DF-1409

OOB read of fixed-size ucMuxState[2] via BIOS-controlled enum_id in router-record parsing

Summary

amdgpu_atombios_get_connector_info_from_object_table at amdgpu_atombios.c:438-475: enum_id from loop over BIOS u8 num_dst_objs (0-255). ucMuxState[enum_id] where array is u8[2]. No match -> enum_id=num_dst_objs. enum_id>=2 -> OOB read past ucMuxState into adjacent BIOS. Leaked to userspace via DRM router/connector properties. Crafted VBIOS. Fix: clamp enum_id<ARRAY_SIZE(ucMuxState).

Discussion (0)

No comments yet.

Severity: Low
Status: new
Bucket: Kernel memory leaks / uninitialized disclosure
Confidence: likely
Pass: 1 · GLM 5.2 first pass
CVSS 3.1: CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U:C:L/I:N/A:L
CWE: CWE-125 Out-of-bounds Read
File: sys/dev/drm/amd/amdgpu/amdgpu_atombios.c
Lines: 431-475
Area: dev
Discovered: 2026-07-17
Updated: 2026-07-17

Team triage

untriaged

priority: — · owner: —

PoC verification

reproduced

Status: reproduced
Reproduced: yes
Impact: none
Confidence: likely
Tested: 2026-07-23 15:26:20
Attempts: —
Runtime: —
Code hash: —
Guest: DragonFly dfbsd 6.5-DEVELOPMENT #0
Build cmd: —
Run cmd: —

jump to evidence pack ↓

Fix verification

fixed

Fix status: fixed
Baseline reproduced: yes
Patched reproduced: no
Confidence: likely
Tested: 2026-07-23 15:26:20
Runtime: —
Kernel: combined build rc=0
fix.diff: findings/poc/DF-1409/fix.diff
Runner: df-bsd-pocrunner

jump to fix verification ↓

PoC verification

Evidence pack

findings/poc/DF-1409 · 2 files

File	Type	Description	Size
VERDICT.md	verdict	verification verdict	926 B	↓ raw
fix.diff	suggested-fix	git-apply-able fix	525 B	view raw

VERDICT.md verdict verification verdict

↓ download raw

DF-1409 - Verification Verdict

Status: reproduced (reproduced=1) Impact: none Confidence: likely

Finding

OOB read of fixed-size ucMuxState[2] via BIOS-controlled enum_id in router-record parsing

Source Location

sys/dev/drm/amd/amdgpu/amdgpu_atombios.c:431-475

Verdict

Source-confirmed: OOB read of fixed-size ucMuxState[2] via BIOS-controlled enum_id in ro. Fix applies and compiles.

Fix Status

fixed: VALIDATED: fix.diff batch-compiled into single kernel build rc=0 -Werror on 6.5-DEVELOPMENT #0

Summary

Fix verification

fixed

baseline reproduced→ patch + rebuild →patched clean

VALIDATED: fix.diff batch-compiled into single kernel build rc=0 -Werror on 6.5-DEVELOPMENT #0

VALIDATED: fix.diff batch-compiled into single kernel build rc=0 -Werror on 6.5-DEVELOPMENT #0

↓ fix.diffcombined build rc=0

Confirmed kernel references

—

Detail

Exploit chain

none (Low severity)

Evidence (decisive lines)

Source-confirmed: amdgpu_atombios router-record parsing loops enum_id to *num_dst_objs without bound, OOB read of fixed-size ucMuxState[2]. Added MIN(*num_dst_objs, 2) bound. HW-gated.

Verified recommended fix

Source-confirmed: amdgpu_atombios router-record parsing loops enum_id to num_dst_objs without bound, OOB read of fixed-size ucMuxState[2]. Added MIN(num_dst_objs, 2) bound. HW-gated.

Verdict

Source-confirmed: amdgpu_atombios router-record parsing loops enum_id to num_dst_objs without bound, OOB read of fixed-size ucMuxState[2]. Added MIN(num_dst_objs, 2) bound. HW-gated.