179b211a374b@google.com/

https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches

On Thu, Oct 19, 2023 at 05:44:59PM +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.
> 
> 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: https://github.com/KSPP/linux/issues/90
> Cc: linux-hardening@vger.kernel.org
> Signed-off-by: Justin Stitt <justinstitt@google.com>

Thread ping. Can the wireless folks please pick this up?

Thanks!

-Kees

> ---
> Changes in v2:
> - prefer strscpy_pad (thanks Kees)
> - Link to v1: https://lore.kernel.org/r/20231017-strncpy-drivers-net-wireless-intel-iwlwifi-fw-dbg-c-v1-1-bf69ec7d1b97@google.com
> ---
> Note: build-tested only.
> 
> Found with: $ rg "strncpy\("
> ---
>  drivers/net/wireless/intel/iwlwifi/fw/dbg.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/net/wireless/intel/iwlwifi/fw/dbg.c b/drivers/net/wireless/intel/iwlwifi/fw/dbg.c
> index 3ab6a68f1e9f..7aa282592cdc 100644
> --- a/drivers/net/wireless/intel/iwlwifi/fw/dbg.c
> +++ b/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]);
> 
> ---
> base-commit: 58720809f52779dc0f08e53e54b014209d13eebb
> change-id: 20231017-strncpy-drivers-net-wireless-intel-iwlwifi-fw-dbg-c-1f49f00b8a2e
> 
> Best regards,
> --
> Justin Stitt <justinstitt@google.com>
> 

-- 
Kees Cook

Kees Cook <keescook@chromium.org> writes:

> On Thu, Oct 19, 2023 at 05:44:59PM +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.
>> 
>> 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: https://github.com/KSPP/linux/issues/90
>> Cc: linux-hardening@vger.kernel.org
>> Signed-off-by: Justin Stitt <justinstitt@google.com>
>
> Thread ping. Can the wireless folks please pick this up?

Yeah, I'll take this directly to wireless-next.

-- 
https://patchwork.kernel.org/project/linux-wireless/list/

https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches

On Thu, Oct 19, 2023 at 05:44:59PM +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.
> 
> 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: https://github.com/KSPP/linux/issues/90
> Cc: linux-hardening@vger.kernel.org
> Signed-off-by: Justin Stitt <justinstitt@google.com>

Thanks for the respin!

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

-- 
Kees Cook