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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: Mahesh Bandewar <maheshb@google.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Mahesh Bandewar 2016-09-01 22:18:34 -07:00 committed by David S. Miller
parent 312565a0c3
commit 24b27fc4cd
3 changed files with 21 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
drivers/net/bonding/bond_main.c
View File

@ -1341,9 +1341,10 @@ int bond_enslave(struct net_device *bond_dev, struct net_device *slave_dev)
slave_dev->name);
}
/* already enslaved */
if (slave_dev->flags & IFF_SLAVE) {
netdev_dbg(bond_dev, "Error: Device was already enslaved\n");
/* already in-use? */
if (netdev_is_rx_handler_busy(slave_dev)) {
netdev_err(bond_dev,
"Error: Device is in use and cannot be enslaved\n");
return -EBUSY;
}

1
include/linux/netdevice.h
View File

@ -3267,6 +3267,7 @@ static inline void napi_free_frags(struct napi_struct *napi)
napi->skb = NULL;
}
bool netdev_is_rx_handler_busy(struct net_device *dev);
int netdev_rx_handler_register(struct net_device *dev,
rx_handler_func_t *rx_handler,
void *rx_handler_data);

16
net/core/dev.c
View File

@ -3974,6 +3974,22 @@ sch_handle_ingress(struct sk_buff *skb, struct packet_type **pt_prev, int *ret,
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
* @dev: device to register a handler for