Vulnerability: Denial of service in `tf.ragged.constant` due to lack of validation ### Impact
The implementation of [`tf.ragged.constant`](https://github.com/tensorflow/tensorflow/blob/f3b9bf4c3c0597563b289c0512e98d4ce81f886e/tensorflow/python/ops/ragged/ragged_factory_ops.py#L146-L239) does not fully validate the input arguments. This results in a denial of service by consuming all available memory:

```python
import tensorflow as tf
tf.ragged.constant(pylist=[],ragged_rank=8968073515812833920)
```
  
### Patches
We have patched the issue in GitHub commit [bd4d5583ff9c8df26d47a23e508208844297310e](https://github.com/tensorflow/tensorflow/commit/bd4d5583ff9c8df26d47a23e508208844297310e).

The fix will be included in TensorFlow 2.9.0. We will also cherrypick this commit on TensorFlow 2.8.1, TensorFlow 2.7.2, and TensorFlow 2.6.4, as these are also affected and still in supported range.

### For more information
Please consult [our security guide](https://github.com/tensorflow/tensorflow/blob/master/SECURITY.md) for more information regarding the security model and how to contact us with issues and questions.

### Attribution
This vulnerability has been reported externally via a [GitHub issue](https://github.com/tensorflow/tensorflow/issues/55199).
Vulnerability ID: GHSA-cwpm-f78v-7m5c
CWE: CWE-20
Severity score: 5.5
Project: https://github.com/tensorflow/tensorflow
Published: 2022-05-24
File: tensorflow/python/ops/ragged/ragged_factory_ops.py
Commit message: Prevent denial of service in `tf.ragged.constant`

Fixes #55199

PiperOrigin-RevId: 442029525
Commit author: Mihai Maruseac

Vulnerable version (before fix):
 def _constant_value(ragged_factory, inner_factory, pylist, dtype, ragged_rank,     if max_depth > scalar_depth:       raise ValueError("Invalid pylist=%r: empty list nesting is greater "                        "than scalar value nesting" % pylist)    # If both inner_shape and ragged_rank were specified, then check that   # they are compatible with pylist.

Fixed version (after fix):
 def _constant_value(ragged_factory, inner_factory, pylist, dtype, ragged_rank,     if max_depth > scalar_depth:       raise ValueError("Invalid pylist=%r: empty list nesting is greater "                        "than scalar value nesting" % pylist)     if ragged_rank is not None and max_depth < ragged_rank:       raise ValueError(f"Invalid pylist={pylist}, max depth smaller than "                        f"ragged_rank={ragged_rank}")    # If both inner_shape and ragged_rank were specified, then check that   # they are compatible with pylist.

Patch:
patch: @@ -188,6 +188,9 @@ def _constant_value(ragged_factory, inner_factory, pylist, dtype, ragged_rank,
     if max_depth > scalar_depth:
       raise ValueError("Invalid pylist=%r: empty list nesting is greater "
                        "than scalar value nesting" % pylist)
+    if ragged_rank is not None and max_depth < ragged_rank:
+      raise ValueError(f"Invalid pylist={pylist}, max depth smaller than "
+                       f"ragged_rank={ragged_rank}")
 
   # If both inner_shape and ragged_rank were specified, then check that
   # they are compatible with pylist.
path: tensorflow/python/ops/ragged/ragged_factory_ops.py