[PATCH v2] net: ena: replace deprecated strncpy with strscpy

[PATCH v2] net: ena: replace deprecated strncpy with strscpy

[justinstitt]

`strncpy` is deprecated for use on NUL-terminated destination strings
[1] and as such we should prefer more robust and less ambiguous string
interfaces.

A suitable replacement is `strscpy` [2] due to the fact that it
guarantees NUL-termination on the destination buffer without
unnecessarily NUL-padding.

host_info allocation is done in ena_com_allocate_host_info() via
dma_alloc_coherent() and is not zero initialized by alloc_etherdev_mq().

However zero initialization of the destination doesn't matter in this case,
because strscpy() guarantees a NULL termination.

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>
---
Changes in v2:
- update commit message, dropping inaccurate statement about allocation
  (thanks Arthur)
- copy/paste Arthur's explanation regarding host_info allocation into
- rebased onto mainline
- Link to v1: https://lore.kernel.org/r/20231005-strncpy-drivers-net-ethernet-amazon-ena-ena_netdev-c-v1-1-ba4879974160@google.com
---
Note: build-tested only.
---
 drivers/net/ethernet/amazon/ena/ena_netdev.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/amazon/ena/ena_netdev.c b/drivers/net/ethernet/amazon/ena/ena_netdev.c
index b5bca4814830..4a41efcc996b 100644
--- a/drivers/net/ethernet/amazon/ena/ena_netdev.c
+++ b/drivers/net/ethernet/amazon/ena/ena_netdev.c
@@ -3276,8 +3276,8 @@ static void ena_config_host_info(struct ena_com_dev *ena_dev, struct pci_dev *pd
 	strscpy(host_info->kernel_ver_str, utsname()->version,
 		sizeof(host_info->kernel_ver_str) - 1);
 	host_info->os_dist = 0;
-	strncpy(host_info->os_dist_str, utsname()->release,
-		sizeof(host_info->os_dist_str) - 1);
+	strscpy(host_info->os_dist_str, utsname()->release,
+		sizeof(host_info->os_dist_str));
 	host_info->driver_version =
 		(DRV_MODULE_GEN_MAJOR) |
 		(DRV_MODULE_GEN_MINOR << ENA_ADMIN_HOST_INFO_MINOR_SHIFT) |

---
base-commit: bee0e7762ad2c6025b9f5245c040fcc36ef2bde8
change-id: 20231005-strncpy-drivers-net-ethernet-amazon-ena-ena_netdev-c-6c4804466aa7

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

RE: [PATCH v2] net: ena: replace deprecated strncpy with strscpy

[Kiyanovski, Arthur]

> -----Original Message-----
> From: justinstitt@google.com <justinstitt@google.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.
> 
> A suitable replacement is `strscpy` [2] due to the fact that it guarantees NUL-
> termination on the destination buffer without unnecessarily NUL-padding.
> 
> host_info allocation is done in ena_com_allocate_host_info() via
> dma_alloc_coherent() and is not zero initialized by alloc_etherdev_mq().
> 
> However zero initialization of the destination doesn't matter in this case,
> because strscpy() guarantees a NULL termination.
> 
> 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>
> ---
> Changes in v2:
> - update commit message, dropping inaccurate statement about allocation
>   (thanks Arthur)
> - copy/paste Arthur's explanation regarding host_info allocation into
> - rebased onto mainline
> - Link to v1: https://lore.kernel.org/r/20231005-strncpy-drivers-net-ethernet-
> amazon-ena-ena_netdev-c-v1-1-ba4879974160@google.com
> ---
> Note: build-tested only.
> ---
>  ..................
> Best regards,
> --
> Justin Stitt <justinstitt@google.com>

Thanks for making the necessary changes to the commit message Justin.
Looks good.

Acked-by: Arthur Kiyanovski <akiyano@amazon.com>

Re: [PATCH v2] net: ena: replace deprecated strncpy with strscpy

[Kees Cook]

On Thu, Dec 07, 2023 at 09:34:42PM +0000, justinstitt@google.com 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.
> 
> A suitable replacement is `strscpy` [2] due to the fact that it
> guarantees NUL-termination on the destination buffer without
> unnecessarily NUL-padding.
> 
> host_info allocation is done in ena_com_allocate_host_info() via
> dma_alloc_coherent() and is not zero initialized by alloc_etherdev_mq().
> 
> However zero initialization of the destination doesn't matter in this case,
> because strscpy() guarantees a NULL termination.
> 
> 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>

Yeah, this reads much better.

Reviewed-by: Kees Cook <keescook@chromium.org>

-- 
Kees Cook

Re: [PATCH v2] net: ena: replace deprecated strncpy with strscpy

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net-next.git (main)
by David S. Miller <davem@davemloft.net>:

On Thu, 07 Dec 2023 21:34:42 +0000 you 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.
> 
> A suitable replacement is `strscpy` [2] due to the fact that it
> guarantees NUL-termination on the destination buffer without
> unnecessarily NUL-padding.
> 
> [...]

Here is the summary with links:
  - [v2] net: ena: replace deprecated strncpy with strscpy
    https://git.kernel.org/netdev/net-next/c/378bc9a40ed8

You are awesome, thank you!
-- 
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