CVE-2026-23039

In the Linux kernel, the following vulnerability has been resolved:

drm/gud: fix NULL fb and crtc dereferences on USB disconnect

On disconnect drm_atomic_helper_disable_all() is called which
sets both the fb and crtc for a plane to NULL before invoking a commit.

This causes a kernel oops on every display disconnect.

Add guards for those dereferences.

More information : https://git.kernel.org/stable/c/a255ec07f91d4c73a361a28b7a3d82f5710245f1