linux-kernel - [56/90] smsc9420: prevent BUG() if ethtool is called with interface down

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Date:	Wed, 16 Dec 2009 17:15:07 -0800
From:	Greg KH <gregkh@...e.de>
To:	linux-kernel@...r.kernel.org, stable@...nel.org
Cc:	stable-review@...nel.org, torvalds@...ux-foundation.org,
	akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk,
	Steve Glendinning <steve.glendinning@...c.com>,
	"David S. Miller" <davem@...emloft.net>
Subject: [56/90] smsc9420: prevent BUG() if ethtool is called with interface down

2.6.31-stable review patch.  If anyone has any objections, please let us know.

------------------


From: Steve Glendinning <steve.glendinning@...c.com>

[ Upstream commit 6c53b1b15e222244358d3cbbefd2a13920faa352 ]

This patch fixes a null pointer dereference BUG() if ethtool is used on
an smsc9420 interface while it is down, because the phy_dev is only
allocated while the interface is up.

Signed-off-by: Steve Glendinning <steve.glendinning@...c.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>
---
 drivers/net/smsc9420.c |   14 ++++++++++++++
 1 file changed, 14 insertions(+)

--- a/drivers/net/smsc9420.c
+++ b/drivers/net/smsc9420.c
@@ -252,6 +252,9 @@ static int smsc9420_ethtool_get_settings
 {
 	struct smsc9420_pdata *pd = netdev_priv(dev);
 
+	if (!pd->phy_dev)
+		return -ENODEV;
+
 	cmd->maxtxpkt = 1;
 	cmd->maxrxpkt = 1;
 	return phy_ethtool_gset(pd->phy_dev, cmd);
@@ -262,6 +265,9 @@ static int smsc9420_ethtool_set_settings
 {
 	struct smsc9420_pdata *pd = netdev_priv(dev);
 
+	if (!pd->phy_dev)
+		return -ENODEV;
+
 	return phy_ethtool_sset(pd->phy_dev, cmd);
 }
 
@@ -290,6 +296,10 @@ static void smsc9420_ethtool_set_msgleve
 static int smsc9420_ethtool_nway_reset(struct net_device *netdev)
 {
 	struct smsc9420_pdata *pd = netdev_priv(netdev);
+
+	if (!pd->phy_dev)
+		return -ENODEV;
+
 	return phy_start_aneg(pd->phy_dev);
 }
 
@@ -312,6 +322,10 @@ smsc9420_ethtool_getregs(struct net_devi
 	for (i = 0; i < 0x100; i += (sizeof(u32)))
 		data[j++] = smsc9420_reg_read(pd, i);
 
+	// cannot read phy registers if the net device is down
+	if (!phy_dev)
+		return;
+
 	for (i = 0; i <= 31; i++)
 		data[j++] = smsc9420_mii_read(phy_dev->bus, phy_dev->addr, i);
 }


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