| From bippy-5f407fcff5a0 Mon Sep 17 00:00:00 2001 |
| From: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| To: <linux-cve-announce@vger.kernel.org> |
| Reply-to: <cve@kernel.org>, <linux-kernel@vger.kernel.org> |
| Subject: CVE-2024-40975: platform/x86: x86-android-tablets: Unregister devices in reverse order |
| |
| 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. |
| |
| The Linux kernel CVE team has assigned CVE-2024-40975 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 5.17 with commit 55fa3c9665bfcf32b21af8ecdeb48d5c5177d8d7 and fixed in 6.6.64 with commit 36ff963c133a25ed1166a25c3ba8b357ea010fda |
| Issue introduced in 5.17 with commit 55fa3c9665bfcf32b21af8ecdeb48d5c5177d8d7 and fixed in 6.9.7 with commit f0c982853d665597d17e4995ff479fbbf79a9cf6 |
| Issue introduced in 5.17 with commit 55fa3c9665bfcf32b21af8ecdeb48d5c5177d8d7 and fixed in 6.10 with commit 3de0f2627ef849735f155c1818247f58404dddfe |
| |
| Please see https://www.kernel.org for a full list of currently supported |
| kernel versions by the kernel community. |
| |
| Unaffected versions might change over time as fixes are backported to |
| older supported kernel versions. The official CVE entry at |
| https://cve.org/CVERecord/?id=CVE-2024-40975 |
| will be updated if fixes are backported, please check that for the most |
| up to date information about this issue. |
| |
| |
| Affected files |
| ============== |
| |
| The file(s) affected by this issue are: |
| drivers/platform/x86/x86-android-tablets/core.c |
| |
| |
| Mitigation |
| ========== |
| |
| The Linux kernel CVE team recommends that you update to the latest |
| stable kernel version for this, and many other bugfixes. Individual |
| changes are never tested alone, but rather are part of a larger kernel |
| release. Cherry-picking individual commits is not recommended or |
| supported by the Linux kernel community at all. If however, updating to |
| the latest release is impossible, the individual changes to resolve this |
| issue can be found at these commits: |
| https://git.kernel.org/stable/c/36ff963c133a25ed1166a25c3ba8b357ea010fda |
| https://git.kernel.org/stable/c/f0c982853d665597d17e4995ff479fbbf79a9cf6 |
| https://git.kernel.org/stable/c/3de0f2627ef849735f155c1818247f58404dddfe |
