DF-4822

DCE110v output regamma mode is never engaged: configure_regamma_mode() discards its computed value and writes literal 0, and dce110_opp_set_regamma_mode_v() is an empty stub — user-programmed gamma LUT silently bypassed

Summary

The computed GAMMA_CORR_MODE value is discarded and literal 0 (bypass) written; the mode-switch entry point is an empty TODO stub - the just-programmed PWL LUT is never selected, so a DRM-master's per-CRTC gamma is silently ignored on DCE11 virtual-transform hardware. Pure color-management correctness (LUT walks bounds-proven clean this pass); byte-identical upstream v4.15/v6.1. Write-value + implement-stub fix.

Discussion (0)

No comments yet.

Severity: Info
Status: new
Bucket: Base system — drivers
Confidence: certain
Pass: 2 · GLM 5.3 second pass
CVSS 3.1: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:N
CWE: CWE-1164
File: sys/dev/drm/amd/display/dc/dce110/dce110_opp_regamma_v.c
Lines: 111-555
Area: dev
Discovered: 2026-09-24
Updated: 2026-09-24

Team triage

untriaged

priority: — · owner: —

PoC verification

untested

Status: untested
Reproduced: no
Impact: none
Confidence: certain
Tested: 2026-09-24 05:32:44
Attempts: 0
Runtime: —
Code hash: —
Guest: —
Build cmd: —
Run cmd: —

jump to evidence pack ↓

Fix verification

not_testable

Fix status: not_testable
Baseline reproduced: —
Patched reproduced: —
Confidence: certain
Tested: 2026-09-24 05:32:44
Runtime: —
Kernel: per-fix-DF-4822
fix.diff: findings/poc/DF-4822/fix.diff
Runner: df-bsd-reviewer

jump to fix verification ↓

PoC verification

Evidence pack

findings/poc/DF-4822 · 1 files

File	Type	Description	Size
verdict.json	file		997 B	view raw

Fix verification

not_testable

per-fix-DF-4822

Confirmed kernel references

Detail

Exploit chain

none - display color management only

Evidence (decisive lines)

findings/poc/DF-4822/ (this verdict)

Verdict

Functional correctness (no security impact): configure_regamma_mode builds the GAMMA_CORR_MODE value then writes literal 0 (bypass) instead of it, and dce110_opp_set_regamma_mode_v is an empty TODO stub - the just-programmed PWL LUT (all walks bounds-proven this pass) is never actually selected by the hardware, so a DRM-master's per-CRTC gamma is silently ignored on DCE11 'virtual' transform hardware (Carrizo/Stoney). Byte-identical upstream v4.15 and still v6.1 (upstream-fix-worthy). Write-the-value + implement-the-stub fix.