CVE-2023-53291: 
Linux Kernel vulnerability analysis and mitigation

A vulnerability has been identified in the Linux kernel related to the RCU (Read-Copy-Update) subsystem, specifically in the rcuscale module. The issue was discovered and disclosed on September 16, 2025, and is tracked as CVE-2023-53291. The vulnerability affects the kfreescalethread functionality in the Linux kernel's RCU implementation (NVD).

The vulnerability occurs when the kfreescalethread thread(s) continue running after unloading the rcuscale module. This leads to a page fault error when attempting to access memory that is no longer valid. The issue manifests specifically when running the 'kfreercutest' test case, resulting in a supervisor instruction fetch kernel mode page fault. The error occurs at address ffffffffc0601a87 with error code 0x0010, indicating a not-present page (NVD).

When exploited, this vulnerability can cause a kernel crash due to the inability to handle page faults properly. This results in system instability and potential denial of service conditions as evidenced by the reported kernel oops message (NVD).

The issue has been resolved by invoking kfreescalecleanup() from rcuscalecleanup() when removing the rcuscale module. This ensures proper cleanup of kfreescalethread threads before module unload (NVD).