linux-kernel - [PATCH 3.18 29/92] sh_eth: Fix ethtool operation crash when net device is down

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Message-Id: <20170809202156.680315553@linuxfoundation.org>
Date:   Wed,  9 Aug 2017 13:36:57 -0700
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Ben Hutchings <ben.hutchings@...ethink.co.uk>,
        "David S. Miller" <davem@...emloft.net>,
        Amit Pundir <amit.pundir@...aro.org>
Subject: [PATCH 3.18 29/92] sh_eth: Fix ethtool operation crash when net device is down

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

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

From: Ben Hutchings <ben.hutchings@...ethink.co.uk>

commit 4f9dce230b32eec45cec8c28cae61efdfa2f7d57 upstream.

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>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Amit Pundir <amit.pundir@...aro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/net/ethernet/renesas/sh_eth.c |   10 ++++++++++
 1 file changed, 10 insertions(+)

--- a/drivers/net/ethernet/renesas/sh_eth.c
+++ b/drivers/net/ethernet/renesas/sh_eth.c
@@ -1832,6 +1832,9 @@ static int sh_eth_get_settings(struct ne
 	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);
@@ -1846,6 +1849,9 @@ static int sh_eth_set_settings(struct ne
 	unsigned long flags;
 	int ret;
 
+	if (!mdp->phydev)
+		return -ENODEV;
+
 	spin_lock_irqsave(&mdp->lock, flags);
 
 	/* disable tx and rx */
@@ -1880,6 +1886,9 @@ static int sh_eth_nway_reset(struct net_
 	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);
@@ -2189,6 +2198,7 @@ static int sh_eth_close(struct net_devic
 	if (mdp->phydev) {
 		phy_stop(mdp->phydev);
 		phy_disconnect(mdp->phydev);
+		mdp->phydev = NULL;
 	}
 
 	free_irq(ndev->irq, ndev);