{
  "finding_id": "DF-3196",
  "status": "untested",
  "reproduced": 0,
  "impact": "none",
  "confidence": "likely",
  "verdict": "Latent defect visible by inspection: nfs_nget_nonblock()s revalidation restart (nfs_node.c:271-273) executes vput(vp) and goto loop without resetting vp, so any execution that takes that branch double-vputs the stale vnode (second vput either at the next matching node or at the :284 cleanup) -> refcount underflow -> premature vnode recycling / vrele assert panic. The branch requires a stale bucket view (preemption of the token-holding scanner inside the restart window plus re-creation of the matching node by a third thread) - the same window class as DF-3194 but narrower; not dynamically triggerable on the QEMU guest within this run (the wider DF-3194 window already failed to fire in ~620k races). The one-line fix (vp = NULL before goto loop, mirroring the :344-348 comments own rule) is included as hunk 3 of DF-3194s fix.diff and was compiled+booted in the DF-3195 validation kernel.",
  "exploit_chain": "",
  "evidence": [
    "findings/poc/DF-3196/README.md (full analysis)",
    "findings/poc/DF-3194/fix.diff hunk 3 (the fix)",
    "sys/vfs/nfs/nfs_node.c:271-273 vs :344-348"
  ],
  "kernel_refs": [
    "sys/vfs/nfs/nfs_node.c:265-278",
    "sys/vfs/nfs/nfs_node.c:271-273",
    "sys/vfs/nfs/nfs_node.c:284-287",
    "sys/vfs/nfs/nfs_node.c:344-348",
    "sys/vfs/nfs/nfs_vnops.c:2891"
  ],
  "poc_changes": "n/a (no standalone PoC; would require the same racing harness as DF-3194 plus readdirplus traffic)",
  "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": 0,
  "guest_dirty": 0,
  "build_cmd": "n/a",
  "run_cmd": "n/a",
  "code_hash": "n/a",
  "notes": "Low severity: narrow preemption-gated race, panic-class sink (refcount underflow), unprivileged trigger surface (concurrent getdents). Fix trivially correct and already compiled in the DF-3195 validation kernel.",
  "recommended_fix": "vp = NULL; before the goto loop at nfs_node.c:273 (hunk 3 of DF-3194s fix.diff).",
  "fix_status": "not_testable",
  "fix_kernel_uname": "",
  "fix_baseline_reproduced": 0,
  "fix_patched_reproduced": 0,
  "fix_verdict": "fix.diff hunk 3 compiled and booted as part of the DF-3195 validation kernel; behavioral comparison impossible (baseline race not triggerable in-guest).",
  "fix_evidence": "findings/poc/DF-3194/fix.diff hunk 3; DF-3195 pack run.fixed.log ran on that kernel."
}