`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 see that netdev->name is expected to be NUL-terminated based on its
usage with format strings:
| sprintf(q_vector->name, "%s-TxRx-%u", netdev->name,
| q_vector->rx.ring->queue_index);
Furthermore, NUL-padding is not required as netdev is already
zero-allocated:
| netdev = alloc_etherdev_mq(sizeof(struct igb_adapter),
| IGB_MAX_TX_QUEUES);
...
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: [email protected]
Signed-off-by: Justin Stitt <[email protected]>
---
Note: build-tested only.
---
drivers/net/ethernet/intel/igb/igb_main.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/net/ethernet/intel/igb/igb_main.c b/drivers/net/ethernet/intel/igb/igb_main.c
index 76b34cee1da3..9de103bd3ad3 100644
--- a/drivers/net/ethernet/intel/igb/igb_main.c
+++ b/drivers/net/ethernet/intel/igb/igb_main.c
@@ -3264,7 +3264,7 @@ static int igb_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
igb_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));
netdev->mem_start = pci_resource_start(pdev, 0);
netdev->mem_end = pci_resource_end(pdev, 0);
---
base-commit: cbf3a2cb156a2c911d8f38d8247814b4c07f49a2
change-id: 20231010-strncpy-drivers-net-ethernet-intel-igb-igb_main-c-b259e3f289d3
Best regards,
--
Justin Stitt <[email protected]>
On 10/10/2023 2:07 PM, 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 see that netdev->name is expected to be NUL-terminated based on its
> usage with format strings:
> | sprintf(q_vector->name, "%s-TxRx-%u", netdev->name,
> | q_vector->rx.ring->queue_index);
>
> Furthermore, NUL-padding is not required as netdev is already
> zero-allocated:
> | netdev = alloc_etherdev_mq(sizeof(struct igb_adapter),
> | IGB_MAX_TX_QUEUES);
> ...
> 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.
Please see my comments on the igbvf patch.
On Tue, Oct 10, 2023 at 09:07:59PM +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 see that netdev->name is expected to be NUL-terminated based on its
> usage with format strings:
> | sprintf(q_vector->name, "%s-TxRx-%u", netdev->name,
> | q_vector->rx.ring->queue_index);
>
> Furthermore, NUL-padding is not required as netdev is already
> zero-allocated:
> | netdev = alloc_etherdev_mq(sizeof(struct igb_adapter),
> | IGB_MAX_TX_QUEUES);
> ...
> 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: [email protected]
> Signed-off-by: Justin Stitt <[email protected]>
> ---
> Note: build-tested only.
> ---
> drivers/net/ethernet/intel/igb/igb_main.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/net/ethernet/intel/igb/igb_main.c b/drivers/net/ethernet/intel/igb/igb_main.c
> index 76b34cee1da3..9de103bd3ad3 100644
> --- a/drivers/net/ethernet/intel/igb/igb_main.c
> +++ b/drivers/net/ethernet/intel/igb/igb_main.c
> @@ -3264,7 +3264,7 @@ static int igb_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
> igb_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));
>
> netdev->mem_start = pci_resource_start(pdev, 0);
> netdev->mem_end = pci_resource_end(pdev, 0);
>
> ---
> base-commit: cbf3a2cb156a2c911d8f38d8247814b4c07f49a2
> change-id: 20231010-strncpy-drivers-net-ethernet-intel-igb-igb_main-c-b259e3f289d3
>
> Best regards,
> --
> Justin Stitt <[email protected]>
>
Hi, this patch was bundled up with some others. It has a new home:
https://lore.kernel.org/all/20231010-netdev-replace-strncpy-resend-as-series-v1-0-caf9f0f2f021@google.com/