# DF-1800 — 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/drm/amd/powerplay/hwmgr/smu_helper.c:520-527`.

## Mechanism
phm_get_lowest_enabled_level while(mask&(1<<level)) level++ has no mask==0 check and no upper bound; level>=32 is UB shift. Callers pre-check but latent if future caller omits.

## Fix
Add mask==0 early return.

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 GPU/display 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.