UMR QP Recovery Flow Vulnerability in Linux Kernel: CVE-2025-21892
Summary
CVE-2025-21892: In the Linux kernel, the following vulnerability has been resolved: RDMA/mlx5: Fix the recovery flow of the UMR QP This patch addresses an issue in the recovery flow of the UMR QP, ensuring tasks do not get stuck, as hig... Affects linux versions 6.1.106-1 – 6.9.9-1. No fix is published. How to fix ↓
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Background
The Linux kernel is the core component of many operating systems, providing essential services for hardware and software interaction. It supports various functionalities, including process management, memory management, and device control. The kernel is critical for system stability and performance. This specific vulnerability affects the RDMA (Remote Direct Memory Access) subsystem, particularly the mlx5 driver, which is responsible for high-performance networking. The vulnerability can lead to tasks getting stuck during recovery processes, impacting system reliability.
Vulnerability Detail
CVE-2025-21892 is a race condition vulnerability in the recovery flow of the UMR (User Memory Region) Queue Pair (QP) in the Linux kernel's RDMA subsystem. It arises when the software fails to wait for all outstanding Work Requests (WRs) to complete before transitioning the QP to the RESET state. This oversight can cause the firmware to skip sending some flushed Completion Queue Entries (CQEs) with errors, leading to lost CQEs and tasks becoming unresponsive. The vulnerability is critical as it can severely affect system performance and reliability, especially in high-throughput environments.
How To Fix
No fixed version is published for this vulnerability.
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Workaround
As a temporary workaround, you can disable the hung task timeout message by executing the following command: echo 0 > /proc/sys/kernel/hung_task_timeout_secs. However, this does not fix the underlying issue and should only be used as a short-term measure.
Conclusion
CVE-2025-21892 is a significant vulnerability in the Linux kernel's RDMA subsystem that can lead to system instability. It is crucial to apply the necessary updates to ensure system reliability and performance. Users are encouraged to monitor for patches and utilize tools like Vulert to stay informed about vulnerabilities in their applications.
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FAQ
CVE-2025-21892 is a vulnerability in the Linux kernel's RDMA subsystem that can cause tasks to become unresponsive during recovery processes.
This vulnerability can lead to lost Completion Queue Entries and tasks getting stuck, which can severely impact system performance and reliability.
You should update your Linux package to the patched version as soon as it becomes available to mitigate the risk of this vulnerability.
Yes, you can disable the hung task timeout message temporarily, but this does not resolve the underlying issue.
You can use Vulert, which monitors and alerts for open-source vulnerabilities in real-time. You can check your application using the Vulert playground without any signup at Vulert Scanner.
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