CVE-2021-47458 is a vulnerability identified in the Linux kernel affecting the OCFS2 (Oracle Cluster File System version 2) filesystem driver. The issue arises when mounting an OCFS2 filesystem using either the o2cb or pcmk cluster stack on Linux kernels starting from version 5.11 compiled with the CONFIG_FORTIFY_SOURCE option enabled. The root cause is that the cluster stack and cluster name strings stored on disk are not guaranteed to be null-terminated, but the kernel code uses strlcpy and strlen functions that assume null-termination. This mismatch leads to a read beyond the intended buffer boundary during the mount operation, triggering a buffer overflow detection and causing a kernel panic (BUG). The vulnerability manifests as a kernel crash with a buffer overflow detected in strlen, resulting in a denial of service (DoS) condition. The stack trace shows the failure occurs during the ocfs2_initialize_super and ocfs2_fill_super functions, which are responsible for mounting and initializing the OCFS2 filesystem. Since this vulnerability triggers a kernel panic, it can cause system instability or downtime on affected systems. The flaw is due to improper handling of string termination in on-disk metadata, which is a logic error in the OCFS2 filesystem driver. No known exploits are reported in the wild as of the publication date. The vulnerability affects Linux kernel versions 5.11 and later with CONFIG_FORTIFY_SOURCE enabled and using OCFS2 with cluster stacks o2cb or pcmk. No CVSS score has been assigned yet.

For European organizations, this vulnerability poses a risk primarily to systems running Linux kernels 5.11 or newer with OCFS2 filesystems configured with cluster stacks o2cb or pcmk. OCFS2 is typically used in clustered environments requiring shared storage, such as database clusters or high-availability systems. Exploitation leads to a kernel panic and system crash during mount operations, causing denial of service. This can disrupt critical services relying on clustered storage, impacting availability and potentially causing operational downtime. Confidentiality and integrity impacts are limited since the vulnerability does not allow arbitrary code execution or privilege escalation directly. However, repeated crashes or forced reboots can lead to data unavailability and operational interruptions. European enterprises with clustered Linux environments, especially in sectors like finance, telecommunications, and manufacturing that rely on high-availability storage clusters, may be affected. The vulnerability could also impact cloud providers and data centers in Europe that use OCFS2 for clustered storage solutions. Given the kernel panic nature, the threat is more about availability disruption than data breach or system compromise.

1. Upgrade the Linux kernel to a version where this vulnerability is patched. Monitor official Linux kernel repositories and vendor advisories for updates addressing CVE-2021-47458. 2. If upgrading immediately is not feasible, avoid mounting OCFS2 filesystems with cluster stacks o2cb or pcmk on affected kernel versions compiled with CONFIG_FORTIFY_SOURCE enabled. 3. Review cluster storage configurations and consider alternative cluster filesystems or storage solutions that do not exhibit this vulnerability. 4. Implement monitoring to detect kernel panics or mount failures related to OCFS2 filesystems to enable rapid incident response. 5. For critical systems, schedule maintenance windows to apply patches and test cluster mounts to prevent unexpected downtime. 6. Engage with Linux distribution vendors for backported patches if using long-term support kernels. 7. Ensure backups and disaster recovery plans are current to mitigate potential data availability issues caused by unexpected crashes.