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

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Message-ID: <20231009-strncpy-drivers-net-ethernet-ibm-ibmvnic-c-v1-1-712866f16754@google.com>
Date: Mon, 09 Oct 2023 23:19:57 +0000
From: Justin Stitt <justinstitt@...gle.com>
To: Michael Ellerman <mpe@...erman.id.au>, Nicholas Piggin <npiggin@...il.com>, 
	Christophe Leroy <christophe.leroy@...roup.eu>, Haren Myneni <haren@...ux.ibm.com>, 
	Rick Lindsley <ricklind@...ux.ibm.com>, Nick Child <nnac123@...ux.ibm.com>, 
	Dany Madden <danymadden@...ibm.com>, Thomas Falcon <tlfalcon@...ux.ibm.com>, 
	"David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, 
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>
Cc: linuxppc-dev@...ts.ozlabs.org, netdev@...r.kernel.org, 
	linux-kernel@...r.kernel.org, linux-hardening@...r.kernel.org, 
	Justin Stitt <justinstitt@...gle.com>
Subject: [PATCH] ibmvnic: 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.

NUL-padding is not required as the buffer is already memset to 0:
|       memset(adapter->fw_version, 0, 32);

Note that another usage of strscpy exists on the same buffer:
|       strscpy((char *)adapter->fw_version, "N/A", sizeof(adapter->fw_version));

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.
---
 drivers/net/ethernet/ibm/ibmvnic.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/ibm/ibmvnic.c b/drivers/net/ethernet/ibm/ibmvnic.c
index cdf5251e5679..ac15dcadf4c1 100644
--- a/drivers/net/ethernet/ibm/ibmvnic.c
+++ b/drivers/net/ethernet/ibm/ibmvnic.c
@@ -5247,7 +5247,8 @@ static void handle_vpd_rsp(union ibmvnic_crq *crq,
 	/* copy firmware version string from vpd into adapter */
 	if ((substr + 3 + fw_level_len) <
 	    (adapter->vpd->buff + adapter->vpd->len)) {
-		strncpy((char *)adapter->fw_version, substr + 3, fw_level_len);
+		strscpy(adapter->fw_version, substr + 3,
+			sizeof(adapter->fw_version));
 	} else {
 		dev_info(dev, "FW substr extrapolated VPD buff\n");
 	}

---
base-commit: cbf3a2cb156a2c911d8f38d8247814b4c07f49a2
change-id: 20231009-strncpy-drivers-net-ethernet-ibm-ibmvnic-c-e0900ba19e56

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