Andrew noticed that some handlers for *_SET commands leak a netdev
reference if required ethtool_ops callbacks do not exist. A simple
reproducer would be e.g.
  ip link add veth1 type veth peer name veth2
  ethtool -s veth1 wol g
  ip link del veth1
Make sure dev_put() is called when ethtool_ops check fails.
v2: add Fixes tags
Fixes: a53f3d41e4d3 ("ethtool: set link settings with LINKINFO_SET request")
Fixes: bfbcfe2032e7 ("ethtool: set link modes related data with LINKMODES_SET request")
Fixes: e54d04e3afea ("ethtool: set message mask with DEBUG_SET request")
Fixes: 8d425b19b305 ("ethtool: set wake-on-lan settings with WOL_SET request")
Reported-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Michal Kubecek <mkubecek@suse.cz>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Reviewed-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
        if (ret < 0)
                return ret;
        dev = req_info.dev;
+       ret = -EOPNOTSUPP;
        if (!dev->ethtool_ops->get_msglevel || !dev->ethtool_ops->set_msglevel)
-               return -EOPNOTSUPP;
+               goto out_dev;
 
        rtnl_lock();
        ret = ethnl_ops_begin(dev);
        ethnl_ops_complete(dev);
 out_rtnl:
        rtnl_unlock();
+out_dev:
        dev_put(dev);
        return ret;
 }
 
        if (ret < 0)
                return ret;
        dev = req_info.dev;
+       ret = -EOPNOTSUPP;
        if (!dev->ethtool_ops->get_link_ksettings ||
            !dev->ethtool_ops->set_link_ksettings)
-               return -EOPNOTSUPP;
+               goto out_dev;
 
        rtnl_lock();
        ret = ethnl_ops_begin(dev);
        ethnl_ops_complete(dev);
 out_rtnl:
        rtnl_unlock();
+out_dev:
        dev_put(dev);
        return ret;
 }
 
        if (ret < 0)
                return ret;
        dev = req_info.dev;
+       ret = -EOPNOTSUPP;
        if (!dev->ethtool_ops->get_link_ksettings ||
            !dev->ethtool_ops->set_link_ksettings)
-               return -EOPNOTSUPP;
+               goto out_dev;
 
        rtnl_lock();
        ret = ethnl_ops_begin(dev);
        ethnl_ops_complete(dev);
 out_rtnl:
        rtnl_unlock();
+out_dev:
        dev_put(dev);
        return ret;
 }
 
        if (ret < 0)
                return ret;
        dev = req_info.dev;
+       ret = -EOPNOTSUPP;
        if (!dev->ethtool_ops->get_wol || !dev->ethtool_ops->set_wol)
-               return -EOPNOTSUPP;
+               goto out_dev;
 
        rtnl_lock();
        ret = ethnl_ops_begin(dev);
        ethnl_ops_complete(dev);
 out_rtnl:
        rtnl_unlock();
+out_dev:
        dev_put(dev);
        return ret;
 }