This is a note to let you know that I've just added the patch titled phy: mdio: fix memory leak to the 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: phy-mdio-fix-memory-leak.patch and it can be found in the queue-4.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 6534bcad3c341cb839ab24a5256abe72c2733dd4 Author: Pavel Skripkin <paskripkin@xxxxxxxxx> Date: Thu Sep 30 20:50:28 2021 +0300 phy: mdio: fix memory leak [ Upstream commit ca6e11c337daf7925ff8a2aac8e84490a8691905 ] Syzbot reported memory leak in MDIO bus interface, the problem was in wrong state logic. MDIOBUS_ALLOCATED indicates 2 states: 1. Bus is only allocated 2. Bus allocated and __mdiobus_register() fails, but device_register() was called In case of device_register() has been called we should call put_device() to correctly free the memory allocated for this device, but mdiobus_free() calls just kfree(dev) in case of MDIOBUS_ALLOCATED state To avoid this behaviour we need to set bus->state to MDIOBUS_UNREGISTERED _before_ calling device_register(), because put_device() should be called even in case of device_register() failure. Link: https://lore.kernel.org/netdev/YVMRWNDZDUOvQjHL@xxxxxxxxxxxxxxxxxxxxx/ Fixes: 46abc02175b3 ("phylib: give mdio buses a device tree presence") Reported-and-tested-by: syzbot+398e7dc692ddbbb4cfec@xxxxxxxxxxxxxxxxxxxxxxxxx Reviewed-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx> Signed-off-by: Pavel Skripkin <paskripkin@xxxxxxxxx> Link: https://lore.kernel.org/r/eceae1429fbf8fa5c73dd2a0d39d525aa905074d.1633024062.git.paskripkin@xxxxxxxxx Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/drivers/net/phy/mdio_bus.c b/drivers/net/phy/mdio_bus.c index 5ea86fd57ae6..4066fb5a935a 100644 --- a/drivers/net/phy/mdio_bus.c +++ b/drivers/net/phy/mdio_bus.c @@ -264,6 +264,13 @@ int __mdiobus_register(struct mii_bus *bus, struct module *owner) bus->dev.groups = NULL; dev_set_name(&bus->dev, "%s", bus->id); + /* We need to set state to MDIOBUS_UNREGISTERED to correctly release + * the device in mdiobus_free() + * + * State will be updated later in this function in case of success + */ + bus->state = MDIOBUS_UNREGISTERED; + err = device_register(&bus->dev); if (err) { pr_err("mii_bus %s failed to register\n", bus->id);