bridge: check iface upper dev when setting master via ioctl

[ Upstream commit e8238fc2bd7b4c3c7554fa2df067e796610212fc ]

When we set a bond slave's master to bridge via ioctl, we only check
the IFF_BRIDGE_PORT flag. Although we will find the slave's real master
at netdev_master_upper_dev_link() later, it already does some settings
and allocates some resources. It would be better to return as early
as possible.

v1 -> v2:
use netdev_master_upper_dev_get() instead of netdev_has_any_upper_dev()
to check if we have a master, because not all upper devs are masters,
e.g. vlan device.

Reported-by: syzbot+de73361ee4971b6e6f75@syzkaller.appspotmail.com
Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
Acked-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/net/bridge/br_if.c b/net/bridge/br_if.c
index ec02f58..3400b1e 100644 (file)
--- a/net/bridge/br_if.c
+++ b/net/bridge/br_if.c
@@ -456,8 +456,8 @@ int br_add_if(struct net_bridge *br, struct net_device *dev)
        if (dev->netdev_ops->ndo_start_xmit == br_dev_xmit)
                return -ELOOP;
 
-       /* Device is already being bridged */
-       if (br_port_exists(dev))
+       /* Device has master upper dev */
+       if (netdev_master_upper_dev_get(dev))
                return -EBUSY;
 
        /* No bridging devices that dislike that (e.g. wireless) */