r6040: Fix kmemleak in probe and remove

In the Linux kernel, the following vulnerability has been resolved:

r6040: Fix kmemleak in probe and remove

There is a memory leaks reported by kmemleak:

unreferenced object 0xffff888116111000 (size 2048):

comm "modprobe", pid 817, jiffies 4294759745 (age 76.502s)

hex dump (first 32 bytes):

00 c4 0a 04 81 88 ff ff 08 10 11 16 81 88 ff ff ................

08 10 11 16 81 88 ff ff 00 00 00 00 00 00 00 00 ................

backtrace:

[<ffffffff815bcd82>] kmalloc_trace+0x22/0x60

[<ffffffff827e20ee>] phy_device_create+0x4e/0x90

[<ffffffff827e6072>] get_phy_device+0xd2/0x220

[<ffffffff827e7844>] mdiobus_scan+0xa4/0x2e0

[<ffffffff827e8be2>] __mdiobus_register+0x482/0x8b0

[<ffffffffa01f5d24>] r6040_init_one+0x714/0xd2c [r6040]

...

The problem occurs in probe process as follows:

r6040_init_one:

mdiobus_register

mdiobus_scan <- alloc and register phy_device,

the reference count of phy_device is 3

r6040_mii_probe

phy_connect <- connect to the first phy_device,

so the reference count of the first

phy_device is 4, others are 3

register_netdev <- fault inject succeeded, goto error handling path

// error handling path

err_out_mdio_unregister:

mdiobus_unregister(lp->mii_bus);

err_out_mdio:

mdiobus_free(lp->mii_bus); <- the reference count of the first

phy_device is 1, it is not released

and other phy_devices are released

// similarly, the remove process also has the same problem

The root cause is traced to the phy_device is not disconnected when

removes one r6040 device in r6040_remove_one() or on error handling path

after r6040_mii probed successfully. In r6040_mii_probe(), a net ethernet

device is connected to the first PHY device of mii_bus, in order to

notify the connected driver when the link status changes, which is the

default behavior of the PHY infrastructure to handle everything.

Therefore the phy_device should be disconnected when removes one r6040

device or on error handling path.

Fix it by adding phy_disconnect() when removes one r6040 device or on

error handling path after r6040_mii probed successfully.