diff mbox series

igbvf: replace deprecated strncpy with strscpy

Message ID 20231010-strncpy-drivers-net-ethernet-intel-igbvf-netdev-c-v1-1-69ccfb2c2aa5@google.com
State Superseded
Headers show
Series igbvf: replace deprecated strncpy with strscpy | expand

Commit Message

Justin Stitt Oct. 10, 2023, 9:12 p.m. UTC 
`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@vger.kernel.org
Signed-off-by: Justin Stitt <justinstitt@google.com>
---
Note: build-tested only.
---
 drivers/net/ethernet/intel/igbvf/netdev.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)


---
base-commit: cbf3a2cb156a2c911d8f38d8247814b4c07f49a2
change-id: 20231010-strncpy-drivers-net-ethernet-intel-igbvf-netdev-c-aea454a18a2d

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

Comments

Justin Stitt Oct. 10, 2023, 9:41 p.m. UTC | #1 
On Tue, Oct 10, 2023 at 2:20 PM Jesse Brandeburg
<jesse.brandeburg@intel.com> wrote:
>
> On 10/10/2023 2:12 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 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@vger.kernel.org
> > Signed-off-by: Justin Stitt <justinstitt@google.com>
> > ---
>
> Thanks Justin for these patches, please make sure you mark the subject
> line as per the netdev rules:
> [PATCH net-next v1] etc etc

Sure, I'll resend!

>
> I'd also prefer they came in as part of one series with a good cover
> letter, at the very least for the Intel drivers, and you probably could
> combine any others (netdev) together up to the 15 patch limit.

Got it :)

>
> Please mention how you found these issues, via automated tool or via
> coccinelle script, manual grepping, etc?

rg "strncpy\(" > pain.txt

>
> Thanks,
> Jesse
>
Justin Stitt Oct. 10, 2023, 10:41 p.m. UTC | #2 
On Tue, Oct 10, 2023 at 09:12:00PM +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 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@vger.kernel.org
> Signed-off-by: Justin Stitt <justinstitt@google.com>
> ---
> Note: build-tested only.
> ---
>  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++;
>
>
> ---
> base-commit: cbf3a2cb156a2c911d8f38d8247814b4c07f49a2
> change-id: 20231010-strncpy-drivers-net-ethernet-intel-igbvf-netdev-c-aea454a18a2d
>
> 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/
diff mbox series

Patch

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++;