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

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Message-ID: <20231030-strncpy-drivers-scsi-ibmvscsi-ibmvscsi-c-v1-1-f8b06ae9e3d5@google.com>
Date: Mon, 30 Oct 2023 20:40:48 +0000
From: Justin Stitt <justinstitt@...gle.com>
To: Tyrel Datwyler <tyreld@...ux.ibm.com>, Michael Ellerman <mpe@...erman.id.au>, 
	Nicholas Piggin <npiggin@...il.com>, Christophe Leroy <christophe.leroy@...roup.eu>, 
	"James E.J. Bottomley" <jejb@...ux.ibm.com>, "Martin K. Petersen" <martin.petersen@...cle.com>
Cc: linux-scsi@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org, 
	linux-kernel@...r.kernel.org, linux-hardening@...r.kernel.org, 
	Justin Stitt <justinstitt@...gle.com>
Subject: [PATCH] scsi: ibmvscsi: 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 partition_name to be NUL-terminated based on its usage with
format strings:
|       dev_info(hostdata->dev, "host srp version: %s, "
|                "host partition %s (%d), OS %d, max io %u\n",
|                hostdata->madapter_info.srp_version,
|                hostdata->madapter_info.partition_name,
|                be32_to_cpu(hostdata->madapter_info.partition_number),
|                be32_to_cpu(hostdata->madapter_info.os_type),
|                be32_to_cpu(hostdata->madapter_info.port_max_txu[0]));
...
|       len = snprintf(buf, PAGE_SIZE, "%s\n",
|                hostdata->madapter_info.partition_name);

Moreover, NUL-padding is not required as madapter_info is explicitly
memset to 0:
|       memset(&hostdata->madapter_info, 0x00,
|                       sizeof(hostdata->madapter_info));

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/scsi/ibmvscsi/ibmvscsi.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/scsi/ibmvscsi/ibmvscsi.c b/drivers/scsi/ibmvscsi/ibmvscsi.c
index 59599299615d..71f3e9563520 100644
--- a/drivers/scsi/ibmvscsi/ibmvscsi.c
+++ b/drivers/scsi/ibmvscsi/ibmvscsi.c
@@ -266,7 +266,7 @@ static void set_adapter_info(struct ibmvscsi_host_data *hostdata)
 	dev_info(hostdata->dev, "SRP_VERSION: %s\n", SRP_VERSION);
 	strcpy(hostdata->madapter_info.srp_version, SRP_VERSION);
 
-	strncpy(hostdata->madapter_info.partition_name, partition_name,
+	strscpy(hostdata->madapter_info.partition_name, partition_name,
 			sizeof(hostdata->madapter_info.partition_name));
 
 	hostdata->madapter_info.partition_number =

---
base-commit: ffc253263a1375a65fa6c9f62a893e9767fbebfa
change-id: 20231030-strncpy-drivers-scsi-ibmvscsi-ibmvscsi-c-3b5019ce50ad

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