NULL Pointer Dereference in VRAM Logic for AMD APU Devices

CVE-2025-40288

What is CVE-2025-40288?

A vulnerability exists in the Linux kernel affecting AMD APU devices due to a NULL pointer dereference in the VRAM management logic. Specifically, uninitialized VRAM managers cause the ttm_resource_manager_usage() function to access a NULL pointer, leading to system instability. The vulnerability is particularly prevalent in APU platforms, where the device backing pointer remains uninitialized due to the absence of dedicated VRAM. Enhanced checks have been implemented to prevent this occurrence, including skipping VRAM-specific logic for uninitialized managers and ensuring safe access to memory reporting functions. This makes the kernel more robust against potential dereferences of NULL pointers across various device scenarios.

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