CVE-2018-14734 in Linux
Summary
by MITRE
drivers/infiniband/core/ucma.c in the Linux kernel through 4.17.11 allows ucma_leave_multicast to access a certain data structure after a cleanup step in ucma_process_join, which allows attackers to cause a denial of service (use-after-free).
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Analysis
by VulDB Data Team • 04/27/2023
The vulnerability identified as CVE-2018-14734 resides within the Linux kernel's InfiniBand subsystem, specifically in the ucma.c driver file that manages userspace communication with InfiniBand devices. This flaw represents a classic use-after-free vulnerability that occurs during the processing of multicast group membership operations. The issue manifests when the ucma_leave_multicast function attempts to access a data structure that has already been freed during the execution of ucma_process_join function, creating a scenario where memory that has been deallocated is still being referenced. Such memory corruption vulnerabilities are particularly dangerous as they can lead to system instability and potential privilege escalation opportunities.
The technical implementation of this vulnerability stems from improper memory management within the InfiniBand communication stack. When a userspace application joins a multicast group through the UCMA (User Channel Management API) interface, the kernel performs several operations including memory allocation and state tracking. However, the cleanup process that occurs in ucma_process_join does not properly invalidate references to the data structures that are subsequently accessed by ucma_leave_multicast. This creates a window where the memory management subsystem has deallocated resources but the code path continues to reference those freed locations, resulting in undefined behavior and system crashes.
From an operational perspective, this vulnerability presents a significant denial of service risk to systems running affected Linux kernel versions through 4.17.11. Attackers can exploit this flaw by crafting specific sequences of multicast join and leave operations that trigger the use-after-free condition, causing the kernel to crash and potentially leading to system-wide service disruption. The impact extends beyond simple service interruption as the vulnerability can be leveraged to destabilize network services that rely on InfiniBand connectivity, affecting high-performance computing clusters, data center infrastructures, and enterprise networking environments where such kernel-level communication channels are critical. The vulnerability affects systems where InfiniBand hardware is present and where userspace applications interact with the UCMA interface for channel management operations.
The vulnerability aligns with CWE-416, which specifically addresses use-after-free conditions in software systems, and demonstrates how improper memory management can create exploitable conditions in kernel space. From an ATT&CK framework perspective, this vulnerability maps to techniques involving privilege escalation and system instability through kernel exploitation, potentially allowing adversaries to gain unauthorized access to system resources or disrupt critical services. The exploitation requires minimal privileges since it operates within the kernel's communication interfaces, making it particularly concerning for environments where multiple users or applications may interact with InfiniBand subsystems. Mitigation strategies should include immediate kernel updates to versions that contain the fix, which typically involves proper synchronization of memory cleanup operations with access patterns, ensuring that data structures are not referenced after deallocation. Additionally, system administrators should monitor for abnormal kernel crashes or network service disruptions that could indicate exploitation attempts, and consider implementing network segmentation to limit the potential impact of such vulnerabilities within larger infrastructures.