[fuzz] fix json fuzzer (protobuf parsing error) (envoyproxy#15459)

Signed-off-by: Asra Ali <asraa@google.com>
yanavlasov · Mar 19, 2021 · 2b8a744 · 2b8a744
1 parent 9a89e31
commit 2b8a744
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Showing 2 changed files with 10 additions and 2 deletions.
diff --git a/test/common/json/json_corpus/protobuf_invalid_recursion b/test/common/json/json_corpus/protobuf_invalid_recursion
diff --git a/test/common/json/json_fuzz_test.cc b/test/common/json/json_fuzz_test.cc
@@ -25,8 +25,15 @@ DEFINE_FUZZER(const uint8_t* buf, size_t len) {
     MessageUtil::loadFromJson(json_string, message);
     // We should be able to serialize, parse again and get the same result.
     ProtobufWkt::Struct message2;
-    MessageUtil::loadFromJson(MessageUtil::getJsonStringFromMessageOrDie(message), message2);
-    FUZZ_ASSERT(TestUtility::protoEqual(message, message2));
+    // This can sometimes fail on too deep recursion in case protobuf parsing is configured to have
+    // less recursion depth than json parsing in the proto library.
+    // This is the only version of MessageUtil::getJsonStringFromMessage function safe to use on
+    // untrusted inputs.
+    std::string deserialized = MessageUtil::getJsonStringFromMessageOrError(message);
+    if (!absl::StartsWith(deserialized, "Failed to convert")) {
+      MessageUtil::loadFromJson(deserialized, message2);
+      FUZZ_ASSERT(TestUtility::protoEqual(message, message2));
+    }
 
     // MessageUtil::getYamlStringFromMessage automatically convert types, so we have to do another
     // round-trip.