#!/bin/sh
# DF-1319 — no userspace PoC is runnable on the QEMU audit guest.
#
# The bug lives in amdgpu's DisplayPort link-training path, triggered by a
# malicious DP sink (dongle / MST hub / monitor) reporting an out-of-range
# lane_count in DPCD 0x220 on hotplug -> HPD IRQ -> handle_automated_test ->
# dp_test_send_link_training.  amdgpu is NOT compiled into X86_64_GENERIC,
# is NOT a loadable module on this guest, and there is NO AMD GPU hardware
# in QEMU.  Reproduction requires: (a) a host with an AMD GPU running
# amdgpu, and (b) a malicious DP peripheral (or a USB-C DP attacker
# device) under attacker control.  See VERDICT.md for the full line-by-line
# trace.
#
# This script instead documents the SOURCE-LEVEL fix build check:
#   cd /usr/src && patch -p1 < fix.diff && make nativekernel ...
# The fix.diff was validated to apply cleanly (git apply --check) against
# sys/dev/drm/amd/display/dc/core/dc_link_dp.c.  amdgpu is not in the
# X86_64_GENERIC kernel, so a nativekernel build does NOT exercise this
# translation unit; the diff is compile-validated only at the apply stage.
echo "DF-1319: no runnable userspace PoC on this guest (no AMD GPU / amdgpu)."
echo "See VERDICT.md for the source trace and fix.diff for the patch."
echo "Validating fix.diff applies cleanly:"
git apply --check -p1 fix.diff && echo "APPLIES_CLEAN" || echo "apply-check FAILED"