Linux Kernel ACPI EC Custom Query Handler Removal Oops Fix Vulnerability

A vulnerability in the Linux kernel's ACPI EC component can lead to a kernel oops error when custom query handlers are removed. If the module containing the callback function is unloaded, the handler may still be referenced in the EC query workqueue, causing the error. This issue has been observed on an Acer Travelmate 4002WLMi.

Impact

The vulnerability can cause a kernel oops, which is a type of error that can lead to a system crash or instability.

Reproduction

The vulnerability can be reproduced by removing a custom query handler from the ACPI EC component while the handler is still being used in the EC query workqueue. This can be done by unloading the module that contains the callback function before the workqueue has finished processing, which will result in a kernel oops error.

Remediation

The vulnerability has been addressed by modifying the ACPI EC query handler removal process to flush the EC query workqueue before the handler is removed. This change prevents the workqueue from referencing an unloaded module, thereby avoiding the kernel oops error.