[PATCH 4.7 027/184] bonding: Fix bonding crash

[Greg Kroah-Hartman]

4.7-stable review patch.  If anyone has any objections, please let me know.

--

From: Mahesh Bandewar 


[ Upstream commit 24b27fc4cdf9e10c5e79e5923b6b7c2c5c95096c ]

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
  

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 
Acked-by: Eric Dumazet 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman 
---
 drivers/net/bonding/bond_main.c |7 ---
 include/linux/netdevice.h   |1 +
 net/core/dev.c  |   16 
 3 files changed, 21 insertions(+), 3 deletions(-)

--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -1341,9 +1341,10 @@ int bond_enslave(struct net_device *bond
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;
}
 
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -3225,6 +3225,7 @@ static inline void napi_free_frags(struc
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);
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -3979,6 +3979,22 @@ sch_handle_ingress(struct sk_buff *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
  * @rx_handler: receive handler to register

[PATCH 4.7 027/184] bonding: Fix bonding crash

[Greg Kroah-Hartman]

4.7-stable review patch.  If anyone has any objections, please let me know.

--

From: Mahesh Bandewar 


[ Upstream commit 24b27fc4cdf9e10c5e79e5923b6b7c2c5c95096c ]

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
  

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 
Acked-by: Eric Dumazet 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman 
---
 drivers/net/bonding/bond_main.c |7 ---
 include/linux/netdevice.h   |1 +
 net/core/dev.c  |   16 
 3 files changed, 21 insertions(+), 3 deletions(-)

--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -1341,9 +1341,10 @@ int bond_enslave(struct net_device *bond
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;
}
 
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -3225,6 +3225,7 @@ static inline void napi_free_frags(struc
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);
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -3979,6 +3979,22 @@ sch_handle_ingress(struct sk_buff *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
  * @rx_handler: receive handler to register