Revert "net: mdiobus: Fix memory leak in __mdiobus_register"

commit 10eff1f5788b6ffac212c254e2f3666219576889 upstream.

This reverts commit ab609f25d19858513919369ff3d9a63c02cd9e2e.

This patch is correct in the sense that we _should_ call device_put() in
case of device_register() failure, but the problem in this code is more
vast.

We need to set bus->state to UNMDIOBUS_REGISTERED before calling
device_register() to correctly release the device in mdiobus_free().
This patch prevents us from doing it, since in case of device_register()
failure put_device() will be called 2 times and it will cause UAF or
something else.

Also, Reported-by: tag in revered commit was wrong, since syzbot
reported different leak in same function.

Link: https://lore.kernel.org/netdev/20210928092657.GI2048@kadam/
Acked-by: Yanfei Xu <[email protected]>
Signed-off-by: Pavel Skripkin <[email protected]>
Link: https://lore.kernel.org/r/f12fb1faa4eccf0f355788225335eb4309ff2599.1633024062.git.paskripkin@gmail.com
Signed-off-by: Jakub Kicinski <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

drivers/net/phy/mdio_bus.c

@@ -544,7 +544,6 @@ int __mdiobus_register(struct mii_bus *bus, struct module *owner)
  err = device_register(&bus->dev);
  if (err) {
  pr_err("mii_bus %s failed to register\n", bus->id);
- put_device(&bus->dev);
  return -EINVAL;
  }