Vulnerability: Division by 0 in `QuantizedMul` ### Impact
An attacker can trigger a division by 0 in `tf.raw_ops.QuantizedMul`:

```python
import tensorflow as tf

x = tf.zeros([4, 1], dtype=tf.quint8)
y = tf.constant([], dtype=tf.quint8)
min_x = tf.constant(0.0)
max_x = tf.constant(0.0010000000474974513)
min_y = tf.constant(0.0)
max_y = tf.constant(0.0010000000474974513)

tf.raw_ops.QuantizedMul(x=x, y=y, min_x=min_x, max_x=max_x, min_y=min_y, max_y=max_y)
```                            

This is because the [implementation](https://github.com/tensorflow/tensorflow/blob/55900e961ed4a23b438392024912154a2c2f5e85/tensorflow/core/kernels/quantized_mul_op.cc#L188-L198) does a division by a quantity that is controlled by the caller:

```cc
template <class T, class Toutput>
void VectorTensorMultiply(const T* vector_data, int32 vector_offset,
                          int64 vector_num_elements, const T* tensor_data,
                          int32 tensor_offset, int64 tensor_num_elements,
                          Toutput* output) {
  for (int i = 0; i < tensor_num_elements; ++i) {
    const int64 vector_i = i % vector_num_elements;
    ...
  }
}
```

### Patches
We have patched the issue in GitHub commit [a1b11d2fdd1e51bfe18bb1ede804f60abfa92da6](https://github.com/tensorflow/tensorflow/commit/a1b11d2fdd1e51bfe18bb1ede804f60abfa92da6).

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 Ying Wang and Yakun Zhang of Baidu X-Team.
Vulnerability ID: GHSA-6f84-42vf-ppwp
CWE: CWE-369
Severity score: 2.5
Project: https://github.com/tensorflow/tensorflow
Published: 2021-05-21
File: tensorflow/core/kernels/quantized_mul_op.cc
Commit message: Fix one division by zero

PiperOrigin-RevId: 369474832
Change-Id: I1082858ed78d9b2e4738ce30b231955973d49e1e
Commit author: Mihai Maruseac

Vulnerable version (before fix):
 class QuantizedMulOp : public OpKernel {         tensor_num_elements = x.NumElements();         tensor_offset = offset_x;       }       VectorTensorMultiply<T, Toutput>(           vector_data, vector_offset, vector_num_elements, tensor_data,           tensor_offset, tensor_num_elements, z_data);

Fixed version (after fix):
 class QuantizedMulOp : public OpKernel {         tensor_num_elements = x.NumElements();         tensor_offset = offset_x;       }       if (vector_num_elements == 0) {         context->SetStatus(             errors::InvalidArgument("vector must have at least 1 element"));         return;       }       VectorTensorMultiply<T, Toutput>(           vector_data, vector_offset, vector_num_elements, tensor_data,           tensor_offset, tensor_num_elements, z_data);

Patch:
patch: @@ -347,6 +347,11 @@ class QuantizedMulOp : public OpKernel {
         tensor_num_elements = x.NumElements();
         tensor_offset = offset_x;
       }
+      if (vector_num_elements == 0) {
+        context->SetStatus(
+            errors::InvalidArgument("vector must have at least 1 element"));
+        return;
+      }
       VectorTensorMultiply<T, Toutput>(
           vector_data, vector_offset, vector_num_elements, tensor_data,
           tensor_offset, tensor_num_elements, z_data);
path: tensorflow/core/kernels/quantized_mul_op.cc