DF-3008 / verdict.json
{ "finding_id": "DF-3008", "status": "not_reproduced", "reproduced": 0, "impact": "none", "confidence": "likely", "verdict": "Attempted on the guest with a 20-second dual-thread hammer (805,155 kern.devname sysctl queries against 21,740,405 ptmx clone open/close cycles). The lifetime race IS crossed constantly - 397,088 queries returned ENOENT because the queried cdev had already been destroyed - but the post-destroy si_name read never returned stale or corrupted data: every successful lookup returned a well-formed device name (ptm/N) because the objcache retains freed chunk contents. The claimed UAF-read is therefore unobservable from userspace, exactly as the original finding predicted (reported for the lifetime-contract gap, not for a demonstrable disclosure).", "exploit_chain": "", "evidence": "VERDICT.md + run.log + sources", "kernel_refs": [ "sys/vfs/devfs/devfs_core.c:1659", "sys/vfs/devfs/devfs_core.c:2771", "sys/vfs/devfs/devfs_core.c:2786" ], "poc_changes": "adjusted from finding sketch to guest syscall/layout reality", "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": 25, "guest_dirty": 0, "build_cmd": "guest: cc -O2 -o <bin> <src>.c -pthread", "run_cmd": "see README.md", "code_hash": "526efb40bd6d1fda013ff59b765a6deb9bf96d325a73bdcd00d76794895a97d3", "notes": "fix_status: not_testable (not reproduced)", "recommended_fix": "diff --git a/sys/vfs/devfs/devfs_core.c b/sys/vfs/devfs/devfs_core.c\nCopy si_name into the reply message in devfs_find_device_by_devid_worker so the sysctl never dereferences the cdev after the devfs lock is released.\n" } |