CVE-2021-37647

Tensorflow-gpu 2.3.4, 2.4.3, 2.5.1 and 2.6.0 include a fix for CVE-2021-37647: When a user does not supply arguments that determine a valid sparse tensor, 'tf.raw_ops.SparseTensorSliceDataset' implementation can be made to dereference a null pointer. The implementation (https://github.com/tensorflow/tensorflow/blob/8d72537c6abf5a44103b57b9c2e22c14f5f49698/tensorflow/core/kernels/data/sparse_tensor_slice_dataset_op.cc#L240-L251) has some argument validation but fails to consider the case when either 'indices' or 'values' are provided for an empty sparse tensor when the other is not. If 'indices' is empty, then code that performs validation (https://github.com/tensorflow/tensorflow/blob/8d72537c6abf5a44103b57b9c2e22c14f5f49698/tensorflow/core/kernels/data/sparse_tensor_slice_dataset_op.cc#L260-L261) (i.e., checking that the indices are monotonically increasing) results in a null pointer dereference. If 'indices' as provided by the user is empty, then 'indices' in the C++ code above is backed by an empty 'std::vector', hence calling 'indices->dim_size(0)' results in null pointer dereferencing (same as calling 'std::vector::at()' on an empty vector). The Tensorflow team has patched the issue in GitHub commit 02cc160e29d20631de3859c6653184e3f876b9d7.