Vulnerability: Use after free and segfault in shape inference functions ### Impact
When running shape functions, some functions (such as `MutableHashTableShape`) produce extra output information in the form of a `ShapeAndType` struct. The shapes embedded in this struct are owned by an inference context that is cleaned up almost immediately; if the upstream code attempts to access this shape information, it can trigger a segfault.

`ShapeRefiner` is mitigating this for normal output shapes by cloning them (and thus putting the newly created shape under ownership of an inference context that will not die), but we were not doing the same for shapes and types. This commit fixes that by doing similar logic on output shapes and types.

### Patches
We have patched the issue in GitHub commit [ee119d4a498979525046fba1c3dd3f13a039fbb1](https://github.com/tensorflow/tensorflow/commit/ee119d4a498979525046fba1c3dd3f13a039fbb1).                                                                                                          

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.

### 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.
Vulnerability ID: GHSA-3hxh-8cp2-g4hg
CWE: CWE-416
Severity score: 6.6
Project: https://github.com/tensorflow/tensorflow
Published: 2021-08-25
File: tensorflow/core/common_runtime/shape_refiner.cc
Commit message: Fix segmentation fault in shape inference logic.

When running shape functions, some functions (such as `MutableHashTableShape`)
produce extra output information in the form of a `ShapeAndType` struct.  The
shapes embedded in this struct are owned by an inference context that is
cleaned up almost immediately; if the upstream code attempts to access this
shape information, it can trigger a segfault.

`ShapeRefiner` is mitigating this for normal output shapes by cloning them
(and thus putting the newly created shape under ownership of an inference
context that will not die), but we were not doing the same for shapes and
types.  This commit fixes that by doing similar logic on output shapes and
types.

PiperOrigin-RevId: 384761124
Change-Id: I07c0c42d29dfbb55bfa13ec1f09ef825fb0a1a1d
Commit author: Daniel Ellis

Vulnerable version (before fix):
 Status ShapeRefiner::InferShapesForFunctionSubNode(     TF_RETURN_IF_ERROR(outer_context->MakeShapeFromShapeProto(proto, &handle));     outer_context->set_output(index, handle);      auto* resource = node_context->input_handle_shapes_and_types(0);     if (resource) {       outer_context->set_output_handle_shapes_and_types(index, *resource);     }   } 

Fixed version (after fix):
 Status ShapeRefiner::InferShapesForFunctionSubNode(     TF_RETURN_IF_ERROR(outer_context->MakeShapeFromShapeProto(proto, &handle));     outer_context->set_output(index, handle);      const std::vector<ShapeAndType>* resource =         node_context->input_handle_shapes_and_types(0);     if (resource) {       // `ShapesAndType`s contain `ShapeHandle`s.  These `ShapeHandle`s point       // to `Shape`s that are owned by a different inference context too.  We       // need to copy them to the outer context to prevent them from being       // destroyed before they are used.       std::vector<ShapeAndType> copied_shapes_and_types;       for (auto& shape_and_type : *resource) {         ShapeHandle handle;         TensorShapeProto proto;         node_context->ShapeHandleToProto(shape_and_type.shape, &proto);         TF_RETURN_IF_ERROR(             outer_context->MakeShapeFromShapeProto(proto, &handle));         copied_shapes_and_types.push_back(             ShapeAndType(handle, shape_and_type.dtype, shape_and_type.type));       }        outer_context->set_output_handle_shapes_and_types(           index, copied_shapes_and_types);     }   } 

Patch:
patch: @@ -120,9 +120,26 @@ Status ShapeRefiner::InferShapesForFunctionSubNode(
     TF_RETURN_IF_ERROR(outer_context->MakeShapeFromShapeProto(proto, &handle));
     outer_context->set_output(index, handle);
 
-    auto* resource = node_context->input_handle_shapes_and_types(0);
+    const std::vector<ShapeAndType>* resource =
+        node_context->input_handle_shapes_and_types(0);
     if (resource) {
-      outer_context->set_output_handle_shapes_and_types(index, *resource);
+      // `ShapesAndType`s contain `ShapeHandle`s.  These `ShapeHandle`s point
+      // to `Shape`s that are owned by a different inference context too.  We
+      // need to copy them to the outer context to prevent them from being
+      // destroyed before they are used.
+      std::vector<ShapeAndType> copied_shapes_and_types;
+      for (auto& shape_and_type : *resource) {
+        ShapeHandle handle;
+        TensorShapeProto proto;
+        node_context->ShapeHandleToProto(shape_and_type.shape, &proto);
+        TF_RETURN_IF_ERROR(
+            outer_context->MakeShapeFromShapeProto(proto, &handle));
+        copied_shapes_and_types.push_back(
+            ShapeAndType(handle, shape_and_type.dtype, shape_and_type.type));
+      }
+
+      outer_context->set_output_handle_shapes_and_types(
+          index, copied_shapes_and_types);
     }
   }
path: tensorflow/core/common_runtime/shape_refiner.cc