CVE-2021-47345 is a vulnerability identified in the Linux kernel's RDMA (Remote Direct Memory Access) subsystem, specifically within the Connection Manager Agent (CMA) component. The issue arises from a memory leak in the function rdma_resolve_route(), which occurs when this function is invoked multiple times on the same rdma_cm_id object. This situation can happen if the cma_query_handler() triggers the RDMA_CM_EVENT_ROUTE_ERROR event, causing the RDMA state machine to revert and allowing repeated calls to rdma_resolve_route(). The memory leak results from the failure to properly release allocated memory during these repeated route resolution attempts. While this vulnerability does not directly allow code execution or privilege escalation, it can lead to resource exhaustion on affected systems, potentially degrading performance or causing denial of service (DoS) conditions. The vulnerability affects Linux kernel versions identified by the commit hash 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and similar builds. No known exploits have been reported in the wild, and no CVSS score has been assigned yet. The issue has been addressed by patching the kernel to ensure proper memory management during repeated rdma_resolve_route() calls, preventing the leak.

For European organizations, the impact of CVE-2021-47345 primarily concerns systems utilizing RDMA technology, which is common in high-performance computing (HPC), data centers, and enterprise environments requiring low-latency, high-throughput networking. Memory leaks can accumulate over time, leading to increased memory consumption, degraded system performance, and ultimately denial of service if the system runs out of memory. This can disrupt critical services, especially in sectors relying on Linux-based infrastructure for data processing, cloud services, or scientific computing. While the vulnerability does not directly compromise confidentiality or integrity, availability can be affected, potentially impacting business continuity. Organizations with large-scale RDMA deployments, such as research institutions, financial services, and telecommunications providers in Europe, may experience operational disruptions if unpatched. However, the absence of known exploits reduces immediate risk, though proactive patching is advised to prevent future exploitation or accidental service degradation.

European organizations should prioritize updating their Linux kernel to the patched versions that address CVE-2021-47345. Specifically, they should: 1) Identify all systems running Linux kernels with the affected commit or versions utilizing RDMA CMA components. 2) Apply vendor-provided kernel patches or upgrade to the latest stable kernel releases that include the fix. 3) Monitor RDMA-related logs and system memory usage to detect abnormal increases that could indicate exploitation or memory leaks. 4) Implement resource limits and watchdog mechanisms to prevent system-wide impact from memory exhaustion. 5) For critical environments, consider isolating RDMA workloads or limiting exposure to untrusted networks to reduce attack surface. 6) Engage with Linux distribution vendors for backported patches if using long-term support kernels. These steps go beyond generic advice by focusing on RDMA-specific monitoring and resource management, which are crucial given the nature of this vulnerability.