CVE-2024-35902 is a vulnerability identified in the Linux kernel's Reliable Datagram Sockets (RDS) subsystem, specifically within the Remote Direct Memory Access (RDMA) mapping functionality. The issue arises due to a potential null pointer dereference involving the 'cp' parameter in the __rds_rdma_map function. The 'cp' parameter, which represents a connection pointer, can be null when passed from certain call-sites such as rds_get_mr() and rds_get_mr_for_dest(). Prior to the patch, the code assumed 'cp' might be null but did not adequately handle this scenario, leading to a situation where dereferencing cp->cp_conn could cause a null pointer dereference and potentially crash the kernel or cause undefined behavior. The vulnerability is mitigated by adding a check to ensure 'cp' is not null before dereferencing it. The underlying problem is that the get_mr() function implementation (specifically rds_ib_get_mr()) can return an error pointer if the connection argument is null, which was not properly accounted for. This bug is essentially a robustness issue in the kernel's RDS RDMA code path, which could lead to denial of service (DoS) conditions if exploited, as a null dereference in kernel space typically results in a kernel panic or crash. There is no indication that this vulnerability allows privilege escalation or remote code execution. No known exploits are currently reported in the wild. The affected Linux kernel versions include several commits identified by their hashes, indicating the vulnerability is present in recent kernel versions prior to the patch. The patch adds necessary null checks to prevent the dereference. This vulnerability is primarily a stability and availability concern within Linux systems using RDS over RDMA, which is commonly used in high-performance computing and data center environments.

For European organizations, the primary impact of CVE-2024-35902 is the potential for denial of service due to kernel crashes triggered by null pointer dereferences in the Linux kernel's RDS RDMA subsystem. Organizations relying on Linux servers with RDS over RDMA enabled—such as those in cloud service providers, research institutions, financial services, and telecommunications—may experience service interruptions or system instability if the vulnerability is triggered. While this vulnerability does not appear to allow unauthorized access or data compromise, the resulting downtime could disrupt critical services, especially in environments requiring high availability and low latency. Given the use of RDMA in high-performance computing clusters and data centers, affected systems could see degraded performance or outages, impacting business operations and service delivery. The lack of known exploits reduces immediate risk, but unpatched systems remain vulnerable to accidental or malicious triggering of the bug. European organizations with Linux-based infrastructure should prioritize patching to maintain system stability and avoid potential operational disruptions.

1. Apply the official Linux kernel patches that address CVE-2024-35902 as soon as they become available from trusted sources or Linux distribution vendors. 2. For organizations using custom or upstream kernels, monitor kernel mailing lists and repositories for the patch and integrate it promptly into their build pipelines. 3. Disable RDS over RDMA functionality if it is not required in the environment to reduce the attack surface. 4. Implement robust monitoring of kernel logs and system stability metrics to detect early signs of null pointer dereference crashes or related kernel panics. 5. In virtualized or containerized environments, isolate critical workloads to minimize the impact of potential kernel crashes. 6. Conduct thorough testing of kernel updates in staging environments before deployment to production to ensure compatibility and stability. 7. Maintain up-to-date backups and disaster recovery plans to mitigate the impact of unexpected downtime. 8. Educate system administrators about this vulnerability and the importance of timely patching, especially in environments utilizing RDMA technologies.