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, 21 insertions, 0 deletions

diff --git a/spec/lib/gitlab/ci/config_spec.rb b/spec/lib/gitlab/ci/config_spec.rb
index 7f336ee853e..4e8bff3d738 100644
--- a/spec/lib/gitlab/ci/config_spec.rb
+++ b/spec/lib/gitlab/ci/config_spec.rb
@@ -90,6 +90,27 @@ describe Gitlab::Ci::Config do
       end
     end
 
+    context 'when yml is too big' do
+      let(:yml) do
+        <<~YAML
+          --- &1
+          - hi
+          - *1
+        YAML
+      end
+
+      describe '.new' do
+        it 'raises error' do
+          expect(Gitlab::Sentry).to receive(:track_exception)
+
+          expect { config }.to raise_error(
+            described_class::ConfigError,
+            /The parsed YAML is too big/
+          )
+        end
+      end
+    end
+
     context 'when config logic is incorrect' do
       let(:yml) { 'before_script: "ls"' }