# DF-1967 - Source Verification

## Verdict: REPRODUCED (source-only confirmation)

**Finding**: sys/dev/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c:346-348

**Mechanism**: dm_dp_add_mst_connector assigns mst_encoder from dm_dp_create_fake_mst_encoder without NULL check, then passes &mst_encoder->base to drm_connector_attach_encoder. OOM → NULL page fault.

**Hardware dependency**: Requires AMD GPU with DisplayPort MST topology.

**Fix**: Add NULL check on mst_encoder; cleanup and return on failure.

## Verification method
Source-only confirmation. The cited code path was traced line-by-line in the
audited sys/ tree. The bug exists exactly as described. This is a HW-gated
driver finding — the vulnerable code path requires specific hardware (GPU,
controller, PHY, TPM, etc.) not present in the QEMU audit guest. Runtime
reproduction on this guest is not possible without the hardware.

## Fix validation
fix.diff authored and applied to guest source. All 40 fixes in this batch
compile cleanly in a single combined kernel build: `make -j6 nativekernel
KERNCONF=X86_64_GENERIC` → rc=0, zero -Werror violations.

**Kernel**: DragonFly 6.5-DEVELOPMENT #0: Thu Jul  2 06:02:54 UTC 2026