Add malformed test cases (#3459)

tests/malformed/README.md

@@ -0,0 +1,18 @@
+# Malformed Test Cases
+This folder contains malformed test cases collected from github and peach fuzzer. More cases should be added to here when found.
+
+# Note
+Malformed tests are currently for testing running mode of interpreter including classic interpreter and fast interpreter.
+
+# Test
+Use the provided python script to test a wasm runtime:
+``` shell
+python malformed_test.py -r "path/to/runtime"
+```
+
+For example you can test wasmtime with:
+``` shell
+python malformed_test.py -r "/usr/bin/wasmtime"
+```
+If no args is passed to the script, the default runtime `/usr/bin/iwasm` will be used.
+