Affected: Linux

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

platform/x86: x86-android-tablets: Unregister devices in reverse order

Not all subsystems support a device getting removed while there are still consumers of the device with a reference to the device.

One example of this is the regulator subsystem. If a regulator gets unregistered while there are still drivers holding a reference a WARN() at drivers/regulator/core.c:5829 triggers, e.g.:

WARNING: CPU: 1 PID: 1587 at drivers/regulator/core.c:5829 regulator_unregister Hardware name: Intel Corp. VALLEYVIEW C0 PLATFORM/BYT-T FFD8, BIOS BLADE_21.X64.0005.R00.1504101516 FFD8_X64_R_2015_04_10_1516 04/10/2015 RIP: 0010:regulator_unregister Call Trace: <TASK> regulator_unregister devres_release_group i2c_device_remove device_release_driver_internal bus_remove_device device_del device_unregister x86_android_tablet_remove

On the Lenovo Yoga Tablet 2 series the bq24190 charger chip also provides a 5V boost converter output for powering USB devices connected to the micro USB port, the bq24190-charger driver exports this as a Vbus regulator.

On the 830 (8") and 1050 ("10") models this regulator is controlled by a platform_device and x86_android_tablet_remove() removes platform_device-s before i2c_clients so the consumer gets removed first.

But on the 1380 (13") model there is a lc824206xa micro-USB switch connected over I2C and the extcon driver for that controls the regulator. The bq24190 i2c-…