Use of unitialized value in TFLite
### Impact
All TFLite operations that use quantization can be made to use unitialized values. For example
https://github.com/tensorflow/tensorflow/blob/460e000de3a83278fb00b61a16d161b1964f15f4/tensorflow/lite/kernels/depthwise_conv.cc#L198-L200:
```cc
const auto* affine_quantization =
reinterpret_cast<TfLiteAffineQuantization*>(
filter->quantization.params);
```
The issue stems from the fact that `quantization.params` is only valid if `quantization.type` is different that `kTfLiteNoQuantization`. However, these checks are missing in large parts of the code.
### Patches
We have patched the issue in GitHub commits 537bc7c723439b9194a358f64d871dd326c18887
https://github.com/tensorflow/tensorflow/commit/537bc7c723439b9194a358f64d871dd326c18887,
4a91f2069f7145aab6ba2d8cfe41be8a110c18a5
https://github.com/tensorflow/tensorflow/commit/4a91f2069f7145aab6ba2d8cfe41be8a110c18a5 and 8933b8a21280696ab119b63263babdb54c298538
https://github.com/tensorflow/tensorflow/commit/8933b8a21280696ab119b63263babdb54c298538.
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
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.