netdev - [PATCH net-next 8/9] igbvf: replace deprecated strncpy with strscpy

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Message-ID: <20231017190411.2199743-9-jacob.e.keller@intel.com>
Date: Tue, 17 Oct 2023 12:04:10 -0700
From: Jacob Keller <jacob.e.keller@...el.com>
To: netdev@...r.kernel.org,
	David Miller <davem@...emloft.net>,
	Jakub Kicinski <kuba@...nel.org>
Cc: Justin Stitt <justinstitt@...gle.com>,
	linux-hardening@...r.kernel.org,
	Pucha Himasekhar Reddy <himasekharx.reddy.pucha@...el.com>,
	Jacob Keller <jacob.e.keller@...el.com>
Subject: [PATCH net-next 8/9] igbvf: replace deprecated strncpy with strscpy

From: Justin Stitt <justinstitt@...gle.com>

`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 usage with
`strlen` and format strings:
|       if (strlen(netdev->name) < (IFNAMSIZ - 5)) {
|               sprintf(adapter->tx_ring->name, "%s-tx-0", netdev->name);

Moreover, we do not need NUL-padding as netdev is already
zero-allocated:
|       netdev = alloc_etherdev(sizeof(struct igbvf_adapter));
...
alloc_etherdev() -> alloc_etherdev_mq() -> alloc_etherdev_mqs() ->
alloc_netdev_mqs() ...
|       p = kvzalloc(alloc_size, GFP_KERNEL_ACCOUNT | __GFP_RETRY_MAYFAIL);

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@...r.kernel.org
Signed-off-by: Justin Stitt <justinstitt@...gle.com>
Tested-by: Pucha Himasekhar Reddy <himasekharx.reddy.pucha@...el.com> (A Contingent worker at Intel)
Signed-off-by: Jacob Keller <jacob.e.keller@...el.com>
---
 drivers/net/ethernet/intel/igbvf/netdev.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/intel/igbvf/netdev.c b/drivers/net/ethernet/intel/igbvf/netdev.c
index 7ff2752dd763..fd712585af27 100644
--- a/drivers/net/ethernet/intel/igbvf/netdev.c
+++ b/drivers/net/ethernet/intel/igbvf/netdev.c
@@ -2785,7 +2785,7 @@ static int igbvf_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 
 	igbvf_set_ethtool_ops(netdev);
 	netdev->watchdog_timeo = 5 * HZ;
-	strncpy(netdev->name, pci_name(pdev), sizeof(netdev->name) - 1);
+	strscpy(netdev->name, pci_name(pdev), sizeof(netdev->name));
 
 	adapter->bd_number = cards_found++;
 
-- 
2.41.0