fix: properly instrument nested records

When passing ClassReader to ClassWriter, ASM can copy constant pool
entries directly from the original bytecode. Attributes that reference
the constant pool remain valid.

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.

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 +1077,37 @@ java_fuzz_target_test(
     ],
 )
 
+java_fuzz_target_test(
+    name = "NestedRecordFuzzer",
+    timeout = "short",
+    srcs = [
+        "src/test/java/com/example/NestedRecordFuzzer.java",
+    ],
+    # 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.
+    fuzzer_args = [
+        "-print_final_stats=1",
+        "-runs=1",
+    ],
+    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 +1,27 @@
+/*
+ * 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;
+
+public class NestedRecordFuzzer {
+  record Address(@NotNull String street, String city, String zipCode) {}
+
+  @FuzzTest
+  public void test(Address ignored) {}
+}