CVE-2022-49681 is a vulnerability identified in the Linux kernel specifically related to the Xtensa architecture's FPGA (Field Programmable Gate Array) support code. The issue arises in the machine_setup() function where the function of_find_compatible_node() returns a device tree node pointer with its reference count incremented. However, the code fails to properly decrement this reference count by calling of_node_put() when the node pointer is no longer needed. This results in a reference count leak, which is a form of resource leak where kernel memory associated with the device tree node is not released properly. Over time, this can lead to increased memory consumption within the kernel, potentially causing resource exhaustion. The vulnerability is rooted in improper reference counting management, a common programming error in kernel development that can degrade system stability. While this flaw does not directly allow for privilege escalation or arbitrary code execution, the resource leak could be exploited in scenarios where an attacker can repeatedly trigger the vulnerable code path, leading to denial of service (DoS) conditions due to kernel memory exhaustion. The affected versions are identified by specific commit hashes, indicating that this issue is present in certain Linux kernel builds prior to the patch. No known exploits are reported in the wild, and no CVSS score has been assigned yet. The fix involves ensuring that of_node_put() is called appropriately to decrement the reference count and prevent the leak.

For European organizations, the primary impact of CVE-2022-49681 lies in potential system stability and availability issues rather than direct compromise of confidentiality or integrity. Systems running Linux kernels with Xtensa FPGA support that are unpatched may experience gradual memory leaks leading to kernel resource exhaustion. This can cause system slowdowns, crashes, or reboots, impacting critical infrastructure, embedded devices, or industrial control systems that rely on stable Linux kernel operation. Organizations in sectors such as telecommunications, manufacturing, and automotive—where Xtensa-based FPGA devices may be deployed—could face operational disruptions. Although exploitation requires repeated triggering of the vulnerable code path, the lack of authentication barriers in some embedded environments could increase risk. Since no known exploits exist, the threat is currently theoretical but should be addressed proactively to maintain system reliability and prevent denial of service scenarios that could affect service availability and operational continuity.

To mitigate CVE-2022-49681, European organizations should: 1) Identify and inventory Linux systems using the Xtensa architecture with FPGA support, particularly embedded and industrial devices. 2) Apply the official Linux kernel patches that fix the reference count leak as soon as they become available from trusted sources or kernel maintainers. 3) For systems where immediate patching is not feasible, implement monitoring of kernel memory usage and system logs to detect abnormal resource consumption indicative of the leak. 4) Limit access to vulnerable systems to trusted users and networks to reduce the risk of repeated triggering of the vulnerable code path. 5) Engage with device and hardware vendors to confirm firmware and kernel versions and request updates if necessary. 6) Incorporate this vulnerability into vulnerability management and patching cycles, ensuring that embedded and specialized Linux systems are not overlooked. 7) Consider deploying kernel hardening and resource limiting mechanisms where applicable to reduce the impact of potential leaks.