# DF-1951 Verification

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

The cited defect exists in the audited source at `sys/dev/drm/amd/amdgpu/amdgpu_bios.c:338-357`. 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: amdgpu_atrm_get_bios at L338 adev->bios=kmalloc(size=256KB, M_DRM, GFP_KERNEL=M_WAITOK|M_CACHEALIGN) — NO M_ZERO. L344-351 loop fills only the portion ATRM returns (typically 64-128KB). When VBIOS<256KB, amdgpu_atrm_call returns ret<ATRM_BIOS_PAGE, loop breaks. The unfilled tail contains uninitialized kernel heap, exposed to userspace via /dev/mem or AtomBios parser.

## Recommended fix
memset(adev->bios, 0, size) after the kmalloc (or use M_ZERO).

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.