Vulnerability: Division by 0 in `QuantizedBiasAdd` ### Impact
An attacker can trigger an integer division by zero undefined behavior in `tf.raw_ops.QuantizedBiasAdd`:

```python
import tensorflow as tf

input_tensor = tf.constant([], shape=[0, 0, 0, 0], dtype=tf.quint8)
bias = tf.constant([], shape=[0], dtype=tf.quint8)
min_input = tf.constant(-10.0, dtype=tf.float32)
max_input = tf.constant(-10.0, dtype=tf.float32)
min_bias = tf.constant(-10.0, dtype=tf.float32)
max_bias = tf.constant(-10.0, dtype=tf.float32)

tf.raw_ops.QuantizedBiasAdd(input=input_tensor, bias=bias, min_input=min_input,
                            max_input=max_input, min_bias=min_bias,
                            max_bias=max_bias, out_type=tf.qint32)
```

This is because the [implementation of the Eigen kernel](https://github.com/tensorflow/tensorflow/blob/61bca8bd5ba8a68b2d97435ddfafcdf2b85672cd/tensorflow/core/kernels/quantization_utils.h#L812-L849) does a division by the number of elements of the smaller input (based on shape) without checking that this is not zero:

```cc
template <typename T1, typename T2, typename T3>
void QuantizedAddUsingEigen(const Eigen::ThreadPoolDevice& device,
                            const Tensor& input, float input_min,
                            float input_max, const Tensor& smaller_input,
                            float smaller_input_min, float smaller_input_max,
                            Tensor* output, float* output_min,
                            float* output_max) {
  ...
  const int64 input_element_count = input.NumElements();
  const int64 smaller_input_element_count = smaller_input.NumElements();
  ...
  bcast[0] = input_element_count / smaller_input_element_count;
  ...
}
```

This integral division by 0 is undefined behavior.

### Patches
We have patched the issue in GitHub commit [67784700869470d65d5f2ef20aeb5e97c31673cb](https://github.com/tensorflow/tensorflow/commit/67784700869470d65d5f2ef20aeb5e97c31673cb).

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 Yakun Zhang and Ying Wang of Baidu X-Team.
Vulnerability ID: GHSA-m34j-p8rj-wjxq
CWE: CWE-369
Severity score: 2.5
Project: https://github.com/tensorflow/tensorflow
Published: 2021-05-21
File: tensorflow/core/kernels/quantized_bias_add_op.cc
Commit message: Prevent division by 0 in `QuantizedBiasAdd`.

PiperOrigin-RevId: 370117454
Change-Id: I3804e2ac8dcc6d3afcc92e27853e2325a017ca4d
Commit author: Mihai Maruseac

Vulnerable version (before fix):
 class QuantizedBiasAddOp : public OpKernel {             "Must provide as many biases as the last dimension "             "of the input tensor: ",             bias.shape().DebugString(), " vs. ", input.shape().DebugString()));      Tensor* output = nullptr;     OP_REQUIRES_OK(context,

Fixed version (after fix):
 class QuantizedBiasAddOp : public OpKernel {             "Must provide as many biases as the last dimension "             "of the input tensor: ",             bias.shape().DebugString(), " vs. ", input.shape().DebugString()));     OP_REQUIRES(context, bias.NumElements() > 0,                 errors::InvalidArgument("Must provide at least 1 bias"));      Tensor* output = nullptr;     OP_REQUIRES_OK(context,

Patch:
patch: @@ -56,6 +56,8 @@ class QuantizedBiasAddOp : public OpKernel {
             "Must provide as many biases as the last dimension "
             "of the input tensor: ",
             bias.shape().DebugString(), " vs. ", input.shape().DebugString()));
+    OP_REQUIRES(context, bias.NumElements() > 0,
+                errors::InvalidArgument("Must provide at least 1 bias"));
 
     Tensor* output = nullptr;
     OP_REQUIRES_OK(context,
path: tensorflow/core/kernels/quantized_bias_add_op.cc