Subject: [PATCH 01/24] bonding: fix event handling for stacked bonds

From: Sabrina Dubroca <[email-masked]>
Date: Fri, 12 Apr 2019 15:04:10 +0200

[ 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.

Reproducer:
  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 <[email-masked]>
Signed-off-by: David S. Miller <[email-masked]>
---
 drivers/net/bonding/bond_main.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index b2c42cae3081..091b454e83fc 100644
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -3198,8 +3198,12 @@ static int bond_netdev_event(struct notifier_block *this,
 		return NOTIFY_DONE;
 
 	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) {
-- 
2.20.1