strncpy() is deprecated for use on NUL-terminated destination strings
[1] and as such we should prefer more robust and less ambiguous string
interfaces.

ethtool_sprintf() is designed specifically for get_strings() usage.
Let's replace strncpy() in favor of this more robust and easier to
understand interface.

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/microchip/sparx5/sparx5_ethtool.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/microchip/sparx5/sparx5_ethtool.c b/drivers/net/ethernet/microchip/sparx5/sparx5_ethtool.c
index 01f3a3a41cdb..37d2584b48a7 100644
--- a/drivers/net/ethernet/microchip/sparx5/sparx5_ethtool.c
+++ b/drivers/net/ethernet/microchip/sparx5/sparx5_ethtool.c
@@ -1012,8 +1012,7 @@ static void sparx5_get_sset_strings(struct net_device *ndev, u32 sset, u8 *data)
 		return;
 
 	for (idx = 0; idx < sparx5->num_ethtool_stats; idx++)
-		strncpy(data + idx * ETH_GSTRING_LEN,
-			sparx5->stats_layout[idx], ETH_GSTRING_LEN);
+		ethtool_sprintf(&data, "%s", sparx5->stats_layout[idx]);
 }
 
 static void sparx5_get_sset_data(struct net_device *ndev,

---
base-commit: cbf3a2cb156a2c911d8f38d8247814b4c07f49a2
change-id: 20231011-strncpy-drivers-net-ethernet-microchip-sparx5-sparx5_ethtool-c-793896db6cf4

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

Hello:

This patch was applied to netdev/net-next.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Wed, 11 Oct 2023 21:37:18 +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.
> 
> ethtool_sprintf() is designed specifically for get_strings() usage.
> Let's replace strncpy() in favor of this more robust and easier to
> understand interface.
> 
> [...]

Here is the summary with links:
  - net: sparx5: replace deprecated strncpy with ethtool_sprintf
    https://git.kernel.org/netdev/net-next/c/e343023e03d2

You are awesome, thank you!
-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html

On Wed, Oct 11, 2023 at 09:37:18PM +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.
> 
> ethtool_sprintf() is designed specifically for get_strings() usage.
> Let's replace strncpy() in favor of this more robust and easier to
> understand interface.
> 
> 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>

Another direct ethtool_sprintf() replacement. Thanks!

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

-- 
Kees Cook