[PATCH 4.16 02/55] bridge: check iface upper dev when setting master via ioctl

Greg Kroah-Hartman
2018-05-18T08:14:58Z

From: Hangbin Liu <liuhangbin@gmail.com>

[ 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>
---
net/bridge/br_if.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

--- a/net/bridge/br_if.c
+++ b/net/bridge/br_if.c
@@ -509,8 +509,8 @@ int br_add_if(struct net_bridge *br, str
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) */