# TensorRT / onnx-tensorrt PoC: Loop body input OOB (crash)

This repo contains a small malformed ONNX model that triggers a deterministic crash in **onnx-tensorrt**'s `Loop` importer.

## Summary

The ONNX `Loop` operator has a `body` subgraph.

`onnx-tensorrt` assumes that the number of inputs in the loop body subgraph is **at least** the number of inputs on the outer `Loop` node.

If a malicious ONNX model provides a `Loop` node with **3 inputs** (trip-count, condition, state0) but the `body` graph contains only **2 inputs**, the parser indexes `body.input(2)` out-of-bounds while mapping state variables.

## Files

- `poc_loop_body_input_oob.onnx` – malformed ONNX model
- `make_poc_loop_body_input_oob.py` – generator script (does not require the `onnx` pip package)
- `gen/onnx_pb2.py` – protobuf bindings generated from `onnx.proto`

## Reproduction (typical TensorRT install)

### Using `trtexec`

```bash
trtexec --onnx=poc_loop_body_input_oob.onnx --verbose
```

Expected result: **process crash / abort** during ONNX parse or network build.

### Using the C++ API

Any code path that calls the TensorRT ONNX parser on this model should reproduce, e.g. `nvonnxparser::IParser::parseFromFile()`.

## Regenerating the model

```bash
# Requires: python3 + protobuf runtime, and a generated onnx_pb2 (already included in gen/)
python3 make_poc_loop_body_input_oob.py poc_loop_body_input_oob.onnx
```