4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Gao Feng <gfree.w...@vip.163.com>


[ Upstream commit d02fd6e7d2933ede6478a15f9e4ce8a93845824e ]

Because the macvlan_uninit would free the macvlan port, so there is one
double free case in macvlan_common_newlink. When the macvlan port is just
created, then register_netdevice or netdev_upper_dev_link failed and they
would invoke macvlan_uninit. Then it would reach the macvlan_port_destroy
which triggers the double free.

Signed-off-by: Gao Feng <gfree.w...@vip.163.com>
Signed-off-by: David S. Miller <da...@davemloft.net>
Signed-off-by: Sasha Levin <alexander.le...@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
 drivers/net/macvlan.c |    7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

--- a/drivers/net/macvlan.c
+++ b/drivers/net/macvlan.c
@@ -1377,9 +1377,14 @@ int macvlan_common_newlink(struct net *s
        return 0;
 
 unregister_netdev:
+       /* macvlan_uninit would free the macvlan port */
        unregister_netdevice(dev);
+       return err;
 destroy_macvlan_port:
-       if (create)
+       /* the macvlan port may be freed by macvlan_uninit when fail to 
register.
+        * so we destroy the macvlan port only when it's valid.
+        */
+       if (create && macvlan_port_get_rtnl(dev))
                macvlan_port_destroy(port->dev);
        return err;
 }


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