NPE in TFLite

Impact

The implementation of SVDF in TFLite is vulnerable to a null pointer error:

  TfLiteTensor* state = GetVariableInput(context, node, kStateTensor);
  // ...
  GetTensorData<float>(state)

The GetVariableInput function can return a null pointer but GetTensorData assumes that the argument is always a valid tensor.

TfLiteTensor* GetVariableInput(TfLiteContext* context, const TfLiteNode* node,
                               int index) {
  TfLiteTensor* tensor = GetMutableInput(context, node, index);
  return tensor->is_variable ? tensor : nullptr;
}

Furthermore, because GetVariableInput calls GetMutableInput which might return nullptr, the tensor->is_variable expression can also trigger a null pointer exception.

Patches

We have patched the issue in GitHub commit 5b048e87e4e55990dae6b547add4dae59f4e1c76.

The fix will be included in TensorFlow 2.6.0. We will also cherrypick this commit on TensorFlow 2.5.1, TensorFlow 2.4.3, and TensorFlow 2.3.4, as these are also affected and still in supported range.

For more information

Please consult our security guide for more information regarding the security model and how to contact us with issues and questions.

Attribution

This vulnerability has been reported by members of the Aivul Team from Qihoo 360.