{
 "finding_id": "DF-2861",
 "status": "reproduced",
 "reproduced": 1,
 "impact": "none",
 "confidence": "certain",
 "verdict": "Mechanically confirmed via the harness on the stock guest: sglist_consume_uio over an unmapped user VA appended the segment {ss_paddr=0x0, len=16} and returned success - _sglist_append_buf never checks pmap_extract() failure (subr_sglist.c:125-156): an invalid user buffer becomes a physical-page-0 DMA segment instead of EFAULT; a consumer would transfer to/from physical page 0. Only reachable via append_user/append_uio/consume_uio which have zero in-tree callers (dead paths; FreeBSD HEAD likewise unchecked). On the fix kernel the same call returns EFAULT with nseg=0.",
 "exploit_chain": "unmapped user buffer -> pmap_extract returns 0 -> DMA segment pinned at physical page 0",
 "evidence": "harness.log T7: seg0.paddr=0x0 len=16 ret=0; fix kernel: ret=14 nseg=0",
 "kernel_refs": [
  "sys/kern/subr_sglist.c:125",
  "sys/kern/subr_sglist.c:153"
 ],
 "poc_changes": "none",
 "attempts": 1,
 "guest_uname": "DragonFly dfbsd 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": "cd /root/h41 && make",
 "run_cmd": "kldload ./h41.ko; sysctl -w debug.h41.cmd=7",
 "code_hash": "85d6e241caa2a7fb1fb44b80c7736a4e83c36d29314b0c96ce91769bc9bdf839",
 "notes": "Dead paths in-tree; latent for future consumers",
 "recommended_fix": "if (paddr == 0) { pmap_extract_done(handle); return (EFAULT); } at both extract sites",
 "fix_status": "fixed",
 "fix_baseline_reproduced": 1,
 "fix_patched_reproduced": 0,
 "fix_kernel_uname": "DragonFly dfbsd 6.5-DEVELOPMENT #1: Mon Oct 26 01:57:23 UTC 2026 root@dfbsd:/usr/obj/usr/src/sys/X86_64_GENERIC x86_64 (h41 fix kernel, all 41 hardening fixes applied)",
 "fix_verdict": "A/B: baseline paddr=0 segment appended; fix kernel EFAULT before any append (both extract sites)."
}