Address Space Leak in Linux Kernel's Hyper-V DRM Device Management
Summary
CVE-2025-21978: In the Linux kernel, the following vulnerability has been resolved: drm/hyperv: Fix address space leak when Hyper-V DRM device is removed When a Hyper-V DRM device is probed, the driver allocates MMIO space for the vram,... Affects linux versions < 6.1.133-1. Fixed in 6.1.133-1. How to fix ↓
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Background
The Linux kernel is a core component of many operating systems, providing essential services for hardware management and system resources. It supports a wide range of devices and functionalities, including graphics processing through the Direct Rendering Manager (DRM). The Hyper-V DRM device allows for enhanced graphics performance in virtualized environments. However, vulnerabilities in the kernel can lead to significant security risks, including memory leaks and unauthorized access to system resources.
Vulnerability Detail
In the Linux kernel, a vulnerability was identified in the handling of the Hyper-V DRM device. When the device is probed, the driver allocates Memory-Mapped Input/Output (MMIO) space for video RAM (vram) and maps it as cacheable. If the device is removed or encounters an error during probing, the MMIO space is released without unmapping it, leading to a leak of the kernel address space. This leak can potentially be exploited to access sensitive information or cause instability in the system.
How To Fix
Minimum fixed version
6.1.133-1
This is the first release that contains the fix.
sudo apt-get install --only-upgrade linuxTip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
Currently, there are no specific workarounds mentioned for this vulnerability. The best course of action is to apply the patch as soon as it becomes available.
Conclusion
The CVE-2025-21978 vulnerability in the Linux kernel's Hyper-V DRM device poses a significant risk due to the potential for address space leaks. Users are encouraged to update their systems to the patched version to mitigate this risk. Monitoring tools like Vulert can assist in identifying vulnerabilities in your applications.
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FAQ
CVE-2025-21978 is a vulnerability in the Linux kernel related to the Hyper-V DRM device that can lead to an address space leak.
This vulnerability can potentially allow unauthorized access to kernel memory, leading to security risks and system instability.
Yes, a patch is available for Debian 13 in version 6.12.20-1. Users should update their kernel to this version.
While there are no specific workarounds, it is advisable to monitor your system for any unusual behavior and apply the patch as soon as possible.
You can use Vulert, which allows you to monitor and alert for open-source vulnerabilities in your software using a manifest file like package-lock.json. You can check your application at the Vulert playground without any signup.
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