Commit 2250392d authored Sep 30, 2021 by Pavel Skripkin Committed by Greg Kroah-Hartman Oct 17, 2021

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@shell.armlinux.org.uk/


Fixes: 46abc021 ("phylib: give mdio buses a device tree presence")
Reported-and-tested-by:  <syzbot+398e7dc692ddbbb4cfec@syzkaller.appspotmail.com>
Reviewed-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
Link: https://lore.kernel.org/r/eceae1429fbf8fa5c73dd2a0d39d525aa905074d.1633024062.git.paskripkin@gmail.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

parent 4fd6663e

drivers/net/phy/mdio_bus.c

+7 −0

Original line number	Diff line number	Diff line
		@@ -316,6 +316,13 @@ 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);