Fix

Author: jandro996

dd-java-agent/appsec/src/main/java/com/datadog/appsec/event/data/ObjectIntrospection.java

@@ -345,6 +345,9 @@ private static boolean setAccessible(Field field) {
   }
 
   private static String checkStringLength(final String str, final State state) {
+    if (str == null) {
+      return null;
+    }
     if (str.length() > MAX_STRING_SIZE) {
       state.stringTooLong = true;
       return str.substring(0, MAX_STRING_SIZE);

dd-java-agent/appsec/src/test/groovy/com/datadog/appsec/event/data/ObjectIntrospectionSpecification.groovy

@@ -354,6 +354,14 @@ class ObjectIntrospectionSpecification extends DDSpecification {
     MAPPER.readTree('{"key": "value"}')            || [key: 'value']
   }
 
+  void 'jackson text nodes with null textual value are handled gracefully'() {
+    given:
+    def node = new com.fasterxml.jackson.databind.node.NullTextJsonNode()
+
+    expect:
+    convert(node, ctx) == null
+  }
+
   void 'jackson nested structures'() {
     when:
     final result = convert(input, ctx)

dd-java-agent/appsec/src/test/groovy/com/fasterxml/jackson/databind/node/NullTextJsonNode.groovy

@@ -0,0 +1,34 @@
+package com.fasterxml.jackson.databind.node
+
+import com.fasterxml.jackson.core.JsonGenerator
+import com.fasterxml.jackson.core.JsonToken
+import com.fasterxml.jackson.databind.JsonNode
+import com.fasterxml.jackson.databind.SerializerProvider
+import java.io.IOException
+
+class NullTextJsonNode extends BaseJsonNode {
+  @Override
+  JsonNodeType getNodeType() {
+    return JsonNodeType.STRING
+  }
+
+  @Override
+  String textValue() {
+    return null
+  }
+
+  @Override
+  JsonToken asToken() {
+    return JsonToken.VALUE_STRING
+  }
+
+  @Override
+  void serialize(JsonGenerator gen, SerializerProvider serializers) throws IOException {
+    gen.writeNull()
+  }
+
+  @Override
+  JsonNode deepCopy() {
+    return this
+  }
+}