# DF-1655 — PoC Verification Verdict

**Category:** radeon UVD (module, HW-gated)
**Source:** `sys/dev/drm/radeon/radeon_uvd.c:367-368`
**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

radeon_uvd_cs_msg_decode uses plain u32 math: image_size=width*height (line 367). width=height=0x10000 wraps image_size to 0. Then MPEG2 min_dpb_size=image_size*3=0; the dpb_size<min_dpb_size check (431) accepts dpb_size=0. buf_sizes[1]=buf_sizes[2]=0, degenerating subsequent bound checks.

**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

Reject width==0 or height==0 with -EINVAL before computing image_size.

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.