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.

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	1.1 KB	↓ raw
build.sh	build-script	N/A (source-only)	65 B	view raw
run.sh	run-script	N/A (source-only)	89 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 status (batch validation)

Applied with the 36 sibling fix.diffs of this batch in findings/poc/_batch41/all_fixes.patch; single in-guest make -j6 nativekernel KERNCONF=X86_64_GENERIC completed RC=0 with zero errors under -Werror (full log: findings/poc/_batch41/fix_build8.log). Behavior A/B intentionally skipped for this Info-tier item.

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