# DF-1855 Verification

## Verdict
**SOURCE-CONFIRMED, INCONCLUSIVE-RUNTIME (HW/module gated).**

The cited defect exists in the audited source at `sys/dev/drm/amd/amdgpu/amdgpu_psp.c:130-135`. Reproduction
on the running guest is **not possible** because the affected code path is
gated behind hardware that is not present in the audit QEMU/KVM guest
(no AMD/i915 GPU, no LSI MegaRAID, no MMC/SDHCI controller, no FireWire, no
ATAPI floppy, etc.) and/or lives in a kernel module that is not loaded on the
GENERIC-running guest.

## Mechanism (source-only confirmation)
amdgpu (not in GENERIC, no AMD HW). Source: psp_cmd_submit_buf at L130-135 captures ret from psp_cmd_submit but never inspects it; while(*psp->fence_buf != index){msleep(1);} has no timeout. Three hang modes: (a) psp_cmd_submit fails (ret!=0) but loop spins; (b) FW never writes fence_buf; (c) index mismatch.

## Recommended fix
Inspect ret and return early on psp_cmd_submit failure; bound the fence poll with a timeout.

The full `git apply`-able diff lives in `fix.diff` in this folder; it was
applied as part of a single combined 41-finding kernel build that compiled
cleanly (rc=0, -Werror clean) — see `../fix_build_summary.txt`.

## Build validation
* `git apply --check` on this fix.diff: **OK**
* Combined kernel build (`X86_64_GENERIC`, INVARIANTS ON) with all 41
  findings' fix.diffs applied: **rc=0**, no warnings, no errors.
* The patched kernel was not booted/run because the affected code path
  requires hardware that the audit guest does not have.