Heap buffer overflow in `SparseTensorToCSRSparseMatrix`

### Impact An attacker can trigger a denial of service via a `CHECK`-fail in converting sparse tensors to CSR Sparse matrices: ```python import tensorflow as tf import numpy as np from tensorflow.python.ops.linalg.sparse import sparse_csr_matrix_ops indices_array = np.array([[0, 0]]) value_array = np.array([0.0], dtype=np.float32) dense_shape = [0, 0] st = tf.SparseTensor(indices_array, value_array, dense_shape) values_tensor = sparse_csr_matrix_ops.sparse_tensor_to_csr_sparse_matrix( st.indices, st.values, st.dense_shape) ``` This is because the [implementation](https://github.com/tensorflow/tensorflow/blob/800346f2c03a27e182dd4fba48295f65e7790739/tensorflow/core/kernels/sparse/kernels.cc#L66) does a double redirection to access an element of an array allocated on the heap: ```cc csr_row_ptr(indices(i, 0) + 1) += 1; ``` If the value at `indices(i, 0)` is such that `indices(i, 0) + 1` is outside the bounds of `csr_row_ptr`, this results in writing outside of bounds of heap allocated data. ### Patches We have patched the issue in GitHub commit [1e922ccdf6bf46a3a52641f99fd47d54c1decd13](https://github.com/tensorflow/tensorflow/commit/1e922ccdf6bf46a3a52641f99fd47d54c1decd13). 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.

CVSS 3.1

CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L

Severity from

GitHub (reviewed advisory)

Weakness

CWE-131

Also known as

BIT-tensorflow-2021-29545, CVE-2021-29545, PYSEC-2021-182, PYSEC-2021-473, PYSEC-2021-671

• github.com/tensorflow/tensorflow/security/advisories/GHSA-hmg3-c7xj-6qwm
• nvd.nist.gov/vuln/detail/CVE-2021-29545
• github.com/tensorflow/tensorflow/commit/1e922ccdf6bf46a3a52641f99fd47d54c1decd13
• github.com/pypa/advisory-database/tree/main/vulns/tensorflow-cpu/PYSEC-2021-473.yaml
• github.com/pypa/advisory-database/tree/main/vulns/tensorflow-gpu/PYSEC-2021-671.yaml
• github.com/pypa/advisory-database/tree/main/vulns/tensorflow/PYSEC-2021-182.yaml
• github.com/tensorflow/tensorflow