fix: instrumention of nested records, and records with annotated fields

Using ClassWriter without ClassReader in asm, seems to produce
corrupted bytecode for nested records and records with annotated fields.

Prior to this fix, a segfault was triggered for nested records that
use Jazzer annotations when Jazzer was trying to access data on record
components, when trying to create a record mutator.

In addition, for non-nested records with annotated fields as for example:
record Address(byte @WithLength(max=10) [] data) {}
no suitable mutator could be found.

Author: oetr

src/main/java/com/code_intelligence/jazzer/instrumentor/TraceDataFlowInstrumentor.kt

@@ -52,7 +52,7 @@ internal class TraceDataFlowInstrumentor(
             }
         }
 
-        val writer = ClassWriter(ClassWriter.COMPUTE_MAXS)
+        val writer = ClassWriter(reader, ClassWriter.COMPUTE_MAXS)
         node.accept(writer)
         return writer.toByteArray()
     }

tests/BUILD.bazel

@@ -1077,6 +1077,35 @@ java_fuzz_target_test(
     ],
 )
 
+java_fuzz_target_test(
+    name = "NestedRecordFuzzer",
+    timeout = "short",
+    srcs = [
+        "src/test/java/com/example/NestedRecordFuzzer.java",
+    ],
+    fuzzer_args = [
+        "-print_final_stats=1",
+        "-runs=10000",
+    ],
+    javacopts = [
+        "--release",
+        "17",
+    ],
+    tags = [
+        "no-jdk8",
+    ],
+    target_class = "com.example.NestedRecordFuzzer",
+    runtime_deps = [
+        "@maven//:org_junit_jupiter_junit_jupiter_engine",
+    ],
+    deps = [
+        "//deploy:jazzer-junit",
+        "//deploy:jazzer-project",
+        "@maven//:org_junit_jupiter_junit_jupiter_api",
+        "@maven//:org_junit_jupiter_junit_jupiter_params",
+    ],
+)
+
 java_fuzz_target_test(
     name = "BigDecimalFuzzer",
     srcs = [

tests/src/test/java/com/example/NestedRecordFuzzer.java

@@ -0,0 +1,39 @@
+/*
+ * Copyright 2024 Code Intelligence GmbH
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example;
+
+import com.code_intelligence.jazzer.junit.FuzzTest;
+import com.code_intelligence.jazzer.mutation.annotation.NotNull;
+import com.code_intelligence.jazzer.mutation.annotation.WithLength;
+
+/**
+ * This regression test checks if we instrument fuzz test classes with nested records correctly, and
+ * can start a fuzzing run at all without getting segfaults.
+ */
+public class NestedRecordFuzzer {
+  record Address(@NotNull String street, byte @NotNull @WithLength(min = 3, max = 4) [] data) {}
+
+  @FuzzTest
+  public void test(Address address) {
+    if (address != null) {
+      byte[] data = address.data();
+      if (data.length < 3 || data.length > 4) {
+        throw new IllegalStateException("Data length out of bounds: " + data.length);
+      }
+    }
+  }
+}