CVE-2024-40975

Published Jul 12, 2024

Last updated 8 months ago

Overview

Description
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.
Source
416baaa9-dc9f-4396-8d5f-8c081fb06d67
NVD status
Analyzed
Products
linux_kernel

Risk scores

CVSS 3.1

Type
Primary
Base score
5.5
Impact score
3.6
Exploitability score
1.8
Vector string
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Severity
MEDIUM

Weaknesses

nvd@nist.gov
NVD-CWE-noinfo

Social media

Hype score
Not currently trending

Configurations

  1. In the Linux kernel, the following vulnerability has been resolved: coresight: tmc-etr: Fix race condition between sysfs and perf mode When trying to run perf and sysfs mode simultaneously, the WARN_ON() in tmc_etr_enable_hw() is triggered sometimes: WARNING: CPU: 42 PID: 3911571 at drivers/hwtracing/coresight/coresight-tmc-etr.c:1060 tmc_etr_enable_hw+0xc0/0xd8 [coresight_tmc] [..snip..] Call trace: tmc_etr_enable_hw+0xc0/0xd8 [coresight_tmc] (P) tmc_enable_etr_sink+0x11c/0x250 [coresight_tmc] (L) tmc_enable_etr_sink+0x11c/0x250 [coresight_tmc] coresight_enable_path+0x1c8/0x218 [coresight] coresight_enable_sysfs+0xa4/0x228 [coresight] enable_source_store+0x58/0xa8 [coresight] dev_attr_store+0x20/0x40 sysfs_kf_write+0x4c/0x68 kernfs_fop_write_iter+0x120/0x1b8 vfs_write+0x2c8/0x388 ksys_write+0x74/0x108 __arm64_sys_write+0x24/0x38 el0_svc_common.constprop.0+0x64/0x148 do_el0_svc+0x24/0x38 el0_svc+0x3c/0x130 el0t_64_sync_handler+0xc8/0xd0 el0t_64_sync+0x1ac/0x1b0 ---[ end trace 0000000000000000 ]--- Since the enablement of sysfs mode is separeted into two critical regions, one for sysfs buffer allocation and another for hardware enablement, it's possible to race with the perf mode. Fix this by double check whether the perf mode's been used before enabling the hardware in sysfs mode. mode: [sysfs mode] [perf mode] tmc_etr_get_sysfs_buffer() spin_lock(&drvdata->spinlock) [sysfs buffer allocation] spin_unlock(&drvdata->spinlock) spin_lock(&drvdata->spinlock) tmc_etr_enable_hw() drvdata->etr_buf = etr_perf->etr_buf spin_unlock(&drvdata->spinlock) spin_lock(&drvdata->spinlock) tmc_etr_enable_hw() WARN_ON(drvdata->etr_buf) // WARN sicne etr_buf initialized at the perf side spin_unlock(&drvdata->spinlock) With this fix, we retain the check for CS_MODE_PERF in get_etr_sysfs_buf. This ensures we verify whether the perf mode's already running before we actually allocate the buffer. Then we can save the time of allocating/freeing the sysfs buffer if race with the perf mode.CVE-2026-46272