linux-hardening - [PATCH] net/mlx5: simplify mlx5_set_driver

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Message-ID: <20231011-strncpy-drivers-net-ethernet-mellanox-mlx5-core-main-c-v1-1-90fa39998bb2@google.com>
Date: Wed, 11 Oct 2023 21:29:57 +0000
From: Justin Stitt <justinstitt@...gle.com>
To: Saeed Mahameed <saeedm@...dia.com>, Leon Romanovsky <leon@...nel.org>, 
	"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, 
	Kees Cook <keescook@...omium.org>, Justin Stitt <justinstitt@...gle.com>
Subject: [PATCH] net/mlx5: simplify mlx5_set_driver_version string assignments

In total, just assigning this version string takes:
(1) strncpy()'s
(5) strlen()'s
(3) strncat()'s
(1) snprintf()'s
(4) max_t()'s

Moreover, `strncpy` is deprecated [1] and `strncat` really shouldn't be
used either [2]. With this in mind, let's simply use a single
`snprintf`.

Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
Link: https://elixir.bootlin.com/linux/v6.6-rc5/source/include/linux/fortify-string.h#L448 [2]
Link: https://github.com/KSPP/linux/issues/90
Cc: linux-hardening@...r.kernel.org
Cc: Kees Cook <keescook@...omium.org>
Signed-off-by: Justin Stitt <justinstitt@...gle.com>
---
Note: build-tested only.

Found with: $ rg "strncpy\("
---
 drivers/net/ethernet/mellanox/mlx5/core/main.c | 20 +++-----------------
 1 file changed, 3 insertions(+), 17 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/main.c b/drivers/net/ethernet/mellanox/mlx5/core/main.c
index 15561965d2af..0c829b6d2b49 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/main.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/main.c
@@ -218,7 +218,6 @@ static void mlx5_set_driver_version(struct mlx5_core_dev *dev)
 	int driver_ver_sz = MLX5_FLD_SZ_BYTES(set_driver_version_in,
 					      driver_version);
 	u8 in[MLX5_ST_SZ_BYTES(set_driver_version_in)] = {};
-	int remaining_size = driver_ver_sz;
 	char *string;
 
 	if (!MLX5_CAP_GEN(dev, driver_version))
@@ -226,22 +225,9 @@ static void mlx5_set_driver_version(struct mlx5_core_dev *dev)
 
 	string = MLX5_ADDR_OF(set_driver_version_in, in, driver_version);
 
-	strncpy(string, "Linux", remaining_size);
-
-	remaining_size = max_t(int, 0, driver_ver_sz - strlen(string));
-	strncat(string, ",", remaining_size);
-
-	remaining_size = max_t(int, 0, driver_ver_sz - strlen(string));
-	strncat(string, KBUILD_MODNAME, remaining_size);
-
-	remaining_size = max_t(int, 0, driver_ver_sz - strlen(string));
-	strncat(string, ",", remaining_size);
-
-	remaining_size = max_t(int, 0, driver_ver_sz - strlen(string));
-
-	snprintf(string + strlen(string), remaining_size, "%u.%u.%u",
-		LINUX_VERSION_MAJOR, LINUX_VERSION_PATCHLEVEL,
-		LINUX_VERSION_SUBLEVEL);
+	snprintf(string, driver_ver_sz, "Linux,%s,%u.%u.%u",
+		 KBUILD_MODNAME, LINUX_VERSION_MAJOR,
+		 LINUX_VERSION_PATCHLEVEL, LINUX_VERSION_SUBLEVEL);
 
 	/*Send the command*/
 	MLX5_SET(set_driver_version_in, in, opcode,

---
base-commit: cbf3a2cb156a2c911d8f38d8247814b4c07f49a2
change-id: 20231011-strncpy-drivers-net-ethernet-mellanox-mlx5-core-main-c-2dd9a3fa22e0

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