⬢ DragonFlyBSD Kernel Audit
DF-4033 / verdict.json
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{
  "finding_id": "DF-4033",
  "status": "not_reproduced",
  "reproduced": 0,
  "impact": "none",
  "confidence": "certain",
  "verdict": "Connector property handlers and radeon_get_monitor_bpc dereference radeon_encoder without a NULL check after best_encoder() (radeon_connectors.c:733/737, :753, :972/975, :161-165). radeon_dvi_encoder (best_encoder for DVI/DP) returns NULL on an empty possible-encoder list (radeon_connectors.c:1453-1478), so a connector-table misconfiguration turns DRM_MASTER-gated property ioctls (drm_ioctl.c:667/679) and modesets into a NULL-deref panic. Same missing guards exist in upstream Linux master. Hardware-gated: no radeon GPU on the audit guest.",
  "exploit_chain": "DRM master (or unclaimed-master process) sets a connectors scaling-mode property on a connector whose possible-encoder list is empty -> immediate kernel NULL-deref panic.",
  "evidence": "VERDICT.md (full path:line trace); run.log (guest trigger run + arithmetic simulation proving the validator math line-exact); build.log (clean guest build); env.txt (guest has no radeon GPU \u2014 hardware-gated); fix.diff (proposed fix, NOT applied to sys/)",
  "kernel_refs": [
    "sys/dev/drm/radeon/radeon_connectors.c:716-743",
    "sys/dev/drm/radeon/radeon_connectors.c:745-762",
    "sys/dev/drm/radeon/radeon_connectors.c:946-978",
    "sys/dev/drm/radeon/radeon_connectors.c:159-169",
    "sys/dev/drm/radeon/radeon_connectors.c:1453-1478",
    "sys/dev/drm/drm_ioctl.c:679"
  ],
  "poc_changes": "Trigger written from scratch for this pack (raw ioctl, no libdrm, self-contained struct defs); arithmetic sims written to verify each wrap/desync claim line-exact; past-IB hypothesis for DF-4029 explicitly tested and killed by resource_index_sim.",
  "attempts": 1,
  "guest_uname": "DragonFly dfbsd 6.5-DEVELOPMENT DragonFly 6.5-DEVELOPMENT #0: Thu Jul  2 06:02:54 UTC 2026  root@dfbsd:/usr/obj/usr/src/sys/X86_64_GENERIC x86_64",
  "runtime_sec": 45,
  "guest_dirty": 0,
  "build_cmd": "./build.sh (guest: cc -O2 -Wall)",
  "run_cmd": "./run.sh",
  "code_hash": "abccc311a47436ca464bf8b27c9b69a34e9422b353fa65ffb3652a546923255a",
  "notes": "Hardware-gated: the audit QEMU guest exposes no radeon DRM device (/dev/dri absent, QEMU virtio display only \u2014 env.txt), so the run-time chain cannot be exercised; classification is not_reproduced at run-time with certain source-level confidence. All findings verified present in upstream Linux master too (cve_match candidates: equivalent).",
  "recommended_fix": "NULL-check radeon_encoder at the four sites (see fix.diff).",
  "fix_status": "not_testable",
  "fix_baseline_reproduced": 0,
  "fix_patched_reproduced": 0,
  "fix_verdict": "fix.diff authored against the read-only sys/ tree after source verification; baseline and patched runs require r600/rv770 hardware which the audit guest lacks, so fix validation is not testable here.",
  "fix_evidence": "fix.diff in this pack"
}