# DF-1423 — Verification Verdict

## Verdict: CONFIRMED-BY-SOURCE-TRACE (root-only)

**Status:** inconclusive (HW-gated / not reachable as unprivileged maxx)
**Impact:** none (cannot reproduce on QEMU guest — no GPU/HW, or root/operator-only)
**Confidence:** certain (source-trace confirmed bug is real)

## Mechanism

gdt_ioctl_cmd (:1036): if(cnt+sense_len>GDT_SCRATCH_SZ) — u32+u32 wraps. sdlen=0xFFFFFFFF+sense_len=1 → 0. Passes check. bcopy(ucmd->data,gc_scratch,0xFFFFFFFF) → ~4GB kernel heap OOB write. gc_scratch is 3072B slot. ucmd->data is raw user pointer (no copyin). /dev/iir0 mode 0600 (root only).

**Source:** `sys/dev/raid/iir/iir.c:1036`

## Why it cannot be reproduced on this guest

Root-only. /dev/iir0 is mode 0600 (root only). Also requires IIR RAID controller hardware.

## Phase 6: Escalation Assessment

This is a **Root-only + HW-gated (iir RAID)** finding. The primitive is not reachable from the
unprivileged maxx user on this guest (no hardware / module not loaded / root-only device).
No escalation chain is possible because the trigger path is not exercisable.

For GPU findings: the module (radeon.ko/amdgpu.ko/i915.ko) is a loadable module not
present in the GENERIC kernel and requires actual GPU hardware absent from the QEMU guest.
For root/operator findings: the device node is mode 0600 or 0640 root:operator, and maxx
(uid 1001) has no operator group membership.

## Fix

Check cnt > GDT_SCRATCH_SZ || sense_len > GDT_SCRATCH_SZ - cnt (avoids overflow).

**Fix description:** Rewrite bounds check to avoid u32+u32 overflow: cnt > GDT_SCRATCH_SZ || sense_len > GDT_SCRATCH_SZ - cnt.

The full git-apply-able diff is in `fix.diff`. It applies cleanly to the audit source tree
and compiles as part of the kernel build (validated via `make nativekernel` rc=0).

## Classification

- **status:** inconclusive
- **reproduced:** 0
- **impact:** none
- **fix_status:** not_testable (HW-gated: PoC cannot run on guest; diff applies + compiles verified)