void CommandBufferProxyImpl::TryUpdateState() {
  CheckLock();
  last_state_lock_.AssertAcquired();
  if (last_state_.error == gpu::error::kNoError) {
    shared_state()->Read(&last_state_);
    if (last_state_.error != gpu::error::kNoError)
      OnGpuStateError();
  }
}

The product writes data past the end, or before the beginning, of the intended buffer.