CVE-2011-0695 in Linux
Summary
by MITRE
Race condition in the cm_work_handler function in the InfiniBand driver (drivers/infiniband/core/cma.c) in Linux kernel 2.6.x allows remote attackers to cause a denial of service (panic) by sending an InfiniBand request while other request handlers are still running, which triggers an invalid pointer dereference.
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Analysis
by VulDB Data Team • 10/19/2021
The vulnerability described in CVE-2011-0695 represents a critical race condition flaw within the Linux kernel's InfiniBand communication subsystem, specifically within the connection management architecture. This issue affects kernel versions 2.6.x and manifests in the cm_work_handler function located in the drivers/infiniband/core/cma.c file, which governs the handling of InfiniBand communication management work items. The race condition occurs when multiple concurrent InfiniBand requests are processed simultaneously, creating a temporal window where the system state becomes inconsistent and potentially leads to system instability.
The technical exploitation of this vulnerability hinges on the improper synchronization mechanisms within the kernel's InfiniBand driver implementation. When a remote attacker sends an InfiniBand request while other request handlers are still executing, the cm_work_handler function fails to properly manage shared resources and state variables. This concurrency issue results in an invalid pointer dereference scenario where the kernel attempts to access memory locations that have already been freed or are otherwise inaccessible. The flaw stems from inadequate locking mechanisms and improper state validation during concurrent request processing, creating a scenario where the kernel's memory management subsystem encounters corrupted pointers that lead to immediate system panic and complete denial of service.
The operational impact of this vulnerability extends beyond simple service disruption, as it can be leveraged by remote attackers to systematically destabilize systems relying on InfiniBand networking infrastructure. Systems utilizing high-performance computing clusters, data center networks, or any environment where InfiniBand communication is critical become vulnerable to this attack vector. The denial of service condition manifests as kernel panic, which can result in complete system crashes requiring manual reboot and potentially leading to data loss or service interruptions in mission-critical environments. This vulnerability particularly affects enterprise systems where InfiniBand is used for high-speed interconnects between servers and storage arrays, making it a significant concern for data center administrators and security professionals managing large-scale computing infrastructures.
Mitigation strategies for this vulnerability require immediate kernel updates to patched versions that address the race condition through proper synchronization mechanisms and memory management. System administrators should prioritize applying security patches that implement appropriate mutex locking or spinlock mechanisms to prevent concurrent access to shared resources during request processing. Additionally, network segmentation and access controls should be implemented to limit exposure to this vulnerability by restricting direct access to InfiniBand communication endpoints. The underlying architectural issue aligns with CWE-362, which identifies race conditions as a fundamental security weakness, while the exploitation pattern corresponds to ATT&CK technique T1499.004, focusing on network denial of service attacks that leverage system instability. Organizations should also implement monitoring solutions to detect anomalous InfiniBand traffic patterns that could indicate exploitation attempts and establish robust incident response procedures to handle potential system panics resulting from this vulnerability.