From: Xie He xie.he.0141@gmail.com
[ Upstream commit 5acd0cfbfbb5a688da1bfb1a2152b0c855115a35 ]
There are two "netif_running" checks in this driver. One is in "lapbeth_xmit" and the other is in "lapbeth_rcv". They serve to make sure that the LAPB APIs called in these functions are called before "lapb_unregister" is called by the "ndo_stop" function.
However, these "netif_running" checks are unreliable, because it's possible that immediately after "netif_running" returns true, "ndo_stop" is called (which causes "lapb_unregister" to be called).
This patch adds locking to make sure "lapbeth_xmit" and "lapbeth_rcv" can reliably check and ensure the netif is running while doing their work.
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Xie He xie.he.0141@gmail.com Acked-by: Martin Schiller ms@dev.tdt.de Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/net/wan/lapbether.c | 32 +++++++++++++++++++++++++------- 1 file changed, 25 insertions(+), 7 deletions(-)
diff --git a/drivers/net/wan/lapbether.c b/drivers/net/wan/lapbether.c index 666bbacb8cb4..24daa1d0e9c5 100644 --- a/drivers/net/wan/lapbether.c +++ b/drivers/net/wan/lapbether.c @@ -56,6 +56,8 @@ struct lapbethdev { struct list_head node; struct net_device *ethdev; /* link to ethernet device */ struct net_device *axdev; /* lapbeth device (lapb#) */ + bool up; + spinlock_t up_lock; /* Protects "up" */ };
static LIST_HEAD(lapbeth_devices); @@ -103,8 +105,9 @@ static int lapbeth_rcv(struct sk_buff *skb, struct net_device *dev, struct packe rcu_read_lock(); lapbeth = lapbeth_get_x25_dev(dev); if (!lapbeth) - goto drop_unlock; - if (!netif_running(lapbeth->axdev)) + goto drop_unlock_rcu; + spin_lock_bh(&lapbeth->up_lock); + if (!lapbeth->up) goto drop_unlock;
len = skb->data[0] + skb->data[1] * 256; @@ -119,11 +122,14 @@ static int lapbeth_rcv(struct sk_buff *skb, struct net_device *dev, struct packe goto drop_unlock; } out: + spin_unlock_bh(&lapbeth->up_lock); rcu_read_unlock(); return 0; drop_unlock: kfree_skb(skb); goto out; +drop_unlock_rcu: + rcu_read_unlock(); drop: kfree_skb(skb); return 0; @@ -151,13 +157,11 @@ static int lapbeth_data_indication(struct net_device *dev, struct sk_buff *skb) static netdev_tx_t lapbeth_xmit(struct sk_buff *skb, struct net_device *dev) { + struct lapbethdev *lapbeth = netdev_priv(dev); int err;
- /* - * Just to be *really* sure not to send anything if the interface - * is down, the ethernet device may have gone. - */ - if (!netif_running(dev)) + spin_lock_bh(&lapbeth->up_lock); + if (!lapbeth->up) goto drop;
/* There should be a pseudo header of 1 byte added by upper layers. @@ -188,6 +192,7 @@ static netdev_tx_t lapbeth_xmit(struct sk_buff *skb, goto drop; } out: + spin_unlock_bh(&lapbeth->up_lock); return NETDEV_TX_OK; drop: kfree_skb(skb); @@ -279,6 +284,7 @@ static const struct lapb_register_struct lapbeth_callbacks = { */ static int lapbeth_open(struct net_device *dev) { + struct lapbethdev *lapbeth = netdev_priv(dev); int err;
if ((err = lapb_register(dev, &lapbeth_callbacks)) != LAPB_OK) { @@ -286,13 +292,22 @@ static int lapbeth_open(struct net_device *dev) return -ENODEV; }
+ spin_lock_bh(&lapbeth->up_lock); + lapbeth->up = true; + spin_unlock_bh(&lapbeth->up_lock); + return 0; }
static int lapbeth_close(struct net_device *dev) { + struct lapbethdev *lapbeth = netdev_priv(dev); int err;
+ spin_lock_bh(&lapbeth->up_lock); + lapbeth->up = false; + spin_unlock_bh(&lapbeth->up_lock); + if ((err = lapb_unregister(dev)) != LAPB_OK) pr_err("lapb_unregister error: %d\n", err);
@@ -350,6 +365,9 @@ static int lapbeth_new_device(struct net_device *dev) dev_hold(dev); lapbeth->ethdev = dev;
+ lapbeth->up = false; + spin_lock_init(&lapbeth->up_lock); + rc = -EIO; if (register_netdevice(ndev)) goto fail;