From 3c9ef511b9fa128a4c62e3aa0aac4c6b190f0d55 Mon Sep 17 00:00:00 2001 From: Di Zhu Date: Tue, 22 Jun 2021 11:09:29 +0800 Subject: [PATCH] bonding: avoid adding slave device with IFF_MASTER flag The following steps will definitely cause the kernel to crash: ip link add vrf1 type vrf table 1 modprobe bonding.ko max_bonds=1 echo "+vrf1" >/sys/class/net/bond0/bonding/slaves rmmod bonding The root cause is that: When the VRF is added to the slave device, it will fail, and some cleaning work will be done. because VRF device has IFF_MASTER flag, cleanup process will not clear the IFF_BONDING flag. Then, when we unload the bonding module, unregister_netdevice_notifier() will treat the VRF device as a bond master device and treat netdev_priv() as struct bonding{} which actually is struct net_vrf{}. By analyzing the processing logic of bond_enslave(), it seems that it is not allowed to add the slave device with the IFF_MASTER flag, so we need to add a code check for this situation. Signed-off-by: Di Zhu Signed-off-by: David S. Miller --- drivers/net/bonding/bond_main.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c index c5a646d06102..16840c9bc00d 100644 --- a/drivers/net/bonding/bond_main.c +++ b/drivers/net/bonding/bond_main.c @@ -1601,6 +1601,12 @@ int bond_enslave(struct net_device *bond_dev, struct net_device *slave_dev, int link_reporting; int res = 0, i; + if (slave_dev->flags & IFF_MASTER) { + netdev_err(bond_dev, + "Error: Device with IFF_MASTER cannot be enslaved\n"); + return -EPERM; + } + if (!bond->params.use_carrier && slave_dev->ethtool_ops->get_link == NULL && slave_ops->ndo_do_ioctl == NULL) {