[Security] Add a check for empty variant tensor input to CompositeTen…

…sorVariantToComponents.

So an exception will be raised instead of segfault.

PiperOrigin-RevId: 474397914

tensorflow/core/kernels/composite_tensor_ops.cc

@@ -15,6 +15,7 @@ limitations under the License.
 
 #include "tensorflow/core/framework/op.h"
 #include "tensorflow/core/framework/op_kernel.h"
+#include "tensorflow/core/framework/op_requires.h"
 #include "tensorflow/core/framework/variant.h"
 #include "tensorflow/core/framework/variant_encode_decode.h"
 #include "tensorflow/core/kernels/composite_tensor_variant.h"
@@ -66,6 +67,11 @@ class CompositeTensorVariantToComponents : public OpKernel {
 
   void Compute(OpKernelContext* context) override {
     Tensor encoded_t = context->input(0);
+    OP_REQUIRES(
+        context, encoded_t.flat<Variant>().size() > 0,
+        errors::InvalidArgument("Input `encoded` must not be an empty variant "
+                                "tensor, but got ",
+                                encoded_t.DebugString()));
     auto* encoded = encoded_t.flat<Variant>()(0).get<CompositeTensorVariant>();
 
     // Check that the encoded TypeSpec is compatible with the expected TypeSpec.

tensorflow/python/kernel_tests/composite_tensor_ops_test.py

@@ -18,11 +18,13 @@
 
 from tensorflow.python.eager import backprop
 from tensorflow.python.eager import context
+from tensorflow.python.framework import constant_op
 from tensorflow.python.framework import dtypes
 from tensorflow.python.framework import errors
 from tensorflow.python.framework import sparse_tensor
 from tensorflow.python.framework import test_util
 from tensorflow.python.ops import composite_tensor_ops
+from tensorflow.python.ops import gen_composite_tensor_ops
 from tensorflow.python.ops import gradients_impl
 from tensorflow.python.ops import math_ops
 from tensorflow.python.ops import parsing_ops
@@ -83,6 +85,18 @@ def testEncodingErrors(self, value, spec, message):
     with self.assertRaisesRegex(ValueError, message):
       composite_tensor_ops.composite_tensor_to_variants(value(), spec)
 
+  def testDecodingEmptyNonScalarTensorError(self):
+    if not context.executing_eagerly():
+      # Creating a variant tensor of an empty list is not allowed in eager mode.
+      return
+
+    with self.assertRaisesRegex(errors.InvalidArgumentError,
+                                'must not be an empty variant tensor'):
+      gen_composite_tensor_ops.CompositeTensorVariantToComponents(
+          encoded=constant_op.constant([], dtype=dtypes.variant),
+          metadata='',
+          Tcomponents=[dtypes.int32])
+
   def testRoundTripThroughTensorProto(self):
     value = ragged_factory_ops.constant([[1, 2], [3], [4, 5, 6]])
     encoded = composite_tensor_ops.composite_tensor_to_variants(value)