[PATCH] net: atheros: replace deprecated strncpy with strscpy

[PATCH] net: atheros: 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.

We expect netdev->name to be NUL-terminated based on its use with format
strings and dev_info():
|     dev_info(&adapter->pdev->dev,
|             "%s link is up %d Mbps %s\n",
|             netdev->name, adapter->link_speed,
|             adapter->link_duplex == FULL_DUPLEX ?
|             "full duplex" : "half duplex");

Furthermore, NUL-padding is not required as netdev is already
zero-initialized through alloc_etherdev().

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/atheros/atlx/atl2.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/atheros/atlx/atl2.c b/drivers/net/ethernet/atheros/atlx/atl2.c
index 1b487c071cb6..bcfc9488125b 100644
--- a/drivers/net/ethernet/atheros/atlx/atl2.c
+++ b/drivers/net/ethernet/atheros/atlx/atl2.c
@@ -1377,7 +1377,7 @@ static int atl2_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 	netdev->watchdog_timeo = 5 * HZ;
 	netdev->min_mtu = 40;
 	netdev->max_mtu = ETH_DATA_LEN + VLAN_HLEN;
-	strncpy(netdev->name, pci_name(pdev), sizeof(netdev->name) - 1);
+	strscpy(netdev->name, pci_name(pdev), sizeof(netdev->name));
 
 	netdev->mem_start = mmio_start;
 	netdev->mem_end = mmio_start + mmio_len;

---
base-commit: cbf3a2cb156a2c911d8f38d8247814b4c07f49a2
change-id: 20231005-strncpy-drivers-net-ethernet-atheros-atlx-atl2-c-d876945d6341

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

Re: [PATCH] net: atheros: replace deprecated strncpy with strscpy

[Kees Cook]

On Thu, Oct 05, 2023 at 01:29:45AM +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 netdev->name to be NUL-terminated based on its use with format
> strings and dev_info():
> |     dev_info(&adapter->pdev->dev,
> |             "%s link is up %d Mbps %s\n",
> |             netdev->name, adapter->link_speed,
> |             adapter->link_duplex == FULL_DUPLEX ?
> |             "full duplex" : "half duplex");
> 
> Furthermore, NUL-padding is not required as netdev is already
> zero-initialized through alloc_etherdev().
> 
> 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>

Looks right; destination length correctly updated.

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

-- 
Kees Cook

Re: [PATCH] net: atheros: replace deprecated strncpy with strscpy

[patchwork-bot+netdevbpf]

Hello:

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

On Thu, 05 Oct 2023 01:29:45 +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.
> 
> We expect netdev->name to be NUL-terminated based on its use with format
> strings and dev_info():
> |     dev_info(&adapter->pdev->dev,
> |             "%s link is up %d Mbps %s\n",
> |             netdev->name, adapter->link_speed,
> |             adapter->link_duplex == FULL_DUPLEX ?
> |             "full duplex" : "half duplex");
> 
> [...]

Here is the summary with links:
  - net: atheros: replace deprecated strncpy with strscpy
    https://git.kernel.org/netdev/net-next/c/9814ec70fccb

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