# DF-1826 - Source Verification

## Verdict: REPRODUCED (source-only confirmation)

**Finding**: sys/dev/drm/i915/intel_guc.c:187-190

**Mechanism**: guc_shared_data_destroy frees shared_data VMA but never clears shared_data_vaddr. Consumer wait_for_guc_preempt_report reads dangling vaddr → UAF on freed page.

**Hardware dependency**: Requires i915 GPU with enable_guc>0 (default 0).

**Fix**: Set guc->shared_data_vaddr = NULL in guc_shared_data_destroy.

## 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