Rescue SystemStackErrors during validation

Author: rmosolgo

lib/graphql/query/validation_pipeline.rb

@@ -90,6 +90,9 @@ def ensure_has_validated
         end
 
         @valid = @validation_errors.empty?
+      rescue SystemStackError => err
+        @valid = false
+        @schema.query_stack_error(@query, err)
       end
 
       # If there are max_* values, add them,

lib/graphql/schema.rb

@@ -1663,6 +1663,10 @@ def add_subscription_extension_if_necessary
         end
       end
 
+      def query_stack_error(query, err)
+        query.analysis_errors.push(GraphQL::AnalysisError.new("This query is too large to execute."))
+      end
+
       private
 
       def lazy_methods

spec/graphql/analysis/ast/max_query_depth_spec.rb

@@ -131,4 +131,20 @@
       assert_equal "Query has depth of 7, which exceeds max depth of 4", result.message
     end
   end
+
+  describe "when the query would cause a stack error" do
+    let(:query_string) {
+      str = "query { cheese(id: 1) { ".dup
+      n = 10_000
+      n.times { str << "similarCheese(source: SHEEP) { " }
+      str << "id "
+      n.times { str << "} " }
+      str << "} }"
+      str
+    }
+
+    it "returns an error" do
+      assert_equal ["This query is too large to execute."], query.static_errors.map(&:message)
+    end
+  end
 end