Bug 2468088 (CVE-2026-43305)

Summary: CVE-2026-43305 kernel: drm/amd/display: Fix mismatched unlock for DMUB HW lock in HWSS fast path
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
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Priority: low    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in the drm/amd/display component of the Linux kernel. A mismatched unlock operation for the DMUB hardware (HW) lock in the HWSS fast path can occur. This happens because the logic for determining when to use the lock differs from the logic for when to unlock it. When the fast path is utilized on systems without FAMS (Fast Access Memory Support) hardware, this discrepancy can lead to a system hang, resulting in a Denial of Service (DoS).
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Description OSIDB Bzimport 2026-05-08 14:03:54 UTC 
In the Linux kernel, the following vulnerability has been resolved:

drm/amd/display: Fix mismatched unlock for DMUB HW lock in HWSS fast path

[Why]
The evaluation for whether we need to use the DMUB HW lock isn't the
same as whether we need to unlock which results in a hang when the
fast path is used for ASIC without FAMS support.

[How]
Store a flag that indicates whether we should use the lock and use
that same flag to specify whether unlocking is needed.
Comment 1 Keith Grant 2026-05-08 18:45:09 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026050858-CVE-2026-43305-b13c@gregkh/T