⬢ DragonFlyBSD Kernel Audit
DF-4637 / manifest.json
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{
  "verdict": "untested (hardware-gated; mechanism source-certain)",
  "impact": "local/physical DoS — multi-second per-CPU preemption+interrupt blackout per I/O, repeatable",
  "reproduce": {
    "build": "nothing to build",
    "run": "hardware setup: ppc(4)+vpo(4) ZIP as /dev/daN with malicious emulator withholding nBUSY; then `dd if=/dev/da1 of=/dev/null bs=512 count=1` (see trigger.sh)",
    "expected": "issuing CPU spins up to ~13M status-register polls (5000 select + 16x500000 cmd + 5000000 data) inside one crit_enter; watchdog/soft-lockup symptoms per I/O"
  },
  "kernel_refs": [
    "sys/dev/disk/vpo/vpoio.c:59-60",
    "sys/dev/disk/vpo/vpoio.c:103-113",
    "sys/dev/disk/vpo/vpoio.c:525-558",
    "sys/dev/disk/vpo/vpoio.c:705-716",
    "sys/dev/disk/vpo/vpoio.c:733",
    "sys/dev/disk/vpo/vpoio.c:774",
    "sys/dev/disk/vpo/vpo.c:215-323",
    "sys/dev/misc/ppc/ppc.c:1447-1458"
  ],
  "artifacts": ["README.md", "VERDICT.md", "trigger.sh", "fix.diff", "env.txt", "verdict.json", "manifest.json"]
}