Division by zero in TFLite's implementation of `SVDF`
### Impact
The implementation of the `SVDF` TFLite operator is vulnerable to a division by zero error
https://github.com/tensorflow/tensorflow/blob/7f283ff806b2031f407db64c4d3edcda8fb9f9f5/tensorflow/lite/kernels/svdf.cc#L99-L102:
```cc
const int rank = params->rank;
...
TF_LITE_ENSURE_EQ(context, num_filters % rank, 0);
```
An attacker can craft a model such that `params->rank` would be 0.
### Patches
We have patched the issue in GitHub commit 6841e522a3e7d48706a02e8819836e809f738682
https://github.com/tensorflow/tensorflow/commit/6841e522a3e7d48706a02e8819836e809f738682.
The fix will be included in TensorFlow 2.5.0. We will also cherrypick this commit on TensorFlow 2.4.2, TensorFlow 2.3.3, TensorFlow 2.2.3 and TensorFlow 2.1.4, 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 by members of the Aivul Team from Qihoo 360.