{
  "finding_id": "DF-4172",
  "status": "untested",
  "reproduced": 0,
  "impact": "none",
  "confidence": "certain",
  "verdict": "Bug certain from line-accurate code trace, but not runtime-testable on this guest: iir_intr indexes sc_gccbs[ctx.istatus-2] (iir.c:1580) with a device-fed doorbell byte that is never range-checked (only bit 0x80 stripped, iir_pci.c:418), so a controller returning 126/127 reads/writes up to 2 gdt_ccb entries (~780 bytes) past the 124-entry kmalloc array - OOB gc_flags dispatch into gdt_free_ccb SLIST corruption (iir.c:661), wild gc_ccb deref in gdt_sync_event (iir.c:1715/1804), or wild gc_ucmd writes in the GDT_GCF_IOCTL completion (iir.c:1600-1632). Guest has no iir controller (gate_check.log: no /dev/iir, no 0x1119/Intel-0600 PCI device), and no syscall path can inject the malformed index - only the device can.",
  "exploit_chain": "",
  "evidence": "VERDICT.md (full path:line trace); gate_check.log (hardware absent); fix.diff (range check, git apply --check clean)",
  "kernel_refs": ["sys/dev/raid/iir/iir.c:1580", "sys/dev/raid/iir/iir.c:250", "sys/dev/raid/iir/iir.c:1583", "sys/dev/raid/iir/iir.c:661", "sys/dev/raid/iir/iir.c:1715", "sys/dev/raid/iir/iir_pci.c:406", "sys/dev/raid/iir/iir_pci.c:418", "sys/dev/raid/iir/iir.h:77"],
  "poc_changes": "no PoC source written: the trigger is device-fed interrupt state, unreachable from userland; only a hardware gate check was run",
  "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": 12,
  "guest_dirty": 0,
  "build_cmd": "none (no userland trigger)",
  "run_cmd": "sh gate_check.sh",
  "code_hash": "6cd1cb94653995c48b8597068012f2693c49edbc21870d9a991f2fa2c80532e8",
  "notes": "Hardware-gated (malicious/stalled controller). Even on a host with the card this is not software-triggerable. Buckets: memcorrupt. Guest artifacts (gate_check.sh) removed after capture; guest left clean and up.",
  "recommended_fix": "Range-check ctx.istatus to [2, GDT_MAXCMDS+1] before indexing sc_gccbs in iir_intr (see fix.diff)",
  "fix_status": "not_testable",
  "fix_baseline_reproduced": 0,
  "fix_patched_reproduced": 0,
  "fix_verdict": "fix.diff adds the missing bounds check and passes git apply --check; cannot be runtime-validated without iir hardware",
  "fix_evidence": "findings/poc/DF-4172/fix.diff (git apply --check clean)"
}