linux-kernel - [PATCH net-next v2 01/12] ethtool: fix reference leak in ethnl_set

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Message-Id: <c81ba0369c2182ba2e48d13adf2a2589567a6896.1585316159.git.mkubecek@suse.cz>
Date:   Fri, 27 Mar 2020 15:07:22 +0100 (CET)
From:   Michal Kubecek <mkubecek@...e.cz>
To:     David Miller <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>, netdev@...r.kernel.org
Cc:     Jiri Pirko <jiri@...nulli.us>, Andrew Lunn <andrew@...n.ch>,
        Florian Fainelli <f.fainelli@...il.com>,
        John Linville <linville@...driver.com>,
        Johannes Berg <johannes@...solutions.net>,
        Richard Cochran <richardcochran@...il.com>,
        linux-kernel@...r.kernel.org
Subject: [PATCH net-next v2 01/12] ethtool: fix reference leak in
 ethnl_set_privflags()

Andrew noticed that some handlers for *_SET commands leak a netdev
reference if required ethtool_ops callbacks do not exist. One of them is
ethnl_set_privflags(), a simple reproducer would be e.g.

  ip link add veth1 type veth peer name veth2
  ethtool --set-priv-flags veth1 foo on
  ip link del veth1

Make sure dev_put() is called when ethtool_ops check fails.

Fixes: f265d799596a ("ethtool: set device private flags with PRIVFLAGS_SET request")
Reported-by: Andrew Lunn <andrew@...n.ch>
Signed-off-by: Michal Kubecek <mkubecek@...e.cz>
---
 net/ethtool/privflags.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/net/ethtool/privflags.c b/net/ethtool/privflags.c
index e8f03b33db9b..77447dceb109 100644
--- a/net/ethtool/privflags.c
+++ b/net/ethtool/privflags.c
@@ -175,9 +175,10 @@ int ethnl_set_privflags(struct sk_buff *skb, struct genl_info *info)
 		return ret;
 	dev = req_info.dev;
 	ops = dev->ethtool_ops;
+	ret = -EOPNOTSUPP;
 	if (!ops->get_priv_flags || !ops->set_priv_flags ||
 	    !ops->get_sset_count || !ops->get_strings)
-		return -EOPNOTSUPP;
+		goto out_dev;
 
 	rtnl_lock();
 	ret = ethnl_ops_begin(dev);
@@ -204,6 +205,7 @@ int ethnl_set_privflags(struct sk_buff *skb, struct genl_info *info)
 	ethnl_ops_complete(dev);
 out_rtnl:
 	rtnl_unlock();
+out_dev:
 	dev_put(dev);
 	return ret;
 }
-- 
2.25.1