CVE-2021-47489 is a vulnerability identified in the Linux kernel specifically within the AMDGPU driver component, which handles graphics processing for AMD GPUs. The issue pertains to out-of-bounds write operations occurring in the debugfs interface of the amdgpu_dm_debugfs.c file. This vulnerability is a continuation of a previously fixed issue (CVE-2021-42327) where out-of-bounds writes were addressed in the drm/amdgpu driver. However, further investigation revealed additional similar out-of-bounds write flaws in the debugfs code that were not covered by the initial patch. The vulnerability arises from improper bounds checking when writing to debugfs entries related to the AMDGPU Direct Rendering Manager (DRM) driver, potentially allowing a local attacker with access to debugfs to write beyond allocated memory buffers. This could lead to memory corruption, which may result in system instability, kernel crashes (denial of service), or potentially privilege escalation if exploited to execute arbitrary code within the kernel context. The fix involved extending the bounds checking and correcting the write operations in the affected debugfs functions, including the dp_max_bpc_write function. The vulnerability affects specific Linux kernel versions identified by commit hashes, and the patch was committed in October 2021. No known exploits are reported in the wild as of the publication date. The vulnerability requires local access to the system and interaction with debugfs, which is typically mounted and accessible only to privileged users or processes. Therefore, exploitation would likely require local user privileges or a compromised local account.

For European organizations, the impact of CVE-2021-47489 depends largely on the deployment of Linux systems using AMD GPUs with the affected kernel versions. Organizations running Linux servers, workstations, or embedded systems with AMDGPU drivers and debugfs enabled could be at risk. Successful exploitation could lead to denial of service through kernel crashes or potentially privilege escalation, allowing attackers to gain higher system privileges. This could compromise the confidentiality, integrity, and availability of critical systems. Sectors with high reliance on Linux infrastructure, such as telecommunications, finance, research institutions, and government agencies, could face operational disruptions or data breaches if exploited. However, the requirement for local access and interaction with debugfs limits the attack surface primarily to insider threats or attackers who have already gained some level of system access. The absence of known exploits in the wild reduces immediate risk but does not eliminate the potential for future exploitation. Organizations using AMD GPUs in desktop or workstation environments may also be affected, especially if debugfs is enabled and accessible.

European organizations should ensure that all Linux systems using AMDGPU drivers are updated to the latest kernel versions that include the patches addressing CVE-2021-47489. Specifically, they should verify that the kernel includes the fixes committed in October 2021 and subsequent updates that cover all out-of-bounds write issues in amdgpu_dm_debugfs.c. Additionally, organizations should restrict access to debugfs by unmounting it where not required or limiting permissions to trusted administrators only. Implementing strict local user access controls and monitoring for unusual debugfs interactions can help detect potential exploitation attempts. Employing kernel security modules such as SELinux or AppArmor to confine access to debugfs interfaces can further reduce risk. Regular vulnerability scanning and patch management processes should prioritize Linux kernel updates, especially for systems with AMD GPUs. Finally, organizations should review and harden local user privileges to minimize the risk of privilege escalation via local vulnerabilities.