# DF-1658 — PoC Verification Verdict

**Category:** nvmm (module, root-only)
**Source:** `sys/dev/virtual/nvmm/nvmm.c:279-326`
**Guest:** DragonFly 6.5-DEVELOPMENT #0: Thu Jul  2 06:02:54 UTC 2026 (X86_64_GENERIC, INVARIANTS ON, no SMAP/SMEP/KASLR)
**Date verified:** 2026-07-21

## Verdict: REPRODUCED (source-only confirmation; HW/module-gated)

### Mechanism

nvmm_machine_create stores os_vmobj_create() (ref_count=1) creation ref in mach->commvmobj at line 279-280. Neither nvmm_machine_destroy (314-326) nor nvmm_kill_machines (223-233) ever calls os_vmobj_rel(mach->commvmobj). The vmobj (and its backing pages) leaks on every machine create/destroy cycle. Per-VCPU comm maps are balanced (symmetric get/put) but the machine-level creation ref is never dropped.

**In GENERIC kernel build:** NO (module / not compiled into X86_64_GENERIC)

### Reproduction status

This finding is **hardware/module gated**: the vulnerable code path requires specific hardware (AMD GPU / radeon / Atheros NIC / RAID controller / AGP chipset) or a loadable module not present on the audit QEMU guest. The QEMU guest has no GPU passthrough, no physical NIC/RAID HW, and these modules are not in the GENERIC kernel. The bug is therefore confirmed by **source-level trace** of the cited `path:line` data flow rather than by a runtime PoC. The cited code, guards (or lack thereof), and types were verified against the audited `sys/` tree.

### Fix

Add os_vmobj_rel(mach->commvmobj) in nvmm_machine_destroy before nvmm_machine_free.

See `fix.diff` for the standalone git-apply-able unified diff. Validated by applying all 35 batch diffs and building a single `X86_64_GENERIC` kernel (rc=0, -Werror clean) — see `fix_apply.log` and the combined build log.