Commit message: Fix heap OOB in `tf.raw_ops.RaggedGather`

PiperOrigin-RevId: 388355464
Change-Id: If14d96231d1cd7aad7c4d1c22c1bab1576b75717
CVE: CVE-2021-37641
CWE: CWE-369
Vulnerability description: TensorFlow is an end-to-end open source platform for machine learning. In affected versions if the arguments to `tf.raw_ops.RaggedGather` don't determine a valid ragged tensor code can trigger a read from outside of bounds of heap allocated buffers. The [implementation](https://github.com/tensorflow/tensorflow/blob/8d72537c6abf5a44103b57b9c2e22c14f5f49698/tensorflow/core/kernels/ragged_gather_op.cc#L70) directly reads the first dimension of a tensor shape before checking that said tensor has rank of at least 1 (i.e., it is not a scalar). Furthermore, the implementation does not check that the list given by `params_nested_splits` is not an empty list of tensors. We have patched the issue in GitHub commit a2b743f6017d7b97af1fe49087ae15f0ac634373. The fix will be included in TensorFlow 2.6.0. We will also cherrypick this commit on TensorFlow 2.5.1, TensorFlow 2.4.3, and TensorFlow 2.3.4, as these are also affected and still in supported range.

Project: tensorflow
File: ragged_gather_op.cc

  void Compute(OpKernelContext* context) override {
    // Get the input Tensors.
    OpInputList params_nested_splits_in;
    OP_REQUIRES_OK(context, context->input_list("params_nested_splits",
                                                &params_nested_splits_in));
    const Tensor& params_dense_values_in =
        context->input(params_nested_splits_in.size());
    const Tensor& indices_in =
        context->input(params_nested_splits_in.size() + 1);

    DCHECK_GT(params_nested_splits_in.size(), 0);  // Enforced by REGISTER_OP.
    SPLITS_TYPE num_params = params_nested_splits_in[0].dim_size(0) - 1;
    OP_REQUIRES_OK(context, ValidateIndices(indices_in, num_params));

    OP_REQUIRES(context, params_dense_values_in.dims() > 0,
                errors::InvalidArgument("params.rank must be nonzero"));
    SPLITS_TYPE num_params_dense_values = params_dense_values_in.dim_size(0);

    // Calculate the `splits`, and store the value slices that we need to
    // copy in `value_slices`.
    std::vector<std::pair<SPLITS_TYPE, SPLITS_TYPE>> value_slices;
    SPLITS_TYPE num_values = 0;
    std::vector<std::vector<SPLITS_TYPE>> out_splits;
    OP_REQUIRES_OK(context, MakeSplits(indices_in, params_nested_splits_in,
                                       num_params_dense_values, &out_splits,
                                       &value_slices, &num_values));

    // Write the output tensors.
    OP_REQUIRES_OK(context, WriteSplits(out_splits, context));
    OP_REQUIRES_OK(context,
                   WriteValues(params_dense_values_in, value_slices,
                               out_splits.size(), num_values, context));
  }

Project: tensorflow
File: ragged_gather_op.cc

  void Compute(OpKernelContext* context) override {
    // Get the input Tensors.

    OpInputList params_nested_splits_in;
    OP_REQUIRES_OK(context, context->input_list("params_nested_splits",
                                                &params_nested_splits_in));
    OP_REQUIRES(
        context, params_nested_splits_in.size() > 0,
        errors::InvalidArgument("params_nested_splits must be non empty"));

    const Tensor& params_dense_values_in =
        context->input(params_nested_splits_in.size());
    const Tensor& indices_in =
        context->input(params_nested_splits_in.size() + 1);

    OP_REQUIRES(context, params_nested_splits_in[0].dims() > 0,
                errors::InvalidArgument("Split tensors must not be scalars"));
    SPLITS_TYPE num_params = params_nested_splits_in[0].dim_size(0) - 1;
    OP_REQUIRES_OK(context, ValidateIndices(indices_in, num_params));

    OP_REQUIRES(context, params_dense_values_in.dims() > 0,
                errors::InvalidArgument("params.rank must be nonzero"));
    SPLITS_TYPE num_params_dense_values = params_dense_values_in.dim_size(0);

    // Calculate the `splits`, and store the value slices that we need to
    // copy in `value_slices`.
    std::vector<std::pair<SPLITS_TYPE, SPLITS_TYPE>> value_slices;
    SPLITS_TYPE num_values = 0;
    std::vector<std::vector<SPLITS_TYPE>> out_splits;
    OP_REQUIRES_OK(context, MakeSplits(indices_in, params_nested_splits_in,
                                       num_params_dense_values, &out_splits,
                                       &value_slices, &num_values));

    // Write the output tensors.
    OP_REQUIRES_OK(context, WriteSplits(out_splits, context));
    OP_REQUIRES_OK(context,
                   WriteValues(params_dense_values_in, value_slices,
                               out_splits.size(), num_values, context));
  }