# DF-3090 verification

Kernel: 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

Line-verified confusion exercised as root with the guest hammer2 root mount: nfssvc(NFSSVC_MNTD, {"/"}) and nfssvc(NFSSVC_MNTD|NFSSVC_GOTAUTH, ...) both return 0 cleanly - the type-confused reads of hammer2 mount data through struct nfsmount field offsets happen (nmp = VFSTONFS(vp->v_mount) with only a VROOT check, nfs_syscalls.c:175-176), but the garbage field values route execution into benign early exits (the NFSSTA_MNTD early-return at :180 for the plain call; an authstr NULL path for GOTAUTH) on this filesystem layout. No crash, no observable disclosure, no wild write manifested. Missing vfstype validation is real; impact not demonstrable on this guest.

## Kernel references
- sys/vfs/nfs/nfs_syscalls.c:175
- sys/vfs/nfs/nfs_syscalls.c:180
- sys/vfs/nfs/nfs_kerb.c:70

## Fix
See fix.diff.

## Fix status (batch validation)
Applied with the 36 sibling fix.diffs of this batch in findings/poc/_batch41/all_fixes.patch; single in-guest `make -j6 nativekernel KERNCONF=X86_64_GENERIC` completed RC=0 with zero errors under -Werror (full log: findings/poc/_batch41/fix_build8.log). Behavior A/B intentionally skipped for this Info-tier item.