net: mdio: C22 is now optional, EOPNOTSUPP if not provided

[ Upstream commit b063b1924fd9bf0bc157cf644764dc2151d04ccc ]

When performing a C22 operation, check that the bus driver actually
provides the methods, and return -EOPNOTSUPP if not. C45 only busses
do exist, and in future their C22 methods will be NULL.

Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Michael Walle <michael@walle.cc>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Stable-dep-of: 0e629694126c ("net/mdiobus: Fix potential out-of-bounds read/write access")
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/net/phy/mdio_bus.c b/drivers/net/phy/mdio_bus.c
index 5f89828fd9f17119bf68126cc5af1f4c5f7157a3..c26f46c06a1b2b439738c10b5732a82437572618 100644 (file)
--- a/drivers/net/phy/mdio_bus.c
+++ b/drivers/net/phy/mdio_bus.c
@@ -757,7 +757,10 @@ int __mdiobus_read(struct mii_bus *bus, int addr, u32 regnum)
 
        lockdep_assert_held_once(&bus->mdio_lock);
 
-       retval = bus->read(bus, addr, regnum);
+       if (bus->read)
+               retval = bus->read(bus, addr, regnum);
+       else
+               retval = -EOPNOTSUPP;
 
        trace_mdio_access(bus, 1, addr, regnum, retval, retval);
        mdiobus_stats_acct(&bus->stats[addr], true, retval);
@@ -783,7 +786,10 @@ int __mdiobus_write(struct mii_bus *bus, int addr, u32 regnum, u16 val)
 
        lockdep_assert_held_once(&bus->mdio_lock);
 
-       err = bus->write(bus, addr, regnum, val);
+       if (bus->write)
+               err = bus->write(bus, addr, regnum, val);
+       else
+               err = -EOPNOTSUPP;
 
        trace_mdio_access(bus, 0, addr, regnum, val, err);
        mdiobus_stats_acct(&bus->stats[addr], false, err);