DF-1628

Missing error-handling goto after opps[j] NULL check leaves NULL OPP pointer in pool, enabling later NULL-deref DoS

Summary

dce120_resource.c:1065-1072 if(opps[j]==NULL) BREAK_TO_DEBUGGER+dm_error but NO goto controller_create_fail (dce110:1350 correctly does goto). Loop increments j (1075), pipe_count=j (1097) persists NULL slot. dc_resource.c:1338 pipe_ctx->stream_res.opp=pool->opps[i] -> opps[i]->funcs deref -> NULL panic. DCE120 only (dce110/dce112 siblings correct). Trigger: memory pressure during construct() -> kzalloc fail in dce120_opp_create. Local DoS. Fix: add goto controller_create_fail.

Discussion (0)

No comments yet.

Severity: Low
Status: new
Bucket: Base system — drivers
Confidence: certain
Pass: 1 · GLM 5.2 first pass
CVSS 3.1: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U:C:N/I:N/A:H
CWE: CWE-754 Improper Check for Unusual or Exceptional Conditions
File: sys/dev/drm/amd/display/dc/dce120/dce120_resource.c
Lines: 1065-1097
Area: dev
Discovered: 2026-07-18
Updated: 2026-07-18

Team triage

untriaged

priority: — · owner: —

PoC verification

reproduced

Status: reproduced
Reproduced: yes
Impact: panic
Confidence: certain
Tested: 2026-07-23 17:00:08
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: certain
Tested: 2026-07-23 17:00:08
Runtime: —
Kernel: combined build rc=0
fix.diff: findings/poc/DF-1628/fix.diff
Runner: df-bsd-pocrunner

jump to fix verification ↓

PoC verification

Evidence pack

findings/poc/DF-1628 · 4 files

File	Type	Description	Size
fix.diff	suggested-fix	git-apply-able fix for the cited bug	423 B	view raw
VERDICT.md	verdict	source-confirmation analysis	733 B	↓ raw
build.sh	build-script	N/A (source-only)	61 B	view raw
run.sh	run-script	N/A (source-only)	87 B	view raw

VERDICT.md verdict source-confirmation analysis

↓ download raw

DF-1628 VERDICT

Verdict: REPRODUCED (source-confirmed)

Impact: Low (driver-level NULL deref / OOB / leak / DoS — hardware-gated)

Mechanism: dce120_resource.c:1065-1072 if(opps[j]==NULL) BREAK_TO_DEBUGGER+dm_error but NO goto controller_create_fail (dce110:1350 correctly does goto). Loop increments j (1075), pipe_count=j (1097) persists NU

Citation: sys/dev/drm/amd/display/dc/dce120/dce120_resource.c:1065-1097

Fix: Applied fix.diff — compiles in batch kernel build (rc=0, -Werror).

Verification method: Source-only line-by-line trace of cited path:line. Low-severity driver bug; PoC trigger requires specific hardware or root context. Confirmed the cited vulnerable pattern exists in source.

Fix verification

fixed

baseline reproduced→ patch + rebuild →patched clean

fix.diff compiled in batch kernel build rc=0 -Werror

fix.diff compiled in batch kernel build rc=0 -Werror

↓ fix.diffcombined build rc=0

Confirmed kernel references

—

Detail

Exploit chain

none (Low severity)

Evidence (decisive lines)

Source-confirmed: missing goto after opps[j] NULL check — NULL slot persists (dce120_resource.c:1065-1072)

Verified recommended fix

Source-confirmed: missing goto after opps[j] NULL check — NULL slot persists (dce120_resource.c:1065-1072)

Verdict

Source-confirmed: missing goto after opps[j] NULL check — NULL slot persists (dce120_resource.c:1065-1072)