netdev - [PATCH net 2/2] sh_eth: Fix ethtool operation crash when net device is down

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Message-ID: <1421430685.1222.192.camel@xylophone.i.decadent.org.uk>
Date:	Fri, 16 Jan 2015 17:51:25 +0000
From:	Ben Hutchings <ben.hutchings@...ethink.co.uk>
To:	ct178-internal@...ts.codethink.co.uk,
	"David S. Miller" <davem@...emloft.net>
Cc:	netdev@...r.kernel.org, linux-kernel@...ts.codethink.co.uk,
	Nobuhiro Iwamatsu <nobuhiro.iwamatsu.yj@...esas.com>,
	Mitsuhiro Kimura <mitsuhiro.kimura.kc@...esas.com>,
	Hisashi Nakamura <hisashi.nakamura.ak@...esas.com>,
	Yoshihiro Kaneko <ykaneko0929@...il.com>
Subject: [PATCH net 2/2] 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@...ethink.co.uk>
---
 drivers/net/ethernet/renesas/sh_eth.c |   10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/net/ethernet/renesas/sh_eth.c b/drivers/net/ethernet/renesas/sh_eth.c
index 0c4d5b5..28e3822 100644
--- 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);
-- 
1.7.10.4



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