CVE-2021-47551 is a medium-severity vulnerability in the Linux kernel specifically affecting the AMD Kernel Fusion Driver (amdkfd) component within the Direct Rendering Manager (DRM) subsystem. The flaw arises in environments using Single Root I/O Virtualization (SR-IOV) configurations, which are commonly employed to allow multiple virtual functions to share a single physical PCIe device, improving resource utilization in virtualized systems. The vulnerability is triggered when a reset operation on the AMD ASIC fails to restore the device to a normal operational state. In this failure scenario, the driver incorrectly handles the reset sequence by stopping the CPSCH (Compute Scheduler) without subsequently restarting it, because the expected resume operation does not occur. If a reset is triggered again, the driver attempts to uninitialize components that have already been uninitialized, leading to a kernel panic. This kernel panic results in a denial of service (DoS) condition, causing system instability and potential downtime. The vulnerability is categorized under CWE-770 (Allocation of Resources Without Limits or Throttling), indicating improper handling of resource states during reset operations. The CVSS v3.1 base score is 6.5, reflecting a medium severity with local attack vector, low attack complexity, requiring low privileges and no user interaction, and impacting availability with a scope change. No known exploits are currently reported in the wild, and no patches are linked in the provided data, but the issue has been officially published and acknowledged by the Linux project.

For European organizations, especially those relying on Linux servers with AMD GPUs in virtualized environments using SR-IOV (such as cloud service providers, research institutions, and enterprises with high-performance computing needs), this vulnerability poses a risk of unexpected system crashes and service interruptions. The denial of service caused by kernel panics can disrupt critical workloads, leading to operational downtime and potential financial losses. Organizations running containerized or virtualized workloads that leverage AMD GPU acceleration may experience instability, affecting service availability and reliability. While the vulnerability does not directly lead to data breaches or privilege escalation, the availability impact can indirectly affect business continuity and service level agreements (SLAs). Given the widespread use of Linux in European data centers and the increasing adoption of GPU virtualization for AI, machine learning, and graphics workloads, this vulnerability could affect a broad range of sectors including finance, manufacturing, telecommunications, and public services.

European organizations should prioritize updating their Linux kernels to versions where this vulnerability is patched once official fixes are released. Until patches are available, administrators should consider disabling SR-IOV configurations on AMD GPUs if feasible, or avoid triggering reset operations on affected devices. Monitoring system logs for kernel panics related to amdkfd and DRM subsystems can help detect attempts to exploit this issue. Implementing robust system monitoring and automated recovery mechanisms can reduce downtime impact. Additionally, organizations should review and test their high-availability and failover strategies to ensure resilience against unexpected kernel crashes. For environments where AMD GPU virtualization is critical, engaging with Linux distribution vendors and AMD for timely updates and guidance is recommended. Finally, restricting local access to trusted users and limiting the ability to trigger device resets can reduce the risk of exploitation.