[Intel-wired-lan] [PATCH] igc: replace deprecated strncpy with strscpy

[Intel-wired-lan] [PATCH] igc: 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:
|       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: linux-hardening@vger.kernel.org
Signed-off-by: Justin Stitt <justinstitt@google.com>
---
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 <justinstitt@google.com>

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Re: [Intel-wired-lan] [PATCH] igc: replace deprecated strncpy with strscpy

[Jesse Brandeburg]

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.


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Re: [Intel-wired-lan] [PATCH] igc: replace deprecated strncpy with strscpy

[Justin Stitt]

On Tue, Oct 10, 2023 at 2:22 PM Jesse Brandeburg
<jesse.brandeburg@intel.com> 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
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Re: [Intel-wired-lan] [PATCH] igc: replace deprecated strncpy with strscpy

[Justin Stitt]

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: linux-hardening@vger.kernel.org
> Signed-off-by: Justin Stitt <justinstitt@google.com>
> ---
> 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 <justinstitt@google.com>
>
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/
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