Add fuzz targets for module instantiation.

fuzz/fuzz_targets/instantiate.rs

@@ -0,0 +1,27 @@
+#![no_main]
+
+#[macro_use]
+extern crate libfuzzer_sys;
+extern crate cranelift_codegen;
+extern crate cranelift_native;
+extern crate wasmparser;
+extern crate wasmtime_environ;
+extern crate wasmtime_jit;
+
+use cranelift_codegen::settings;
+use wasmparser::validate;
+use wasmtime_jit::{instantiate, Compiler, NullResolver};
+
+fuzz_target!(|data: &[u8]| {
+    if !validate(data, None) {
+        return;
+    }
+    let flag_builder = settings::builder();
+    let isa_builder = cranelift_native::builder().unwrap_or_else(|_| {
+        panic!("host machine is not a supported target");
+    });
+    let isa = isa_builder.finish(settings::Flags::new(flag_builder));
+    let mut compiler = Compiler::new(isa);
+    let mut imports_resolver = NullResolver {};
+    let _instance = instantiate(&mut compiler, data, &mut imports_resolver).unwrap();
+});