Null pointer dereference in `MatrixDiagPartOp`

Impact

If a user does not provide a valid padding value to tf.raw_ops.MatrixDiagPartOp, then the code triggers a null pointer dereference (if input is empty) or produces invalid behavior, ignoring all values after the first:

import tensorflow as tf

tf.raw_ops.MatrixDiagPartV2(
  input=tf.ones(2,dtype=tf.int32),
  k=tf.ones(2,dtype=tf.int32),
  padding_value=[])

Although this example is given for MatrixDiagPartV2, all versions of the operation are affected.

The implementation reads the first value from a tensor buffer without first checking that the tensor has values to read from.

Patches

We have patched the issue in GitHub commit 482da92095c4d48f8784b1f00dda4f81c28d2988.

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.