# DF-1949 Verification

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

The cited defect exists in the audited source at `sys/dev/drm/amd/display/dc/basics/fixpt31_32.c:43-67`. 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)
amd display DC (not in GENERIC, no AMD HW). Source: complete_integer_division_u64 at L43-55 guards divisor solely ASSERT(divisor) at L50. Production ASSERT=WARN_ON(!(expr)) in os_types.h:65-77 emits warning but returns without aborting. Then L52 div64_u64_rem(dividend,0,remainder) — raw divide-by-zero in math64.h.

## Recommended fix
Replace ASSERT(divisor) with a real `if (divisor == 0) { ...; return 0; }` guard.

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.