Revert temporary fuzz fix (#1000)

Signed-off-by: Ludvig Liljenberg <4257730+ludfjig@users.noreply.github.com>

Author: ludfjig

Cargo.lock

@@ -11,6 +11,7 @@ cargo-fuzz = true
 libfuzzer-sys = "0.4"
 hyperlight-testing = { workspace = true }
 hyperlight-host = { workspace = true, default-features = true, features = ["fuzzing"]}
+hyperlight-common = {workspace = true}
 
 [[bin]]
 name = "fuzz_host_print"

fuzz/Cargo.toml

@@ -18,17 +18,14 @@ limitations under the License.
 
 use std::sync::{Mutex, OnceLock};
 
+use hyperlight_common::flatbuffer_wrappers::guest_error::ErrorCode;
 use hyperlight_host::func::{ParameterValue, ReturnType};
 use hyperlight_host::sandbox::SandboxConfiguration;
-use hyperlight_host::sandbox::snapshot::Snapshot;
 use hyperlight_host::sandbox::uninitialized::GuestBinary;
 use hyperlight_host::{HyperlightError, MultiUseSandbox, UninitializedSandbox};
 use hyperlight_testing::simple_guest_for_fuzzing_as_string;
 use libfuzzer_sys::fuzz_target;
 
-// TODO: this SNAPSHOT is needed because of the memory leak in: https://github.com/hyperlight-dev/hyperlight/issues/826
-// This should be removed once the leak is fixed
-static SNAPSHOT: OnceLock<Mutex<Snapshot>> = OnceLock::new();
 static SANDBOX: OnceLock<Mutex<MultiUseSandbox>> = OnceLock::new();
 
 // This fuzz target tests all combinations of ReturnType and Parameters for `call_guest_function_by_name`.
@@ -44,27 +41,25 @@ fuzz_target!(
         )
         .unwrap();
 
-        let mut mu_sbox: MultiUseSandbox = u_sbox.evolve().unwrap();
-        let snapshot = mu_sbox.snapshot().unwrap();
+        let mu_sbox: MultiUseSandbox = u_sbox.evolve().unwrap();
         SANDBOX.set(Mutex::new(mu_sbox)).unwrap();
-        SNAPSHOT.set(Mutex::new(snapshot)).map_err(|_| "Snapshot already set").unwrap();
     },
 
     |data: (String, ReturnType, Vec<ParameterValue>)| {
         let (host_func_name, host_func_return, mut host_func_params) = data;
         let mut sandbox = SANDBOX.get().unwrap().lock().unwrap();
-        let snapshot = SNAPSHOT.get().unwrap().lock().unwrap();
-        sandbox.restore(&snapshot).unwrap();
-
-        host_func_params.insert(0, ParameterValue::String(host_func_name));
+        host_func_params.insert(0, ParameterValue::String(host_func_name.clone()));
         if let Err(e) = sandbox.call_type_erased_guest_function_by_name("FuzzHostFunc", host_func_return, host_func_params) {
             match e {
                 // the following are expected errors and occur frequently since
                 // we are randomly generating the function name and parameters
                 // to call with.
                 HyperlightError::HostFunctionNotFound(_) => {}
+                HyperlightError::GuestError(ErrorCode::HostFunctionError, msg) if msg == format!("HostFunction {} was not found", host_func_name) => {}
                 HyperlightError::UnexpectedNoOfArguments(_, _) => {},
+                HyperlightError::GuestError(ErrorCode::HostFunctionError, msg) if msg.contains("The number of arguments to the function is wrong") => {}
                 HyperlightError::ParameterValueConversionFailure(_, _) => {},
+                HyperlightError::GuestError(ErrorCode::HostFunctionError, msg) if msg.contains("Failed To Convert Parameter Value") => {}
 
                 // any other error should be reported
                 _ => panic!("Guest Aborted with Unexpected Error: {:?}", e),

fuzz/fuzz_targets/host_call.rs

@@ -88,6 +88,21 @@ impl GuestHandle {
         }
     }
 
+    pub fn get_host_return_raw(&self) -> Result<ReturnValue> {
+        let inner = self
+            .try_pop_shared_input_data_into::<FunctionCallResult>()
+            .expect("Unable to deserialize a return value from host")
+            .into_inner();
+
+        match inner {
+            Ok(ret) => Ok(ret),
+            Err(e) => Err(HyperlightGuestError {
+                kind: e.code,
+                message: e.message,
+            }),
+        }
+    }
+
     /// Call a host function without reading its return value from shared mem.
     /// This is used by both the Rust and C APIs to reduce code duplication.
     ///

src/hyperlight_guest/src/guest_handle/host_comm.rs

@@ -54,6 +54,11 @@ pub fn call_host_function_without_returning_result(
     handle.call_host_function_without_returning_result(function_name, parameters, return_type)
 }
 
+pub fn get_host_return_value_raw() -> Result<ReturnValue> {
+    let handle = unsafe { GUEST_HANDLE };
+    handle.get_host_return_raw()
+}
+
 pub fn get_host_return_value<T: TryFrom<ReturnValue>>() -> Result<T> {
     let handle = unsafe { GUEST_HANDLE };
     handle.get_host_return_value::<T>()

src/hyperlight_guest_bin/src/host_comm.rs

@@ -36,7 +36,7 @@ use core::ptr::write_volatile;
 
 use hyperlight_common::flatbuffer_wrappers::function_call::{FunctionCall, FunctionCallType};
 use hyperlight_common::flatbuffer_wrappers::function_types::{
-    ParameterType, ParameterValue, ReturnType,
+    ParameterType, ParameterValue, ReturnType, ReturnValue,
 };
 use hyperlight_common::flatbuffer_wrappers::guest_error::ErrorCode;
 use hyperlight_common::flatbuffer_wrappers::guest_log_level::LogLevel;
@@ -47,8 +47,8 @@ use hyperlight_guest::exit::{abort_with_code, abort_with_code_and_message};
 use hyperlight_guest_bin::guest_function::definition::GuestFunctionDefinition;
 use hyperlight_guest_bin::guest_function::register::register_function;
 use hyperlight_guest_bin::host_comm::{
-    call_host_function, call_host_function_without_returning_result, print_output_with_host_print,
-    read_n_bytes_from_user_memory,
+    call_host_function, call_host_function_without_returning_result, get_host_return_value_raw,
+    print_output_with_host_print, read_n_bytes_from_user_memory,
 };
 use hyperlight_guest_bin::memory::malloc;
 use hyperlight_guest_bin::{MIN_STACK_ADDRESS, guest_logger};
@@ -1665,7 +1665,23 @@ fn fuzz_host_function(func: FunctionCall) -> Result<Vec<u8>> {
         func.expected_return_type,
     )
     .expect("failed to call host function");
-    Ok(get_flatbuffer_result(()))
+
+    let host_return = get_host_return_value_raw();
+    match host_return {
+        Ok(return_value) => match return_value {
+            ReturnValue::Int(i) => Ok(get_flatbuffer_result(i)),
+            ReturnValue::UInt(i) => Ok(get_flatbuffer_result(i)),
+            ReturnValue::Long(i) => Ok(get_flatbuffer_result(i)),
+            ReturnValue::ULong(i) => Ok(get_flatbuffer_result(i)),
+            ReturnValue::Float(i) => Ok(get_flatbuffer_result(i)),
+            ReturnValue::Double(i) => Ok(get_flatbuffer_result(i)),
+            ReturnValue::String(str) => Ok(get_flatbuffer_result(str.as_str())),
+            ReturnValue::Bool(bool) => Ok(get_flatbuffer_result(bool)),
+            ReturnValue::Void(()) => Ok(get_flatbuffer_result(())),
+            ReturnValue::VecBytes(byte) => Ok(get_flatbuffer_result(byte.as_slice())),
+        },
+        Err(e) => Err(e),
+    }
 }
 
 #[no_mangle]