netdev - [PATCH net-next] net: phy: Ensure scheduled work is cancelled during removal

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Message-Id: <1559330150-30099-2-git-send-email-hancock@sedsystems.ca>
Date:   Fri, 31 May 2019 13:15:50 -0600
From:   Robert Hancock <hancock@...systems.ca>
To:     netdev@...r.kernel.org
Cc:     Robert Hancock <hancock@...systems.ca>
Subject: [PATCH net-next] net: phy: Ensure scheduled work is cancelled during removal

It is possible that scheduled work started by the PHY driver is still
outstanding when phy_device_remove is called if the PHY was initially
started but never connected, and therefore phy_disconnect is never
called. phy_stop does not guarantee that the scheduled work is stopped
because it is called under rtnl_lock. This can cause an oops due to
use-after-free if the delayed work fires after freeing the PHY device.

Ensure that the state_queue work is cancelled in both phy_device_remove
and phy_remove paths.

Signed-off-by: Robert Hancock <hancock@...systems.ca>
---
 drivers/net/phy/phy_device.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
index 2c879ba..1c90b33 100644
--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c
@@ -877,6 +877,8 @@ int phy_device_register(struct phy_device *phydev)
  */
 void phy_device_remove(struct phy_device *phydev)
 {
+	cancel_delayed_work_sync(&phydev->state_queue);
+
 	device_del(&phydev->mdio.dev);

 	/* Assert the reset signal */
-- 
1.8.3.1