ethtool: fix reference leak in some *_SET handlers

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: a53f3d41 ("ethtool: set link settings with LINKINFO_SET request")
Fixes: bfbcfe20 ("ethtool: set link modes related data with LINKMODES_SET request")
Fixes: e54d04e3 ("ethtool: set message mask with DEBUG_SET request")
Fixes: 8d425b19 ("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>

net/ethtool/debug.c

@@ -107,8 +107,9 @@ int ethnl_set_debug(struct sk_buff *skb, struct genl_info *info)
 	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);
@@ -129,6 +130,7 @@ int ethnl_set_debug(struct sk_buff *skb, struct genl_info *info)
 	ethnl_ops_complete(dev);
 out_rtnl:
 	rtnl_unlock();
+out_dev:
 	dev_put(dev);
 	return ret;
 }

net/ethtool/linkinfo.c

@@ -126,9 +126,10 @@ int ethnl_set_linkinfo(struct sk_buff *skb, struct genl_info *info)
 	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);
@@ -162,6 +163,7 @@ int ethnl_set_linkinfo(struct sk_buff *skb, struct genl_info *info)
 	ethnl_ops_complete(dev);
 out_rtnl:
 	rtnl_unlock();
+out_dev:
 	dev_put(dev);
 	return ret;
 }

net/ethtool/linkmodes.c

@@ -338,9 +338,10 @@ int ethnl_set_linkmodes(struct sk_buff *skb, struct genl_info *info)
 	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);
@@ -370,6 +371,7 @@ int ethnl_set_linkmodes(struct sk_buff *skb, struct genl_info *info)
 	ethnl_ops_complete(dev);
 out_rtnl:
 	rtnl_unlock();
+out_dev:
 	dev_put(dev);
 	return ret;
 }

net/ethtool/wol.c

@@ -128,8 +128,9 @@ int ethnl_set_wol(struct sk_buff *skb, struct genl_info *info)
 	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);
@@ -172,6 +173,7 @@ int ethnl_set_wol(struct sk_buff *skb, struct genl_info *info)
 	ethnl_ops_complete(dev);
 out_rtnl:
 	rtnl_unlock();
+out_dev:
 	dev_put(dev);
 	return ret;
 }