linux-hardening - [PATCH] hwmon: pmbus: refactor deprecated strncpy

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Date:   Fri, 15 Sep 2023 18:28:41 +0000
From:   Justin Stitt <justinstitt@...gle.com>
To:     Guenter Roeck <linux@...ck-us.net>,
        Jean Delvare <jdelvare@...e.com>
Cc:     linux-hwmon@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-hardening@...r.kernel.org,
        Justin Stitt <justinstitt@...gle.com>
Subject: [PATCH] hwmon: pmbus: refactor deprecated strncpy

`strncpy` is deprecated for use on NUL-terminated destination strings [1].

We should prefer more robust and less ambiguous string interfaces.

A suitable replacement is `strscpy` [2] due to the fact that it guarantees
NUL-termination on the destination buffer without unnecessarily NUL-padding.

`label` is zero-allocated and as such the NUL-padding behavior of
strncpy is not required here.

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>
---
 drivers/hwmon/pmbus/pmbus_core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/hwmon/pmbus/pmbus_core.c b/drivers/hwmon/pmbus/pmbus_core.c
index 1363d9f89181..dcc8b12387cc 100644
--- a/drivers/hwmon/pmbus/pmbus_core.c
+++ b/drivers/hwmon/pmbus/pmbus_core.c
@@ -1394,7 +1394,7 @@ static int pmbus_add_label(struct pmbus_data *data,
 	snprintf(label->name, sizeof(label->name), "%s%d_label", name, seq);
 	if (!index) {
 		if (phase == 0xff)
-			strncpy(label->label, lstring,
+			strscpy(label->label, lstring,
 				sizeof(label->label) - 1);
 		else
 			snprintf(label->label, sizeof(label->label), "%s.%d",

---
base-commit: 3669558bdf354cd352be955ef2764cde6a9bf5ec
change-id: 20230915-strncpy-drivers-hwmon-pmbus-pmbus_core-c-8279663960a3

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