"value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet: dsa: ar9331: register the mdiobus under devres\n\nAs explained in commits:\n74b6d7d13307 (\"net: dsa: realtek: register the MDIO bus under devres\")\n5135e96a3dd2 (\"net: dsa: don't allocate the slave_mii_bus using devres\")\n\nmdiobus_free() will panic when called from devm_mdiobus_free() <-\ndevres_release_all() <- __device_release_driver(), and that mdiobus was\nnot previously unregistered.\n\nThe ar9331 is an MDIO device, so the initial set of constraints that I\nthought would cause this (I2C or SPI buses which call ->remove on\n->shutdown) do not apply. But there is one more which applies here.\n\nIf the DSA master itself is on a bus that calls ->remove from ->shutdown\n(like dpaa2-eth, which is on the fsl-mc bus), there is a device link\nbetween the switch and the DSA master, and device_links_unbind_consumers()\nwill unbind the ar9331 switch driver on shutdown.\n\nSo the same treatment must be applied to all DSA switch drivers, which\nis: either use devres for both the mdiobus allocation and registration,\nor don't use devres at all.\n\nThe ar9331 driver doesn't have a complex code structure for mdiobus\nremoval, so just replace of_mdiobus_register with the devres variant in\norder to be all-devres and ensure that we don't free a still-registered\nbus."
