CVE-2025-21924 in Linux
Summary
by MITRE • 04/01/2025
In the Linux kernel, the following vulnerability has been resolved:
net: hns3: make sure ptp clock is unregister and freed if hclge_ptp_get_cycle returns an error
During the initialization of ptp, hclge_ptp_get_cycle might return an error and returned directly without unregister clock and free it. To avoid that, call hclge_ptp_destroy_clock to unregist and free clock if hclge_ptp_get_cycle failed.
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Analysis
by VulDB Data Team • 02/01/2026
The vulnerability CVE-2025-21924 affects the Linux kernel's networking subsystem, specifically within the hns3 driver implementation for Huawei Networking Solutions hardware. This issue represents a resource management flaw that occurs during the initialization process of Precision Time Protocol (PTP) functionality. The problem manifests when the hclge_ptp_get_cycle function fails to return successfully, yet the system does not properly clean up the PTP clock resources that were allocated during the initialization sequence. This represents a classic case of improper error handling leading to resource leakage in kernel space operations.
The technical flaw stems from a missing cleanup routine in the error path of the PTP initialization code. When hclge_ptp_get_cycle encounters an error condition during hardware clock initialization, the function returns immediately without executing the necessary cleanup operations. This failure to unregister the PTP clock and free associated memory resources creates a memory leak scenario that can accumulate over time. The vulnerability is particularly concerning because it operates within kernel space where resource exhaustion can lead to system instability, denial of service conditions, or potentially exploitable memory corruption scenarios. The flaw aligns with CWE-459, which describes incomplete cleanup issues, and specifically relates to improper cleanup of resources in kernel drivers.
The operational impact of this vulnerability extends beyond simple memory consumption, potentially affecting system reliability and performance in production environments. When multiple PTP initialization attempts fail due to hardware or configuration issues, the accumulated memory leaks can degrade system performance or cause the network driver to become unresponsive. In high-availability environments where PTP synchronization is critical for time-sensitive applications, this vulnerability could contribute to service disruption. The issue affects systems utilizing Huawei's hns3 network adapters, particularly those implementing PTP timestamping functionality, and represents a potential vector for denial of service attacks that target the network subsystem through resource exhaustion.
Mitigation strategies for CVE-2025-21924 should focus on applying the official kernel patch that ensures proper cleanup of PTP clock resources regardless of initialization success or failure. System administrators should prioritize updating their kernel versions to include the fix, particularly in production environments where network reliability is paramount. The patch implementation follows ATT&CK technique T1059.003 for kernel-level code modification, ensuring that error handling paths properly execute cleanup routines. Additional monitoring should be implemented to track memory usage patterns in network driver components, as this vulnerability could manifest as gradual memory consumption that might otherwise go unnoticed. Organizations should also consider implementing automated patch management processes to ensure timely deployment of security fixes, as this type of resource management vulnerability can accumulate silently until it reaches critical levels. The fix demonstrates proper defensive programming practices that align with secure coding guidelines for kernel development, ensuring that all resource allocation paths include corresponding deallocation routines to prevent memory leaks and maintain system stability.