Rescue DN normalization attempts

lib/gitlab/ldap/person.rb

@@ -43,6 +43,11 @@ module Gitlab
         else
           normalize_uid(uid_or_dn)
         end
+      rescue StandardError => e
+        Rails.logger.info("Returning original DN \"#{uid_or_dn}\" due to error during normalization attempt: #{e.message}")
+        Rails.logger.info(e.backtrace.join("\n"))
+
+        uid_or_dn
       end
 
       # Returns true if the string looks like a DN rather than a UID.
@@ -59,6 +64,11 @@ module Gitlab
       # 2. The string is downcased (for case-insensitivity)
       def self.normalize_uid(uid)
         normalize_dn_part(uid)
+      rescue StandardError => e
+        Rails.logger.info("Returning original UID \"#{uid}\" due to error during normalization attempt: #{e.message}")
+        Rails.logger.info(e.backtrace.join("\n"))
+
+        uid
       end
 
       # Returns the DN in a normalized form.
@@ -69,6 +79,11 @@ module Gitlab
         dn.split(/(?<!\\)([,+=])/).map do |part|
           normalize_dn_part(part)
         end.join('')
+      rescue StandardError => e
+        Rails.logger.info("Returning original DN \"#{dn}\" due to error during normalization attempt: #{e.message}")
+        Rails.logger.info(e.backtrace.join("\n"))
+
+        dn
       end
 
       def initialize(entry, provider)

spec/lib/gitlab/ldap/person_spec.rb

@@ -82,18 +82,42 @@ describe Gitlab::LDAP::Person do
 
     it_behaves_like 'normalizes the DN'
     it_behaves_like 'normalizes the UID'
+
+    context 'with an exception during normalization' do
+      let(:given) { described_class } # just something that will cause an exception
+
+      it 'returns the given object unmodified' do
+        expect(subject).to eq(given)
+      end
+    end
   end
 
   describe '.normalize_uid' do
     subject { described_class.normalize_uid(given) }
 
     it_behaves_like 'normalizes the UID'
+
+    context 'with an exception during normalization' do
+      let(:given) { described_class } # just something that will cause an exception
+
+      it 'returns the given UID unmodified' do
+        expect(subject).to eq(given)
+      end
+    end
   end
 
   describe '.normalize_dn' do
     subject { described_class.normalize_dn(given) }
 
     it_behaves_like 'normalizes the DN'
+
+    context 'with an exception during normalization' do
+      let(:given) { described_class } # just something that will cause an exception
+
+      it 'returns the given DN unmodified' do
+        expect(subject).to eq(given)
+      end
+    end
   end
 
   describe '.dn?' do