# DF-1700 — 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/disk/vn/vn.c:560`.

## Mechanism
vniocattach_file computes sc_size=vio->vn_size*PAGE_SIZE/sc_secsize with no upper bound on vn_size before the int64_t multiply; near INT64_MAX/PAGE_SIZE the multiply overflows producing garbage geometry fed to disk_setdiskinfo_sync.

## Fix
Add upper-bound check: reject vn_size > INT64_MAX/PAGE_SIZE before multiplication.

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.