CVE-2021-47490 is a vulnerability identified in the Linux kernel's Direct Rendering Manager (DRM) subsystem, specifically within the Translation Table Maps (TTM) memory management component. The issue relates to a memory leak in the function ttm_transfered_destroy, which is responsible for cleaning up resources associated with transferred TTM objects. The vulnerability arises because the cleanup process fails to properly handle 'ghost' objects—objects that have been logically deleted but still have lingering fence references. Fences are synchronization primitives used to manage access to shared resources in graphics memory. The failure to clean up these fences for ghost objects results in a memory leak, which over time can lead to resource exhaustion. Although this vulnerability does not directly enable code execution or privilege escalation, the memory leak can degrade system stability and performance, particularly on systems with heavy graphics workloads or long uptimes. The issue was addressed by ensuring that fences associated with ghost objects are properly cleaned up during the destruction process. The bug reports linked (https://bugzilla.kernel.org/show_bug.cgi?id=214029 and https://bugzilla.kernel.org/show_bug.cgi?id=214447) provide further technical context and patch details. There are no known exploits in the wild at this time, and no CVSS score has been assigned yet.

For European organizations, the impact of CVE-2021-47490 primarily concerns system reliability and availability rather than direct compromise of confidentiality or integrity. Organizations running Linux-based systems with graphical workloads—such as workstations, servers with GPU acceleration, or embedded devices using DRM—may experience gradual memory consumption increases leading to degraded performance or system crashes if the vulnerability is exploited or triggered over time. This can affect sectors reliant on Linux for critical infrastructure, including telecommunications, finance, research institutions, and public services. While the vulnerability does not enable direct remote code execution or privilege escalation, the resulting denial of service through resource exhaustion could disrupt operations, especially in environments where uptime and stability are critical. The lack of known exploits reduces immediate risk, but unpatched systems remain vulnerable to potential future exploitation or inadvertent triggering of the memory leak.

To mitigate CVE-2021-47490, European organizations should prioritize applying the official Linux kernel patches that address the memory leak in the DRM TTM subsystem. This involves updating to the latest stable kernel versions where the fix is included. Organizations should also implement proactive monitoring of system memory usage, particularly on systems with GPU workloads, to detect abnormal memory growth that could indicate exploitation or triggering of the leak. Employing kernel live patching solutions can reduce downtime during patch deployment. Additionally, restricting access to systems with graphical workloads to trusted users and limiting the installation of unverified kernel modules can reduce the attack surface. For embedded or specialized Linux devices, vendors should be engaged to ensure timely firmware updates incorporating the fix. Finally, maintaining robust backup and recovery procedures will help mitigate potential service disruptions caused by system instability.