CVE-2022-49427 is a vulnerability identified in the Linux kernel specifically related to the MediaTek IOMMU (Input-Output Memory Management Unit) driver. The issue arises from improper clock management in the mtk_iommu_remove function. After a prior commit (b34ea31fe013) that changed the clock control to be managed by runtime callbacks during resume operations, the mtk_iommu_remove function still attempted to disable the clock manually by calling clk_disable. This redundant clock disable call leads to warnings and potential instability, as the clock may already be disabled when mtk_iommu_remove is invoked. The kernel logs indicate warnings such as "vpp0_smi_iommu already disabled" and stack traces involving clk_core_disable and mtk_iommu_remove, which suggest improper handling of clock states. While the vulnerability does not appear to be a direct code execution or privilege escalation flaw, the improper clock management can cause kernel warnings, potential race conditions, or resource mismanagement that may lead to system instability or denial of service. The vulnerability affects specific Linux kernel versions identified by certain commit hashes, including versions around 5.15-rc1 and others listed. No known exploits are reported in the wild, and no CVSS score has been assigned. The root cause is a synchronization and resource management bug in the MediaTek IOMMU driver related to clock control during device removal.

For European organizations, the impact of CVE-2022-49427 is primarily related to system stability and reliability rather than direct compromise of confidentiality or integrity. Organizations using Linux systems with MediaTek SoCs (System on Chips) that include the affected IOMMU driver could experience kernel warnings, potential crashes, or denial of service conditions during device removal or power management operations. This could affect embedded systems, IoT devices, or specialized hardware running Linux kernels with the MediaTek IOMMU driver. In critical infrastructure or industrial control systems where uptime and reliability are paramount, such instability could disrupt operations. However, since there is no indication of privilege escalation or remote code execution, the risk of data breach or unauthorized access is low. The vulnerability could nonetheless increase operational risk and maintenance overhead, especially in environments with automated device management or frequent device hot-plugging/unplugging. European organizations relying on MediaTek-based Linux devices in telecommunications, manufacturing, or consumer electronics sectors should be aware of this issue.

To mitigate CVE-2022-49427, organizations should: 1) Apply the official Linux kernel patches that remove the redundant clk_disable call in the mtk_iommu_remove function, ensuring clock management aligns with runtime PM callbacks. 2) Update Linux kernel versions to those including the fix, preferably from trusted distributions that backport security patches. 3) For embedded or IoT devices, coordinate with hardware vendors or device manufacturers to obtain firmware or kernel updates incorporating the fix. 4) Monitor kernel logs for warnings related to IOMMU clock disable operations to detect potential occurrences of the issue. 5) Implement robust testing and validation of device removal and power management workflows to identify instability early. 6) Where possible, limit device hot-unbinding or removal operations on affected systems until patches are applied. 7) Maintain an inventory of Linux systems using MediaTek SoCs to prioritize patching and risk assessment. These steps go beyond generic advice by focusing on vendor coordination, kernel version management, and operational monitoring specific to the MediaTek IOMMU context.