CVE-2021-47420 is a vulnerability identified in the Linux kernel, specifically within the Direct Rendering Manager (DRM) subsystem related to AMD's Kernel Fusion Driver (amdkfd). The issue pertains to a memory management flaw where allocated memory for scatter-gather (sg) lists, associated with ttm (Translation Table Maps) objects, is not properly freed. In detail, memory is allocated using kmalloc in the function kfd_mem_dmamap_userptr but is not correspondingly freed in the function kfd_mem_dmaunmap_userptr, leading to a potential memory leak. This leak occurs because the allocated scatter-gather memory (ttm->sg) remains allocated even after it should have been released, which can cause gradual exhaustion of kernel memory resources over time. Although this vulnerability does not directly allow code execution or privilege escalation, the memory leak can degrade system performance and stability, potentially leading to denial of service (DoS) conditions if exploited at scale or on critical systems. The flaw affects Linux kernel versions identified by the commit hash 264fb4d332f5e76743818480e482464437837c52 and was publicly disclosed on May 21, 2024. No known exploits are currently reported in the wild, and no CVSS score has been assigned yet. The vulnerability is addressed by ensuring that the allocated memory is properly freed, thus preventing the leak.

For European organizations, the impact of CVE-2021-47420 primarily revolves around system reliability and availability. Organizations running Linux servers, particularly those utilizing AMD GPUs or accelerators managed by the amdkfd driver (common in high-performance computing, AI workloads, and graphics-intensive applications), may experience gradual degradation of system resources due to memory leaks. This can lead to increased downtime, reduced performance, and potential denial of service if the leak is severe and sustained. Critical infrastructure, research institutions, and enterprises relying on Linux-based systems for compute-intensive tasks could be particularly affected. While the vulnerability does not directly compromise confidentiality or integrity, the availability impact can disrupt business operations and service delivery. Given the widespread use of Linux in European data centers, cloud environments, and embedded systems, the vulnerability warrants prompt attention to avoid operational disruptions.

To mitigate CVE-2021-47420, European organizations should: 1) Apply the latest Linux kernel patches that address this memory leak as soon as they become available, ensuring that the amdkfd driver properly frees allocated memory. 2) Monitor system memory usage on Linux hosts running AMD GPU drivers to detect abnormal memory consumption patterns that may indicate exploitation or the presence of the leak. 3) Implement proactive system resource monitoring and alerting to identify early signs of memory exhaustion. 4) For critical systems, consider scheduling regular reboots or driver reloads as a temporary workaround to clear leaked memory until patches are applied. 5) Maintain an inventory of Linux systems using AMD GPUs or accelerators to prioritize patch deployment. 6) Engage with Linux distribution vendors or kernel maintainers to track patch releases and security advisories related to this vulnerability. 7) Incorporate this vulnerability into vulnerability management and incident response processes to ensure timely detection and remediation.