[PATCH] ibmvnic: replace deprecated strncpy with strscpy

[PATCH] ibmvnic: replace deprecated strncpy with strscpy

[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.

NUL-padding is not required as the buffer is already memset to 0:
|       memset(adapter->fw_version, 0, 32);

Note that another usage of strscpy exists on the same buffer:
|       strscpy((char *)adapter->fw_version, "N/A", sizeof(adapter->fw_version));

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.
---
 drivers/net/ethernet/ibm/ibmvnic.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/ibm/ibmvnic.c b/drivers/net/ethernet/ibm/ibmvnic.c
index cdf5251e5679..ac15dcadf4c1 100644
--- a/drivers/net/ethernet/ibm/ibmvnic.c
+++ b/drivers/net/ethernet/ibm/ibmvnic.c
@@ -5247,7 +5247,8 @@ static void handle_vpd_rsp(union ibmvnic_crq *crq,
 	/* copy firmware version string from vpd into adapter */
 	if ((substr + 3 + fw_level_len) <
 	    (adapter->vpd->buff + adapter->vpd->len)) {
-		strncpy((char *)adapter->fw_version, substr + 3, fw_level_len);
+		strscpy(adapter->fw_version, substr + 3,
+			sizeof(adapter->fw_version));
 	} else {
 		dev_info(dev, "FW substr extrapolated VPD buff\n");
 	}

---
base-commit: cbf3a2cb156a2c911d8f38d8247814b4c07f49a2
change-id: 20231009-strncpy-drivers-net-ethernet-ibm-ibmvnic-c-e0900ba19e56

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

Re: [PATCH] ibmvnic: replace deprecated strncpy with strscpy

[Kees Cook]

On Mon, Oct 09, 2023 at 11:19:57PM +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.
> 
> NUL-padding is not required as the buffer is already memset to 0:
> |       memset(adapter->fw_version, 0, 32);
> 
> Note that another usage of strscpy exists on the same buffer:
> |       strscpy((char *)adapter->fw_version, "N/A", sizeof(adapter->fw_version));
> 
> 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>

Thanks, this looks right to me.

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

-- 
Kees Cook

Re: [PATCH] ibmvnic: replace deprecated strncpy with strscpy

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net-next.git (main)
by David S. Miller <davem@davemloft.net>:

On Mon, 09 Oct 2023 23:19:57 +0000 you 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.
> 
> NUL-padding is not required as the buffer is already memset to 0:
> |       memset(adapter->fw_version, 0, 32);
> 
> [...]

Here is the summary with links:
  - ibmvnic: replace deprecated strncpy with strscpy
    https://git.kernel.org/netdev/net-next/c/431acee06923

You are awesome, thank you!
-- 
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