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 e9303be486556580506cf84611c1f643b6967178..743a63eca7840fd5e8aecce4122897dd2fa48e7b 100644 (file)
--- a/drivers/net/phy/mdio_bus.c
+++ b/drivers/net/phy/mdio_bus.c
@@ -754,7 +754,10 @@ int __mdiobus_read(struct mii_bus *bus, int addr, u32 regnum)
 
        WARN_ON_ONCE(!mutex_is_locked(&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);
@@ -780,7 +783,10 @@ int __mdiobus_write(struct mii_bus *bus, int addr, u32 regnum, u16 val)
 
        WARN_ON_ONCE(!mutex_is_locked(&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);