[PATCH] regmap: mdio: Reject invalid clause-22 addresses

From: Sander Vanheule
Date: Sat Jun 05 2021 - 04:34:28 EST


Currently a regmap configuration for regmap-mdio must have a register
address width of 5 bits (cf. clause-22 register access). This is not
enforced on the provided register addresses, which would enable
clause-45 MDIO bus access, if the right bit packing is used.

Prevent clause-45 access, and other invalid addresses, by verifying the
provided register address.

Cc: Andrew Lunn <andrew@xxxxxxx>
Signed-off-by: Sander Vanheule <sander@xxxxxxxxxxxxx>
---
drivers/base/regmap/regmap-mdio.c | 15 ++++++++++++---
1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/drivers/base/regmap/regmap-mdio.c b/drivers/base/regmap/regmap-mdio.c
index 5ec208279913..3b842cf1eef9 100644
--- a/drivers/base/regmap/regmap-mdio.c
+++ b/drivers/base/regmap/regmap-mdio.c
@@ -5,16 +5,22 @@
#include <linux/module.h>
#include <linux/regmap.h>

+#define REGVAL_MASK GENMASK(15, 0)
+#define REGNUM_C22_MASK GENMASK(4, 0)
+
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);
+ if (unlikely(reg & ~REGNUM_C22_MASK))
+ return -ENXIO;
+
+ ret = mdiobus_read(mdio_dev->bus, mdio_dev->addr, reg & REGNUM_C22_MASK);
if (ret < 0)
return ret;

- *val = ret & 0xffff;
+ *val = ret & REGVAL_MASK;
return 0;
}

@@ -22,7 +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, val);
+ if (unlikely(reg & ~REGNUM_C22_MASK))
+ return -ENXIO;
+
+ return mdiobus_write(mdio_dev->bus, mdio_dev->addr, reg & REGNUM_C22_MASK, val);
}

static const struct regmap_bus regmap_mdio_bus = {
--
2.31.1