linux-kernel - [PATCH 2/2] regmap: mdio: Reject invalid clause-22 addresses

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Message-Id: <7e1fc137134699fd2daca0937c2223225afd9c3d.1623238313.git.sander@svanheule.net>
Date:   Wed,  9 Jun 2021 13:46:06 +0200
From:   Sander Vanheule <sander@...nheule.net>
To:     Mark Brown <broonie@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J . Wysocki" <rafael@...nel.org>,
        linux-kernel@...r.kernel.org
Cc:     Andy Shevchenko <andy.shevchenko@...il.com>,
        Adrew Lunn <andrew@...n.ch>,
        Sander Vanheule <sander@...nheule.net>
Subject: [PATCH 2/2] regmap: mdio: Reject invalid clause-22 addresses

When an invalid register offset is provided, the upper bits are silently
discarded. Change this to return -ENXIO instead, to help catch potential
bugs.

Signed-off-by: Sander Vanheule <sander@...nheule.net>
---
 drivers/base/regmap/regmap-mdio.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/base/regmap/regmap-mdio.c b/drivers/base/regmap/regmap-mdio.c
index aee34bf2400e..9adfb82be8f1 100644
--- a/drivers/base/regmap/regmap-mdio.c
+++ b/drivers/base/regmap/regmap-mdio.c
@@ -13,7 +13,10 @@ static int regmap_mdio_read(void *context, unsigned int reg, unsigned int *val)
 	struct mdio_device *mdio_dev = context;
 	int ret;
 
-	ret = mdiobus_read(mdio_dev->bus, mdio_dev->addr, reg & REGNUM_C22_MASK);
+	if (unlikely(reg & ~REGNUM_C22_MASK))
+		return -ENXIO;
+
+	ret = mdiobus_read(mdio_dev->bus, mdio_dev->addr, reg);
 	if (ret < 0)
 		return ret;
 
@@ -25,7 +28,10 @@ static int regmap_mdio_write(void *context, unsigned int reg, unsigned int val)
 {
 	struct mdio_device *mdio_dev = context;
 
-	return mdiobus_write(mdio_dev->bus, mdio_dev->addr, reg & REGNUM_C22_MASK, val);
+	if (unlikely(reg & ~REGNUM_C22_MASK))
+		return -ENXIO;
+
+	return mdiobus_write(mdio_dev->bus, mdio_dev->addr, reg, val);
 }
 
 static const struct regmap_bus regmap_mdio_bus = {
-- 
2.31.1