CVE-2024-40975

2024-07-1213:15:19

Linux

web.nvd.nist.gov

linux kernel

x86-android-tablets

vulnerability

resolved

platform/x86

regulator subsystem

lenovo yoga tablet 2 series

bq24190 charger chip

5v boost converter

usb devices

micro usb port

platform_device

i2c_clients

lc824206xa

extcon driver

AI Score

6.6

Confidence

Low

EPSS

Percentile

9.3%

JSON

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-client must be registered first, because that creates
the regulator with the lc824206xa listed as its consumer. If the regulator
has not been registered yet the lc824206xa driver will end up getting
a dummy regulator.

Since in this case both the regulator provider and consumer are I2C
devices, the only way to ensure that the consumer is unregistered first
is to unregister the I2C devices in reverse order of in which they were
created.

For consistency and to avoid similar problems in the future change
x86_android_tablet_remove() to unregister all device types in reverse
order.

Affected configurations

Vulners

Node

linuxlinux_kernelRange6.9.0–6.9.7

linuxlinux_kernelRange6.10.0≥

VendorProductVersionCPE
linuxlinux_kernel*cpe:2.3:a:linux:linux_kernel:*:*:*:*:*:*:*:*

Vendor	Product	Version	CPE
linux	linux_kernel	*	cpe:2.3:a:linux:linux_kernel::::::::

CNA Affected

[
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "unaffected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "drivers/platform/x86/x86-android-tablets/core.c"
    ],
    "versions": [
      {
        "version": "1da177e4c3f4",
        "lessThan": "f0c982853d66",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "1da177e4c3f4",
        "lessThan": "3de0f2627ef8",
        "status": "affected",
        "versionType": "git"
      }
    ]
  },
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "affected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "drivers/platform/x86/x86-android-tablets/core.c"
    ],
    "versions": [
      {
        "version": "6.9.7",
        "lessThanOrEqual": "6.9.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.10",
        "lessThanOrEqual": "*",
        "status": "unaffected",
        "versionType": "original_commit_for_fix"
      }
    ]
  }
]