linux-hardening - [PATCH] net: phy: smsc: replace deprecated strncpy with ethtool

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Message-ID: <20231012-strncpy-drivers-net-phy-smsc-c-v1-1-00528f7524b3@google.com>
Date: Thu, 12 Oct 2023 22:27:52 +0000
From: Justin Stitt <justinstitt@...gle.com>
To: Andrew Lunn <andrew@...n.ch>, Heiner Kallweit <hkallweit1@...il.com>, 
	Russell King <linux@...linux.org.uk>, "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: phy: smsc: replace deprecated strncpy with ethtool_sprintf

strncpy() is deprecated for use on NUL-terminated destination strings
[1] and as such we should prefer more robust and less ambiguous string
interfaces.

ethtool_sprintf() is designed specifically for get_strings() usage.
Let's replace strncpy in favor of this dedicated helper function.

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/net/phy/smsc.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/drivers/net/phy/smsc.c b/drivers/net/phy/smsc.c
index c88edb19d2e7..1c7306a1af13 100644
--- a/drivers/net/phy/smsc.c
+++ b/drivers/net/phy/smsc.c
@@ -507,10 +507,8 @@ static void smsc_get_strings(struct phy_device *phydev, u8 *data)
 {
 	int i;
 
-	for (i = 0; i < ARRAY_SIZE(smsc_hw_stats); i++) {
-		strncpy(data + i * ETH_GSTRING_LEN,
-		       smsc_hw_stats[i].string, ETH_GSTRING_LEN);
-	}
+	for (i = 0; i < ARRAY_SIZE(smsc_hw_stats); i++)
+		ethtool_sprintf(&data, "%s", smsc_hw_stats[i].string);
 }
 
 static u64 smsc_get_stat(struct phy_device *phydev, int i)

---
base-commit: cbf3a2cb156a2c911d8f38d8247814b4c07f49a2
change-id: 20231012-strncpy-drivers-net-phy-smsc-c-75dff87bab53

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