Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Florian Fainelli <f.fainelli@gmail.com>,
        Andrew Lunn <andrew@lunn.ch>,
        "David S. Miller" <davem@davemloft.net>
Subject: [PATCH 4.14 013/166] net: phy: Avoid NPD upon phy_detach() when driver is unbound
Date:   Tue, 29 Sep 2020 12:58:45 +0200
Message-Id: <20200929105935.850984691@linuxfoundation.org>
In-Reply-To: <20200929105935.184737111@linuxfoundation.org>
References: <20200929105935.184737111@linuxfoundation.org>
User-Agent: quilt/0.66
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Precedence: bulk

From: Florian Fainelli <f.fainelli@gmail.com>

[ Upstream commit c2b727df7caa33876e7066bde090f40001b6d643 ]

If we have unbound the PHY driver prior to calling phy_detach() (often
via phy_disconnect()) then we can cause a NULL pointer de-reference
accessing the driver owner member. The steps to reproduce are:

echo unimac-mdio-0:01 > /sys/class/net/eth0/phydev/driver/unbind
ip link set eth0 down

Fixes: cafe8df8b9bc ("net: phy: Fix lack of reference count on PHY driver")
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/net/phy/phy_device.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c
@@ -1121,7 +1121,8 @@ void phy_detach(struct phy_device *phyde
 
 	phy_led_triggers_unregister(phydev);
 
-	module_put(phydev->mdio.dev.driver->owner);
+	if (phydev->mdio.dev.driver)
+		module_put(phydev->mdio.dev.driver->owner);
 
 	/* If the device had no specific driver before (i.e. - it
 	 * was using the generic driver), we unbind the device