Prevent Billion Laughs attack

It keeps track of the memory being used when loading the YAML file
as well as the depth of nesting.
Track exception when YAML is too big

1 files changed, 43 insertions, 0 deletions

diff --git a/spec/lib/gitlab/utils/deep_size_spec.rb b/spec/lib/gitlab/utils/deep_size_spec.rb
new file mode 100644
index 00000000000..1e619a15980
--- /dev/null
+++ b/spec/lib/gitlab/utils/deep_size_spec.rb
@@ -0,0 +1,43 @@
+require 'spec_helper'
+
+describe Gitlab::Utils::DeepSize do
+  let(:data) do
+    {
+      a: [1, 2, 3],
+      b: {
+        c: [4, 5],
+        d: [
+          { e: [[6], [7]] }
+        ]
+      }
+    }
+  end
+
+  let(:max_size) { 1.kilobyte }
+  let(:max_depth) { 10 }
+  let(:deep_size) { described_class.new(data, max_size: max_size, max_depth: max_depth) }
+
+  describe '#evaluate' do
+    context 'when data within size and depth limits' do
+      it 'returns true' do
+        expect(deep_size).to be_valid
+      end
+    end
+
+    context 'when data not within size limit' do
+      let(:max_size) { 200.bytes }
+
+      it 'returns false' do
+        expect(deep_size).not_to be_valid
+      end
+    end
+
+    context 'when data not within depth limit' do
+      let(:max_depth) { 2 }
+
+      it 'returns false' do
+        expect(deep_size).not_to be_valid
+      end
+    end
+  end
+end