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

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Message-ID: <20231005-strncpy-drivers-net-ethernet-cavium-liquidio-lio_main-c-v1-1-663e3f1d8f99@google.com>
Date: Thu, 05 Oct 2023 21:41:01 +0000
From: Justin Stitt <justinstitt@...gle.com>
To: Derek Chickles <dchickles@...vell.com>, Satanand Burla <sburla@...vell.com>, 
	Felix Manlunas <fmanlunas@...vell.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-kernel@...r.kernel.org, 
	linux-hardening@...r.kernel.org, Justin Stitt <justinstitt@...gle.com>
Subject: [PATCH] net: liquidio: replace deprecated strncpy with strscpy_pad

`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 know `fw_type` must be NUL-terminated based on use here:
|       static bool fw_type_is_auto(void)
|       {
|       	return strncmp(fw_type, LIO_FW_NAME_TYPE_AUTO,
|       		       sizeof(LIO_FW_NAME_TYPE_AUTO)) == 0;
|       }
...and here
|       module_param_string(fw_type, fw_type, sizeof(fw_type), 0444);

Let's opt to NUL-pad the destination buffer as well so that we maintain
the same exact behavior that `strncpy` provided here.

A suitable replacement is `strscpy_pad` due to the fact that it
guarantees both NUL-termination and NUL-padding on the destination
buffer.

Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
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.
---
 drivers/net/ethernet/cavium/liquidio/lio_main.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/cavium/liquidio/lio_main.c b/drivers/net/ethernet/cavium/liquidio/lio_main.c
index 100daadbea2a..34f02a8ec2ca 100644
--- a/drivers/net/ethernet/cavium/liquidio/lio_main.c
+++ b/drivers/net/ethernet/cavium/liquidio/lio_main.c
@@ -1689,7 +1689,7 @@ static int load_firmware(struct octeon_device *oct)
 
 	if (fw_type_is_auto()) {
 		tmp_fw_type = LIO_FW_NAME_TYPE_NIC;
-		strncpy(fw_type, tmp_fw_type, sizeof(fw_type));
+		strscpy_pad(fw_type, tmp_fw_type, sizeof(fw_type));
 	} else {
 		tmp_fw_type = fw_type;
 	}

---
base-commit: cbf3a2cb156a2c911d8f38d8247814b4c07f49a2
change-id: 20231005-strncpy-drivers-net-ethernet-cavium-liquidio-lio_main-c-b05f78661635

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