# DF-1706 — Verdict

**Severity:** Low
**Status:** REPRODUCED (source-only confirmation — driver/HW-gated, not runtime-triggered on QEMU guest)
**Impact:** panic
**Confidence:** certain

## Verdict
REPRODUCED. The cited bug is confirmed real in the audited source at `sys/dev/virtual/virtio/balloon/virtio_balloon.c:551,868`.

## Mechanism
vtballoon_update_stats asserts ASSERT_SERIALIZED but the sole live caller (vtballoon_thread:868) invokes without acquiring the serializer. Dormant (priming disabled) but would corrupt vq state or panic on INVARIANTS if re-enabled.

## Fix
Acquire VTBALLOON_SLZ around vtballoon_update_stats call in the thread.

The full git-apply-able diff is in `fix.diff`.

## Build validation
fix.diff applies cleanly and compiles with `-Werror` as part of the batch module build
(all 51 fixes applied to /usr/src, kernel+modules built).

## Notes
Source-only confirmation: this finding is in a device driver code path that requires
specific hardware not present in the QEMU guest. The bug is confirmed by source tracing
(cited path:line verified against sys/), and the fix compiles clean. No runtime trigger
was attempted as the relevant device/module is HW-gated.