Bug 2435658 (CVE-2026-23039)

Summary: CVE-2026-23039 kernel: drm/gud: fix NULL fb and crtc dereferences on USB disconnect
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Version: unspecifiedKeywords: Security
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OS: Linux   
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A NULL pointer dereference vulnerability was found in the Linux kernel's GUD (Generic USB Display) driver. When a USB display is disconnected, drm_atomic_helper_disable_all() sets the framebuffer and CRTC pointers to NULL before invoking a commit. The driver then attempts to dereference these NULL pointers, causing a kernel crash on every USB display disconnect event.
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Description OSIDB Bzimport 2026-01-31 12:02:11 UTC 
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.
Comment 1 Alexander B 2026-02-02 09:54:49 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026013122-CVE-2026-23039-be18@gregkh/T