{
 "finding_id": "DF-4746",
 "status": "not_reproduced",
 "reproduced": 0,
 "impact": "none",
 "confidence": "certain",
 "verdict": "Line-accurate confirmation; runtime demonstration not possible on this guest (no LANCE/PCnet NIC in QEMU; the lnc driver is compiled into X86_64_GENERIC as device lnc0 but never attaches). lance_put (lance.c:309-326) walks the whole chain copying m->m_len at advancing offsets into a fixed LEBLEN(1522)-byte TX slot with no total bound; am79900.c:560 / am7990.c:523 feed it directly from ifq_dequeue. Unprivileged reachability is closed today (ether_ioctl caps MTU at ETHERMTU; remaining vector is root-only BPF writes). Fix adds a pkthdr.len > LEBLEN - ETHER_CRC_LEN drop guard at both dequeue sites; both files compiled in the F40FIX build (lnc in kernel).",
 "exploit_chain": "",
 "evidence": "VERDICT.md with path:line citations; run.log where a live demo exists; fix.diff",
 "kernel_refs": [
  "sys/dev/netif/lnc/am79900.c:560",
  "sys/dev/netif/lnc/lance.c:309",
  "sys/dev/netif/lnc/lancereg.h:132"
 ],
 "poc_changes": "n/a - no lnc hardware in QEMU",
 "attempts": 0,
 "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": 30,
 "guest_dirty": 0,
 "build_cmd": "see build.sh",
 "run_cmd": "see run.sh",
 "code_hash": null,
 "notes": "",
 "recommended_fix": "drop chains with pkthdr.len > LEBLEN - ETHER_CRC_LEN before lance_put (am79900 + am7990)",
 "fix_status": "compile_validated",
 "fix_verdict": "fix.diff applied in the F40FIX verification kernel build (RC=0, zero -Werror errors); no runtime A/B for this item (line-certain hardening)"
}