Linux Kernel NULL Pointer Dereference Vulnerability in DRM VBlank Management

A NULL pointer dereference vulnerability has been identified in the Linux kernel's Direct Rendering Manager (DRM) subsystem. This issue arises in the vblank initialization process, where a NULL worker pointer can be dereferenced, leading to a crash. The vulnerability occurs in versions of the Linux kernel that include the problematic vblank management code.

Impact

Exploitation of this vulnerability leads to a NULL pointer dereference, causing a kernel crash.

Reproduction

The vulnerability can be reproduced by loading a kernel module that initializes a virtual KMS (VKMS) driver. During the initialization, the DRM vblank management system is set up. If the action to add a cleanup routine fails, the system inadvertently tries to release a vblank worker that is NULL, causing a NULL pointer dereference when the worker is destroyed.