CVE-2021-47054 is a vulnerability identified in the Linux kernel, specifically within the Qualcomm (qcom) bus driver subsystem. The issue arises from improper handling of reference counts for child nodes in the device tree during iteration with the macro for_each_available_child_of_node(). Normally, this macro automatically increments and decrements the reference count of child nodes to manage their lifecycle correctly. However, if the loop processing these child nodes is prematurely exited (e.g., via a break statement), the reference count decrement is not performed manually, leading to a potential reference count leak. This leak can cause resource mismanagement in the kernel, potentially leading to memory leaks or use-after-free conditions if the reference counts become inconsistent. The fix involves ensuring that the child node's reference count is decremented before any early return or break from the loop, thus maintaining proper reference counting and preventing resource leaks. Although this vulnerability does not have any known exploits in the wild to date, it affects the Linux kernel versions containing the vulnerable Qualcomm bus driver code, which is widely used in various Linux distributions and embedded systems. The vulnerability was published on February 29, 2024, and is categorized as a kernel-level vulnerability affecting device tree node management in the Qualcomm bus driver.

For European organizations, the impact of CVE-2021-47054 depends largely on the deployment of Linux systems utilizing Qualcomm hardware and the specific kernel versions affected. This vulnerability could lead to kernel instability or denial of service due to resource leaks, which may degrade system availability. In critical infrastructure sectors such as telecommunications, industrial control systems, or embedded devices running Linux on Qualcomm chipsets, this could disrupt operations or cause system crashes. While there is no direct indication that this vulnerability allows privilege escalation or remote code execution, the kernel instability could be leveraged as part of a broader attack chain. Organizations relying on Linux-based network equipment, IoT devices, or mobile infrastructure that incorporate Qualcomm components are at higher risk. The absence of known exploits reduces immediate risk, but unpatched systems remain vulnerable to potential future exploitation. Additionally, the vulnerability could complicate incident response and forensic analysis due to kernel resource mismanagement.

European organizations should prioritize patching Linux kernel versions that include the Qualcomm bus driver to incorporate the fix for CVE-2021-47054. Specifically, kernel updates that address the reference count leak should be applied promptly. For embedded or specialized devices where kernel updates are less frequent, organizations should coordinate with hardware vendors or device manufacturers to obtain patched firmware or kernel versions. Additionally, organizations should audit their Linux systems to identify those running Qualcomm hardware and verify kernel versions. Implementing kernel integrity monitoring and enhanced logging can help detect abnormal kernel behavior indicative of resource leaks or instability. In environments where patching is delayed, applying strict access controls and network segmentation can reduce the attack surface and limit potential impact. Finally, monitoring vendor advisories and threat intelligence feeds for any emerging exploit activity related to this vulnerability is recommended.