`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:
| if (q_vector->rx.ring && q_vector->tx.ring)
| sprintf(q_vector->name, "%s-TxRx-%u", netdev->name,
Furthermore, we do not need NUL-padding as netdev is already
zero-allocated:
| netdev = alloc_etherdev_mq(sizeof(struct igc_adapter),
| IGC_MAX_TX_QUEUES);
...
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.
Let's also opt for the more idiomatic strscpy usage of (dest, src,
sizeof(dest)) instead of (dest, src, SOME_LEN).
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/igc/igc_main.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/net/ethernet/intel/igc/igc_main.c b/drivers/net/ethernet/intel/igc/igc_main.c
index 98de34d0ce07..e9bb403bbacf 100644
--- a/drivers/net/ethernet/intel/igc/igc_main.c
+++ b/drivers/net/ethernet/intel/igc/igc_main.c
@@ -6935,7 +6935,7 @@ static int igc_probe(struct pci_dev *pdev,
*/
igc_get_hw_control(adapter);
- strncpy(netdev->name, "eth%d", IFNAMSIZ);
+ strscpy(netdev->name, "eth%d", sizeof(netdev->name));
err = register_netdev(netdev);
if (err)
goto err_register;
---
base-commit: cbf3a2cb156a2c911d8f38d8247814b4c07f49a2
change-id: 20231010-strncpy-drivers-net-ethernet-intel-igc-igc_main-c-26efa209ddb5
Best regards,
--
Justin Stitt <[email protected]>
On 10/10/2023 2:15 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 expect netdev->name to be NUL-terminated based on its use with format
> strings:
> | if (q_vector->rx.ring && q_vector->tx.ring)
> | sprintf(q_vector->name, "%s-TxRx-%u", netdev->name,
>
> Furthermore, we do not need NUL-padding as netdev is already
> zero-allocated:
> | netdev = alloc_etherdev_mq(sizeof(struct igc_adapter),
> | IGC_MAX_TX_QUEUES);
> ...
> 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.
>
> Let's also opt for the more idiomatic strscpy usage of (dest, src,
> sizeof(dest)) instead of (dest, src, SOME_LEN).
>
Please see my comments on the igbvf patch.
On Tue, Oct 10, 2023 at 2:22 PM Jesse Brandeburg
<[email protected]> wrote:
>
> On 10/10/2023 2:15 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 expect netdev->name to be NUL-terminated based on its use with format
> > strings:
> > | if (q_vector->rx.ring && q_vector->tx.ring)
> > | sprintf(q_vector->name, "%s-TxRx-%u", netdev->name,
> >
> > Furthermore, we do not need NUL-padding as netdev is already
> > zero-allocated:
> > | netdev = alloc_etherdev_mq(sizeof(struct igc_adapter),
> > | IGC_MAX_TX_QUEUES);
> > ...
> > 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.
> >
> > Let's also opt for the more idiomatic strscpy usage of (dest, src,
> > sizeof(dest)) instead of (dest, src, SOME_LEN).
> >
>
>
> Please see my comments on the igbvf patch.
Ah, I sent too many before checking back in. I see
your comments now. Responded over there!
>
>
Thanks
Justin
On Tue, Oct 10, 2023 at 09:15:39PM +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:
> | if (q_vector->rx.ring && q_vector->tx.ring)
> | sprintf(q_vector->name, "%s-TxRx-%u", netdev->name,
>
> Furthermore, we do not need NUL-padding as netdev is already
> zero-allocated:
> | netdev = alloc_etherdev_mq(sizeof(struct igc_adapter),
> | IGC_MAX_TX_QUEUES);
> ...
> 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.
>
> Let's also opt for the more idiomatic strscpy usage of (dest, src,
> sizeof(dest)) instead of (dest, src, SOME_LEN).
>
> 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/igc/igc_main.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/net/ethernet/intel/igc/igc_main.c b/drivers/net/ethernet/intel/igc/igc_main.c
> index 98de34d0ce07..e9bb403bbacf 100644
> --- a/drivers/net/ethernet/intel/igc/igc_main.c
> +++ b/drivers/net/ethernet/intel/igc/igc_main.c
> @@ -6935,7 +6935,7 @@ static int igc_probe(struct pci_dev *pdev,
> */
> igc_get_hw_control(adapter);
>
> - strncpy(netdev->name, "eth%d", IFNAMSIZ);
> + strscpy(netdev->name, "eth%d", sizeof(netdev->name));
> err = register_netdev(netdev);
> if (err)
> goto err_register;
>
> ---
> base-commit: cbf3a2cb156a2c911d8f38d8247814b4c07f49a2
> change-id: 20231010-strncpy-drivers-net-ethernet-intel-igc-igc_main-c-26efa209ddb5
>
> 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/