CVE-2021-29546: Division by 0 in `QuantizedBiasAdd`
First published: Fri May 14 2021(Updated: )
### 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.
Credit: security-advisories@github.com security-advisories@github.com
| Affected Software | Affected Version | How to fix |
|---|---|---|
| pip/tensorflow-gpu | >=2.4.0<2.4.2 | 2.4.2 |
| pip/tensorflow-gpu | >=2.3.0<2.3.3 | 2.3.3 |
| pip/tensorflow-gpu | >=2.2.0<2.2.3 | 2.2.3 |
| pip/tensorflow-gpu | <2.1.4 | 2.1.4 |
| pip/tensorflow-cpu | >=2.4.0<2.4.2 | 2.4.2 |
| pip/tensorflow-cpu | >=2.3.0<2.3.3 | 2.3.3 |
| pip/tensorflow-cpu | >=2.2.0<2.2.3 | 2.2.3 |
| pip/tensorflow-cpu | <2.1.4 | 2.1.4 |
| pip/tensorflow | >=2.4.0<2.4.2 | 2.4.2 |
| pip/tensorflow | >=2.3.0<2.3.3 | 2.3.3 |
| pip/tensorflow | >=2.2.0<2.2.3 | 2.2.3 |
| pip/tensorflow | <2.1.4 | 2.1.4 |
| TensorFlow Keras | <2.1.4 | |
| TensorFlow Keras | >=2.2.0<2.2.3 | |
| TensorFlow Keras | >=2.3.0<2.3.3 | |
| TensorFlow Keras | >=2.4.0<2.4.2 |
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Reference Links
- https://github.com/tensorflow/tensorflow/commit/67784700869470d65d5f2ef20aeb5e97c31673cb
- https://github.com/tensorflow/tensorflow/security/advisories/GHSA-m34j-p8rj-wjxq
- https://nvd.nist.gov/vuln/detail/CVE-2021-29546
- https://github.com/pypa/advisory-database/tree/main/vulns/tensorflow-cpu/PYSEC-2021-474.yaml
- https://github.com/pypa/advisory-database/tree/main/vulns/tensorflow-gpu/PYSEC-2021-672.yaml
- https://github.com/pypa/advisory-database/tree/main/vulns/tensorflow/PYSEC-2021-183.yaml
- https://github.com/advisories/GHSA-m34j-p8rj-wjxq (Advisory)
Frequently Asked Questions
What is the severity of CVE-2021-29546?
The severity of CVE-2021-29546 is classified as high due to the potential for integer division by zero leading to undefined behavior.
How do I fix CVE-2021-29546?
To fix CVE-2021-29546, upgrade TensorFlow to versions 2.1.4, 2.2.3, 2.3.3, or 2.4.2.
Which versions of TensorFlow are affected by CVE-2021-29546?
CVE-2021-29546 affects TensorFlow versions prior to 2.1.4 and between 2.2.0 and 2.4.2.
Can CVE-2021-29546 be exploited by a remote attacker?
Yes, CVE-2021-29546 can potentially be exploited remotely if an attacker can manipulate the input to `tf.raw_ops.QuantizedBiasAdd`.
What are the symptoms of an application affected by CVE-2021-29546?
Applications affected by CVE-2021-29546 may experience crashes or unexpected behavior when processing certain tensors.
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