CVE-2025-40232 in Linux
Summary
by MITRE • 12/04/2025
In the Linux kernel, the following vulnerability has been resolved:
rv: Fully convert enabled_monitors to use list_head as iterator
The callbacks in enabled_monitors_seq_ops are inconsistent. Some treat the iterator as struct rv_monitor *, while others treat the iterator as struct list_head *.
This causes a wrong type cast and crashes the system as reported by Nathan.
Convert everything to use struct list_head * as iterator. This also makes enabled_monitors consistent with available_monitors.
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Analysis
by VulDB Data Team • 02/23/2026
The vulnerability CVE-2025-40232 represents a critical type casting inconsistency within the Linux kernel's display monitoring subsystem that can lead to system crashes and potential security implications. This issue affects the rv driver's handling of monitor enablement states through the enabled_monitors sequence operations interface. The root cause stems from inconsistent pointer type handling in the iterator mechanism used to traverse monitor information structures, creating a fundamental flaw in the kernel's memory management and data access patterns.
The technical flaw manifests as a type confusion error where different callback functions within the enabled_monitors_seq_ops interface treat the same iterator parameter with conflicting type assumptions. Some functions expect the iterator to be a struct rv_monitor pointer while others assume it to be a struct list_head pointer, leading to improper memory dereferencing and corrupted data access patterns. This inconsistency directly violates the principle of consistent data type handling that is fundamental to kernel stability and security. The vulnerability specifically impacts the rv driver's monitor management functionality and demonstrates a classic case of improper pointer arithmetic and type casting that can be exploited to cause kernel panics or system crashes.
The operational impact of this vulnerability extends beyond simple system instability to potentially compromise the integrity of the display subsystem and overall system reliability. When the system encounters this inconsistency during monitor enumeration or state management operations, it results in immediate kernel crashes that can disrupt user sessions and potentially allow for denial of service attacks against critical display functionality. The vulnerability affects systems utilizing the rv driver for graphics monitoring and management, particularly those implementing dynamic monitor enablement features. This type of flaw can be particularly dangerous in embedded systems or server environments where display management is critical for system monitoring and administration.
The fix implemented addresses this issue by standardizing all iterator usage within the enabled_monitors interface to consistently employ struct list_head * as the iterator type, aligning it with the established pattern used in available_monitors. This approach resolves the type casting inconsistencies and ensures proper memory access patterns throughout the monitoring subsystem. The solution follows established kernel development practices for maintaining data structure consistency and preventing type confusion errors that could lead to kernel exploitation. This fix aligns with the common security principle of minimizing attack surface through consistent and predictable memory management patterns. The remediation also improves code maintainability and reduces the likelihood of similar issues arising in future kernel modifications. The vulnerability demonstrates the importance of rigorous type checking and consistent interface design in kernel space programming, particularly when dealing with complex data structures and iterator patterns that are fundamental to system stability and security.