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Verify wasm module exports malloc/free #153

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Verify wasm module exports malloc/free #153

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59 changes: 35 additions & 24 deletions src/wasm_runtime/src/module.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -120,6 +120,39 @@ fn init_wasm_runtime() -> Result<Vec<u8>> {
Ok(get_flatbuffer_result::<i32>(0))
}

// Helper function to handle common module loading logic after module creation
fn instantiate_module(module: Module, engine: &Engine) -> Result<()> {
let linker = CUR_LINKER.lock();
let linker = linker.deref().as_ref().ok_or(HyperlightGuestError::new(
ErrorCode::GuestError,
"impossible: wasm runtime has no valid linker".to_string(),
))?;

let mut store = Store::new(engine, ());
let instance = linker.instantiate(&mut store, &module)?;

// Module must export malloc and free as these
// are used to marshal param/return values
if instance.get_func(&mut store, "malloc").is_none() {
Comment on lines +134 to +136
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this is only true if the module uses complex data types like string? I think simple args like int and such can be directly used on the stack

This rust example doesn't export malloc and seems to be working https://github.com/hyperlight-dev/hyperlight-wasm/blob/main/src/rust_wasm_samples/src/lib.rs

return Err(HyperlightGuestError::new(
ErrorCode::GuestError,
"WASM module must export 'malloc' function".to_string(),
));
}

if instance.get_func(&mut store, "free").is_none() {
return Err(HyperlightGuestError::new(
ErrorCode::GuestError,
"WASM module must export 'free' function".to_string(),
));
}

*CUR_MODULE.lock() = Some(module);
*CUR_STORE.lock() = Some(store);
*CUR_INSTANCE.lock() = Some(instance);
Ok(())
}

fn load_wasm_module(function_call: &FunctionCall) -> Result<Vec<u8>> {
if let (
ParameterValue::VecBytes(ref wasm_bytes),
Expand All @@ -130,19 +163,8 @@ fn load_wasm_module(function_call: &FunctionCall) -> Result<Vec<u8>> {
&function_call.parameters.as_ref().unwrap()[1],
&*CUR_ENGINE.lock(),
) {
let linker = CUR_LINKER.lock();
let linker = linker.deref().as_ref().ok_or(HyperlightGuestError::new(
ErrorCode::GuestError,
"impossible: wasm runtime has no valid linker".to_string(),
))?;

let module = unsafe { Module::deserialize(engine, wasm_bytes)? };
let mut store = Store::new(engine, ());
let instance = linker.instantiate(&mut store, &module)?;

*CUR_MODULE.lock() = Some(module);
*CUR_STORE.lock() = Some(store);
*CUR_INSTANCE.lock() = Some(instance);
instantiate_module(module, engine)?;
Ok(get_flatbuffer_result::<i32>(0))
} else {
Err(HyperlightGuestError::new(
Expand All @@ -158,19 +180,8 @@ fn load_wasm_module_phys(function_call: &FunctionCall) -> Result<Vec<u8>> {
&function_call.parameters.as_ref().unwrap()[1],
&*CUR_ENGINE.lock(),
) {
let linker = CUR_LINKER.lock();
let linker = linker.deref().as_ref().ok_or(HyperlightGuestError::new(
ErrorCode::GuestError,
"impossible: wasm runtime has no valid linker".to_string(),
))?;

let module = unsafe { Module::deserialize_raw(engine, platform::map_buffer(*phys, *len))? };
let mut store = Store::new(engine, ());
let instance = linker.instantiate(&mut store, &module)?;

*CUR_MODULE.lock() = Some(module);
*CUR_STORE.lock() = Some(store);
*CUR_INSTANCE.lock() = Some(instance);
instantiate_module(module, engine)?;
Ok(get_flatbuffer_result::<()>(()))
} else {
Err(HyperlightGuestError::new(
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