Memory Region Deregistration Warning in Linux Kernel - CVE-2025-21888
Summary
CVE-2025-21888: In the Linux kernel, the following vulnerability has been resolved: RDMA/mlx5: Fix a WARN during dereg_mr for DM type Memory regions (MR) of type DM (device memory) do not have an associated umem. 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 a core component of many operating systems, providing essential services for hardware and software interaction. It supports a wide range of functionalities, including process management, memory management, and device control. This vulnerability affects the RDMA (Remote Direct Memory Access) subsystem, specifically the mlx5 driver, which is responsible for managing high-performance networking and storage devices. The issue arises during the deregistration of memory regions of type DM (device memory), which do not have an associated user memory (umem).
Vulnerability Detail
In the Linux kernel, a vulnerability has been identified in the RDMA/mlx5 driver where the deregistration of memory regions of type DM incorrectly attempts to call dma_unmap_single() on a DMA address that is not mapped. This results in a warning message during the deregistration process, indicating a potential flaw in memory management. The incorrect branch selection in the code can lead to system instability or unexpected behavior, particularly in high-performance computing environments where RDMA is utilized.
How To Fix
No fixed version is published for this vulnerability.
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Workaround
Currently, there are no specific workarounds mentioned for this vulnerability. It is advisable to apply the patch as soon as it becomes available.
Conclusion
CVE-2025-21888 is a significant vulnerability in the Linux kernel's RDMA/mlx5 driver that can lead to system warnings and potential instability. Users are advised to update their packages to the latest versions to mitigate risks. Monitoring tools like Vulert can assist in identifying vulnerabilities in real-time.
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FAQ
CVE-2025-21888 is a vulnerability in the Linux kernel's RDMA/mlx5 driver that causes a warning during the deregistration of device memory regions.
The vulnerability may lead to system instability or unexpected behavior, particularly in environments utilizing RDMA for high-performance computing.
You can use Vulert to monitor and alert in real-time for open-source vulnerabilities. Visit Vulert Scanner to check if your application is affected by this vulnerability without requiring signup.
Yes, a patch is available for Debian 13 users in version 6.12.19-1. Debian 12 users should monitor for updates.
While no specific workarounds are available, it is crucial to apply the patch as soon as it becomes available to mitigate the risks associated with this vulnerability.
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