"value":"In the Linux kernel, the following vulnerability has been resolved:\n\nplatform/x86: x86-android-tablets: Unregister devices in reverse order\n\nNot all subsystems support a device getting removed while there are\nstill consumers of the device with a reference to the device.\n\nOne example of this is the regulator subsystem. If a regulator gets\nunregistered while there are still drivers holding a reference\na WARN() at drivers/regulator/core.c:5829 triggers, e.g.:\n\n WARNING: CPU: 1 PID: 1587 at drivers/regulator/core.c:5829 regulator_unregister\n 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\n RIP: 0010:regulator_unregister\n Call Trace:\n <TASK>\n regulator_unregister\n devres_release_group\n i2c_device_remove\n device_release_driver_internal\n bus_remove_device\n device_del\n device_unregister\n x86_android_tablet_remove\n\nOn the Lenovo Yoga Tablet 2 series the bq24190 charger chip also provides\na 5V boost converter output for powering USB devices connected to the micro\nUSB port, the bq24190-charger driver exports this as a Vbus regulator.\n\nOn the 830 (8\") and 1050 (\"10\") models this regulator is controlled by\na platform_device and x86_android_tablet_remove() removes platform_device-s\nbefore i2c_clients so the consumer gets removed first.\n\nBut on the 1380 (13\") model there is a lc824206xa micro-USB switch\nconnected over I2C and the extcon driver for that controls the regulator.\nThe bq24190 i2c-client *must* be registered first, because that creates\nthe regulator with the lc824206xa listed as its consumer. If the regulator\nhas not been registered yet the lc824206xa driver will end up getting\na dummy regulator.\n\nSince in this case both the regulator provider and consumer are I2C\ndevices, the only way to ensure that the consumer is unregistered first\nis to unregister the I2C devices in reverse order of in which they were\ncreated.\n\nFor consistency and to avoid similar problems in the future change\nx86_android_tablet_remove() to unregister all device types in reverse\norder."
