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

net: dsa: ar9331: register the mdiobus under devres

As explained in commits:
74b6d7d13307 ("net: dsa: realtek: register the MDIO bus under devres")
5135e96a3dd2 ("net: dsa: don't allocate the slave_mii_bus using devres")

mdiobus_free() will panic when called from devm_mdiobus_free() <-
devres_release_all() <- __device_release_driver(), and that mdiobus was
not previously unregistered.

The ar9331 is an MDIO device, so the initial set of constraints that I
thought would cause this (I2C or SPI buses which call ->remove on
->shutdown) do not apply. But there is one more which applies here.

If the DSA master itself is on a bus that calls ->remove from ->shutdown
(like dpaa2-eth, which is on the fsl-mc bus), there is a device link
between the switch and the DSA master, and device_links_unbind_consumers()
will unbind the ar9331 switch driver on shutdown.

So the same treatment must be applied to all DSA switch drivers, which
is: either use devres for both the mdiobus allocation and registration,
or don't use devres at all.

The ar9331 driver doesn't have a complex code structure for mdiobus
removal, so just replace of_mdiobus_register with the devres variant in
order to be all-devres and ensure that we don't free a still-registered
bus.

kernel.org https://git.kernel.org/stable/c/475ce5dcf2d88fd4f3c213a0ac944e3e40702970 [No types assigned]

kernel.org https://git.kernel.org/stable/c/50facd86e9fbc4b93fe02e5fe05776047f45dbfb [No types assigned]

kernel.org https://git.kernel.org/stable/c/aae1c6a1d3d696fc33b609fb12fe744a556d1dc5 [No types assigned]

kernel.org https://git.kernel.org/stable/c/f1842a8cb71de4d7eb75a86f76e88c7ee739218c [No types assigned]