sh_eth: Fix ethtool operation crash when net device is down

The driver connects and disconnects the PHY device whenever the
net device is brought up and down.  The ethtool get_settings,
set_settings and nway_reset operations will dereference a null
or dangling pointer if called while it is down.

I think it would be preferable to keep the PHY connected, but there
may be good reasons not to.

As an immediate fix for this bug:
- Set the phydev pointer to NULL after disconnecting the PHY
- Change those three operations to return -ENODEV while the PHY is
  not connected

Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/ethernet/renesas/sh_eth.c b/drivers/net/ethernet/renesas/sh_eth.c
index 01dfae4fece03dd57d8b908553ec79c43f28d265..6576243222af74f593419e6e338cdd9387b949af 100644 (file)
--- a/drivers/net/ethernet/renesas/sh_eth.c
+++ b/drivers/net/ethernet/renesas/sh_eth.c
@@ -1827,6 +1827,9 @@ static int sh_eth_get_settings(struct net_device *ndev,
        unsigned long flags;
        int ret;
 
+       if (!mdp->phydev)
+               return -ENODEV;
+
        spin_lock_irqsave(&mdp->lock, flags);
        ret = phy_ethtool_gset(mdp->phydev, ecmd);
        spin_unlock_irqrestore(&mdp->lock, flags);
@@ -1841,6 +1844,9 @@ static int sh_eth_set_settings(struct net_device *ndev,
        unsigned long flags;
        int ret;
 
+       if (!mdp->phydev)
+               return -ENODEV;
+
        spin_lock_irqsave(&mdp->lock, flags);
 
        /* disable tx and rx */
@@ -1875,6 +1881,9 @@ static int sh_eth_nway_reset(struct net_device *ndev)
        unsigned long flags;
        int ret;
 
+       if (!mdp->phydev)
+               return -ENODEV;
+
        spin_lock_irqsave(&mdp->lock, flags);
        ret = phy_start_aneg(mdp->phydev);
        spin_unlock_irqrestore(&mdp->lock, flags);
@@ -2184,6 +2193,7 @@ static int sh_eth_close(struct net_device *ndev)
        if (mdp->phydev) {
                phy_stop(mdp->phydev);
                phy_disconnect(mdp->phydev);
+               mdp->phydev = NULL;
        }
 
        free_irq(ndev->irq, ndev);