{
  "finding_id": "DF-4197",
  "file": "sys/dev/drm/drm_vblank.c",
  "title": "DragonFly seqlock shim returns the seqcount to its pre-write value -> torn vblank {count,time} snapshots accepted by drm_vblank_count_and_time",
  "verdict": "inconclusive (kernel manifestation hardware-gated; shim defect proven deterministically + under stress)",
  "impact": "none",
  "confidence": "certain",
  "reproduce": {
    "build": "cc -O2 -Wall -pthread -o seqlock_aba seqlock_aba.c",
    "run": "./seqlock_aba demo ; ./seqlock_aba demo_fixed ; ./seqlock_aba stress ; ./seqlock_aba stress_fixed",
    "expected": "demo: TORN PAIR ACCEPTED rc=1; demo_fixed: rejected rc=0; stress: torn_accepted=4057/4189 rc=1; stress_fixed: torn_accepted=0 rc=0"
  },
  "kernel_refs": ["sys/dev/drm/include/linux/seqlock.h:77", "sys/dev/drm/include/linux/seqlock.h:90", "sys/dev/drm/drm_vblank.c:784", "sys/dev/drm/drm_vblank.c:102"],
  "artifacts": ["README.md", "VERDICT.md", "seqlock_aba.c", "build.sh", "run.sh", "build.log", "run.log", "env.txt", "fix.diff", "manifest.json", "verdict.json"]
}