{
  "finding_id": "DF-2528",
  "status": "not_reproduced",
  "reproduced": 0,
  "impact": "none",
  "confidence": "likely",
  "verdict": "A root-driven hammer (raw dd I/O on vn3 racing 8 vnconfig -u detach rounds) produced no panic - the window is narrow and the opencount gate serializes the common case. The source trace stands: struct vn_softc carries no lock; vnstrategy/vnget peek VNF_INITED/sc_vp unlocked while vnclear (VNIOCDETACH, RESTRICTEDROOT) closes the vnode, deallocates the object and NULLs the pointers (:744-756); disk_getopencount is an unlocked read. Privileged-cooperator local DoS as filed. Fix (state token serializing the strategy snapshot against vnclear) compile-validated in the vn module build; the full vnode-lifetime fix additionally needs a held reference across I/O (noted in the diff).",
  "exploit_chain": "root+operator cooperation required; ceiling: panic/UAF on a racing detach.",
  "evidence": "no crash in the hammer; vn module builds with the token fix.",
  "kernel_refs": [
    "sys/dev/disk/vn/vn.c:272",
    "sys/dev/disk/vn/vn.c:794",
    "sys/dev/disk/vn/vn.c:744",
    "sys/dev/disk/vn/vn.c:124"
  ],
  "poc_changes": "hammer only; the deterministic race driver was not built (finding is Low, privileged race).",
  "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": 400,
  "guest_dirty": 0,
  "build_cmd": "(hammer) dd/vnconfig loops",
  "run_cmd": "(for i in 1..8; do dd if=/dev/vn3 of=/dev/null bs=64k count=4; done) racing (vnconfig -u vn3 x8)",
  "code_hash": "n/a",
  "notes": "Natural race not hit in a short root-driven hammer (8 detach rounds vs raw I/O); no panic observed. Source trace stands: no lock anywhere on struct vn_softc state; vnstrategy/vnget peek VNF_INITED/sc_vp unlocked while vnclear (VNIOCDETACH, RESTRICTEDROOT) frees them. Fix (state token) compile-validated in the vn module build.",
  "recommended_fix": "serialize vnstrategy state snapshot against vnclear with a token",
  "fix_status": "compile_validated"
}