Bug 2535131 (CVE-2026-89819)

Summary: CVE-2026-89819 kernel: drm/amd/display: validate plane degamma LUT size for private color prop
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: akhatavk, aos-team-art-private, asdas, dpaolell, jdelft, jupierce, lgarciaa, mbiarnes, ppalepu, ppostler, prdhamdh, rhel-process-autobot, sghai, sidsharm, suppawar, vlaad, watson-tool-maintainers
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's drm/amd/display component. This vulnerability arises from insufficient validation of the plane degamma Look-Up Table (LUT) size. A local attacker, with access to the AMD_PLANE_DEGAMMA_LUT property (available on systems with AMD_PRIVATE_COLOR defined), could provide a malformed input. This could lead to a divide-by-zero error, resulting in a Denial of Service (DoS), or an out-of-bounds read, potentially causing information disclosure.
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Description OSIDB Bzimport 2026-09-16 10:54:50 UTC 
In the Linux kernel, the following vulnerability has been resolved:

drm/amd/display: validate plane degamma LUT size for private color prop

Unlike the CRTC degamma path, which is guarded by
amdgpu_dm_verify_lut_sizes(), the per-plane degamma LUT size was never
validated before use. __set_dm_plane_degamma() passed the user-supplied
size straight into __is_lut_linear() and, for a non-linear LUT, into
__set_input_tf() -> __drm_lut_to_dc_gamma(), the latter always iterating
MAX_COLOR_LUT_ENTRIES entries regardless of the actual LUT size.

A malformed AMD_PLANE_DEGAMMA_LUT blob (e.g. a single entry) could thus
trigger a divide-by-zero in __is_lut_linear() or an out-of-bounds read in
__drm_lut_to_dc_gamma(). Reject any plane degamma LUT whose size does not
match MAX_COLOR_LUT_ENTRIES, mirroring the invariant the code already
asserts a few lines below (and which the CRTC path enforces).

The AMD_PLANE_DEGAMMA_LUT property is only exposed on builds with
AMD_PRIVATE_COLOR defined.
Comment 1 Mauro Matteo Cascella 2026-09-21 16:40:57 UTC 
Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89819.mbox