  Neural networks are vulnerable to a wide range of erroneous inputs such as
adversarial, corrupted, out-of-distribution, and misclassified examples. In
this work, we train a linear SVM classifier to detect these four types of
erroneous data using hidden and softmax feature vectors of pre-trained neural
networks. Our results indicate that these faulty data types generally exhibit
linearly separable activation properties from correct examples, giving us the
ability to reject bad inputs with no extra training or overhead. We
experimentally validate our findings across a diverse range of datasets,
domains, pre-trained models, and adversarial attacks.
