[PATCH 3.18 090/104] bonding: fix event handling for stacked bonds

From: Greg Kroah-Hartman
Date: Wed Apr 24 2019 - 13:14:53 EST

From: Sabrina Dubroca <sd@xxxxxxxxxxxxxxx>

[ Upstream commit 92480b3977fd3884649d404cbbaf839b70035699 ]

When a bond is enslaved to another bond, bond_netdev_event() only
handles the event as if the bond is a master, and skips treating the
bond as a slave.

This leads to a refcount leak on the slave, since we don't remove the
adjacency to its master and the master holds a reference on the slave.

ip link add bondL type bond
ip link add bondU type bond
ip link set bondL master bondU
ip link del bondL

No "Fixes:" tag, this code is older than git history.

Signed-off-by: Sabrina Dubroca <sd@xxxxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
drivers/net/bonding/bond_main.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)

--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -2958,8 +2958,12 @@ static int bond_netdev_event(struct noti

if (event_dev->flags & IFF_MASTER) {
+ int ret;
netdev_dbg(event_dev, "IFF_MASTER\n");
- return bond_master_netdev_event(event, event_dev);
+ ret = bond_master_netdev_event(event, event_dev);
+ if (ret != NOTIFY_DONE)
+ return ret;

if (event_dev->flags & IFF_SLAVE) {