# DF-2031 PoC — Resource leak on IRQ alloc failure in mfi_pci_attach

## Preconditions

1. Root (devctl/kldload require privilege)
2. SYS_RES_IRQ allocation fails — achievable via IRQ exhaustion, MSI
   allocation race, or kernel failpoint

## Trigger

```sh
# Force repeated failed attaches while IRQ cannot be granted:
while true; do
    devctl attach mfi0 2>/dev/null
    sleep 0.1
done
```

## Expected output

- `vmstat -z` shows monotonic growth of bus_dma_tag / resource zones
- `pciconf -lv` / `dmesg` shows MSI vectors reported allocated keep
  climbing
- New device attaches on unrelated drivers start failing with
  "Cannot allocate interrupt" / "Cannot allocate DMA tag"

The leak is bounded only by reboot; it does not recover on its own.

## Success criterion

Monotonic, unbounded growth of leaked DMA-tag/MSI-resource counts that do
not recover until reboot, proving the attach-failure path never released
them. Fixing the bug (`goto out` instead of `return(EINVAL)`) makes the
counts stable across failed attaches.