Description
In the Linux kernel, the following vulnerability has been resolved: net: dsa: seville: 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 Seville VSC9959 switch is a platform 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 seville 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 seville driver has a code structure that could accommodate both the mdiobus_unregister and mdiobus_free calls, but it has an external dependency upon mscc_miim_setup() from mdio-mscc-miim.c, which calls devm_mdiobus_alloc_size() on its behalf. So rather than restructuring that, and exporting yet one more symbol mscc_miim_teardown(), let's work with devres and replace of_mdiobus_register with the devres variant. When we use all-devres, we can ensure that devres doesn't free a still-registered bus (it either runs both callbacks, or none).
Affected products
Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.
Linux Linux
Default version status: unaffected
ac3a68d56651c3dad2c12c7afce065fe15267f44 to < 1d13e7221035947c62800c9d3d99b4ed570e27e7affectedac3a68d56651c3dad2c12c7afce065fe15267f44 to < 0e816362d823cd46c666e64d8bffe329ee22f4ccaffectedac3a68d56651c3dad2c12c7afce065fe15267f44 to < bd488afc3b39e045ba71aab472233f2a78726e7baffected
Linux Linux
Default version status: affected
5.9affected0 to < 5.9unaffected5.15.27 to ≤ 5.15.*unaffected5.16.10 to ≤ 5.16.*unaffected5.17 to ≤ *unaffected