linux-hardening - [PATCH] net/mlx4_core: replace deprecated strncpy with strscpy

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Message-ID: <20231011-strncpy-drivers-net-ethernet-mellanox-mlx4-fw-c-v1-1-4d7b5d34c933@google.com>
Date: Wed, 11 Oct 2023 21:04:37 +0000
From: Justin Stitt <justinstitt@...gle.com>
To: Tariq Toukan <tariqt@...dia.com>, "David S. Miller" <davem@...emloft.net>, 
	Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>
Cc: netdev@...r.kernel.org, linux-rdma@...r.kernel.org, 
	linux-kernel@...r.kernel.org, linux-hardening@...r.kernel.org, 
	Justin Stitt <justinstitt@...gle.com>
Subject: [PATCH] net/mlx4_core: replace deprecated strncpy with strscpy

`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 `dst` to be NUL-terminated based on its use with format
strings:
|       mlx4_dbg(dev, "Reporting Driver Version to FW: %s\n", dst);

Moreover, NUL-padding is not required.

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@...r.kernel.org
Signed-off-by: Justin Stitt <justinstitt@...gle.com>
---
Note: build-tested only.

Found with: $ rg "strncpy\("
---
 drivers/net/ethernet/mellanox/mlx4/fw.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/mellanox/mlx4/fw.c b/drivers/net/ethernet/mellanox/mlx4/fw.c
index fe48d20d6118..0005d9e2c2d6 100644
--- a/drivers/net/ethernet/mellanox/mlx4/fw.c
+++ b/drivers/net/ethernet/mellanox/mlx4/fw.c
@@ -1967,7 +1967,7 @@ int mlx4_INIT_HCA(struct mlx4_dev *dev, struct mlx4_init_hca_param *param)
 	if (dev->caps.flags2 & MLX4_DEV_CAP_FLAG2_DRIVER_VERSION_TO_FW) {
 		u8 *dst = (u8 *)(inbox + INIT_HCA_DRIVER_VERSION_OFFSET / 4);
 
-		strncpy(dst, DRV_NAME_FOR_FW, INIT_HCA_DRIVER_VERSION_SZ - 1);
+		strscpy(dst, DRV_NAME_FOR_FW, INIT_HCA_DRIVER_VERSION_SZ);
 		mlx4_dbg(dev, "Reporting Driver Version to FW: %s\n", dst);
 	}
 

---
base-commit: cbf3a2cb156a2c911d8f38d8247814b4c07f49a2
change-id: 20231011-strncpy-drivers-net-ethernet-mellanox-mlx4-fw-c-67809559dd1a

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