* [PATCH] wifi: iwlwifi: fw: replace deprecated strncpy with strscpy
@ 2023-10-17 21:58 Justin Stitt
2023-10-19 1:22 ` Kees Cook
0 siblings, 1 reply; 2+ messages in thread
From: Justin Stitt @ 2023-10-17 21:58 UTC (permalink / raw)
To: Gregory Greenman, Kalle Valo
Cc: linux-wireless, linux-kernel, linux-hardening, Justin Stitt
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.
Neither of these symbols seem to be actually used after being assigned.
Which means our replacement doesn't really matter. At any rate, it would
seem NUL-padding is not required so let's use `strscpy` [2] due to the
fact that it guarantees NUL-termination on the destination buffer
without unnecessarily NUL-padding. (but maybe these should be
used or removed).
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/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..5455f8d1aab0 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(dump_info->dev_human_readable, fwrt->trans->name,
+ sizeof(dump_info->dev_human_readable));
+ strscpy(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>
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] wifi: iwlwifi: fw: replace deprecated strncpy with strscpy
2023-10-17 21:58 [PATCH] wifi: iwlwifi: fw: replace deprecated strncpy with strscpy Justin Stitt
@ 2023-10-19 1:22 ` Kees Cook
0 siblings, 0 replies; 2+ messages in thread
From: Kees Cook @ 2023-10-19 1:22 UTC (permalink / raw)
To: Justin Stitt
Cc: Gregory Greenman, Kalle Valo, linux-wireless, linux-kernel,
linux-hardening
On Tue, Oct 17, 2023 at 09:58:44PM +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.
>
> Neither of these symbols seem to be actually used after being assigned.
> Which means our replacement doesn't really matter. At any rate, it would
> seem NUL-padding is not required so let's use `strscpy` [2] due to the
> fact that it guarantees NUL-termination on the destination buffer
> without unnecessarily NUL-padding. (but maybe these should be
> used or removed).
This appears to be crossing the file boundary. I would be more
comfortable seeing strscpy_pad() used here just to make sure there is no
behavior change at all.
-Kees
>
> 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/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..5455f8d1aab0 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(dump_info->dev_human_readable, fwrt->trans->name,
> + sizeof(dump_info->dev_human_readable));
> + strscpy(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
^ permalink raw reply [flat|nested] 2+ messages in thread
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2023-10-17 21:58 [PATCH] wifi: iwlwifi: fw: replace deprecated strncpy with strscpy Justin Stitt
2023-10-19 1:22 ` Kees Cook
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