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Commit 24b27fc4 authored by Mahesh Bandewar's avatar Mahesh Bandewar Committed by David S. Miller
Browse files

bonding: Fix bonding crash 



Following few steps will crash kernel -

  (a) Create bonding master
      > modprobe bonding miimon=50
  (b) Create macvlan bridge on eth2
      > ip link add link eth2 dev mvl0 address aa:0:0:0:0:01 \
	   type macvlan
  (c) Now try adding eth2 into the bond
      > echo +eth2 > /sys/class/net/bond0/bonding/slaves
      <crash>

Bonding does lots of things before checking if the device enslaved is
busy or not.

In this case when the notifier call-chain sends notifications, the
bond_netdev_event() assumes that the rx_handler /rx_handler_data is
registered while the bond_enslave() hasn't progressed far enough to
register rx_handler for the new slave.

This patch adds a rx_handler check that can be performed right at the
beginning of the enslave code to avoid getting into this situation.

Signed-off-by: default avatarMahesh Bandewar <maheshb@google.com>
Acked-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 312565a0

drivers/net/bonding/bond_main.c

+4 −3
Original line number Original line Diff line number Diff line
@@ -1341,9 +1341,10 @@ int bond_enslave(struct net_device *bond_dev, struct net_device *slave_dev) 
			    slave_dev->name);

			    slave_dev->name);

	}

	}





	/* already enslaved */

	/* already in-use? */

	if (slave_dev->flags & IFF_SLAVE) {

	if (netdev_is_rx_handler_busy(slave_dev)) {

		netdev_dbg(bond_dev, "Error: Device was already enslaved\n");

		netdev_err(bond_dev,

			   "Error: Device is in use and cannot be enslaved\n");

		return -EBUSY;

		return -EBUSY;

	}

	}

include/linux/netdevice.h

+1 −0
Original line number Original line Diff line number Diff line
@@ -3267,6 +3267,7 @@ static inline void napi_free_frags(struct napi_struct *napi) 
	napi->skb = NULL;

	napi->skb = NULL;

}

}





bool netdev_is_rx_handler_busy(struct net_device *dev);

int netdev_rx_handler_register(struct net_device *dev,

int netdev_rx_handler_register(struct net_device *dev,

			       rx_handler_func_t *rx_handler,

			       rx_handler_func_t *rx_handler,

			       void *rx_handler_data);

			       void *rx_handler_data);

net/core/dev.c

+16 −0
Original line number Original line Diff line number Diff line
@@ -3974,6 +3974,22 @@ sch_handle_ingress(struct sk_buff *skb, struct packet_type **pt_prev, int *ret, 
	return skb;

	return skb;

}

}





/**

 *	netdev_is_rx_handler_busy - check if receive handler is registered

 *	@dev: device to check

 *

 *	Check if a receive handler is already registered for a given device.

 *	Return true if there one.

 *

 *	The caller must hold the rtnl_mutex.

 */

bool netdev_is_rx_handler_busy(struct net_device *dev)

{

	ASSERT_RTNL();

	return dev && rtnl_dereference(dev->rx_handler);

}

EXPORT_SYMBOL_GPL(netdev_is_rx_handler_busy);



/**

/**

 *	netdev_rx_handler_register - register receive handler

 *	netdev_rx_handler_register - register receive handler

 *	@dev: device to register a handler for

 *	@dev: device to register a handler for