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fix(napi): Read reference ownership before calling finalizer to avoid crash #24203

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Jun 13, 2024
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Add regression test
  • Loading branch information
nathanwhit committed Jun 13, 2024
commit a69623b39d15b51c7d61da444a3886914feea08b
8 changes: 8 additions & 0 deletions tests/napi/object_wrap_test.js
Original file line number Diff line number Diff line change
Expand Up @@ -40,3 +40,11 @@ Deno.test("napi external arraybuffer", function () {
assertEquals(new Uint8Array(buf), new Uint8Array([1, 2, 3]));
buf = null;
});

Deno.test("napi object wrap userland owned", function () {
let obj = new objectWrap.NapiObjectOwned(1);
assertEquals(obj.get_value(), 1);
obj = null;
// force finalize callback to get called
globalThis.gc();
});
79 changes: 74 additions & 5 deletions tests/napi/src/object_wrap.rs
Original file line number Diff line number Diff line change
Expand Up @@ -5,6 +5,8 @@ use crate::napi_get_callback_info;
use crate::napi_new_property;
use napi_sys::ValueType::napi_number;
use napi_sys::*;
use std::cell::RefCell;
use std::collections::HashMap;
use std::os::raw::c_char;
use std::os::raw::c_void;
use std::ptr;
Expand All @@ -13,9 +15,36 @@ pub struct NapiObject {
counter: i32,
}

thread_local! {
// map from native object ptr to napi reference (this is similar to what napi-rs does)
static REFS: RefCell<HashMap<*mut c_void, napi_ref>> = RefCell::new(HashMap::new());
}

pub extern "C" fn finalize_napi_object(
env: napi_env,
finalize_data: *mut c_void,
_finalize_hint: *mut c_void,
) {
let obj = unsafe { Box::from_raw(finalize_data as *mut NapiObject) };
drop(obj);
if let Some(reference) =
REFS.with_borrow_mut(|map| map.remove(&finalize_data))
{
unsafe { napi_delete_reference(env, reference) };
}
}

impl NapiObject {
#[allow(clippy::new_ret_no_self)]
pub extern "C" fn new(env: napi_env, info: napi_callback_info) -> napi_value {
fn new_inner(
env: napi_env,
info: napi_callback_info,
finalizer: napi_finalize,
out_ptr: Option<*mut napi_ref>,
) -> napi_value {
assert!(matches!(
(finalizer, out_ptr),
(None, None) | (Some(_), Some(_))
));
let mut new_target: napi_value = ptr::null_mut();
assert_napi_ok!(napi_get_new_target(env, info, &mut new_target));
let is_constructor = !new_target.is_null();
Expand All @@ -33,21 +62,42 @@ impl NapiObject {
assert_napi_ok!(napi_get_value_int32(env, args[0], &mut value));

let obj = Box::new(Self { counter: value });
let obj_raw = Box::into_raw(obj) as *mut c_void;
assert_napi_ok!(napi_wrap(
env,
this,
Box::into_raw(obj) as *mut c_void,
None,
ptr::null_mut(),
obj_raw,
finalizer,
ptr::null_mut(),
out_ptr.unwrap_or(ptr::null_mut())
));

if let Some(p) = out_ptr {
if finalizer.is_some() {
REFS.with_borrow_mut(|map| map.insert(obj_raw, unsafe { p.read() }));
}
}

return this;
}

unreachable!();
}

#[allow(clippy::new_ret_no_self)]
pub extern "C" fn new(env: napi_env, info: napi_callback_info) -> napi_value {
Self::new_inner(env, info, None, None)
}

#[allow(clippy::new_ret_no_self)]
pub extern "C" fn new_with_finalizer(
env: napi_env,
info: napi_callback_info,
) -> napi_value {
let mut out = ptr::null_mut();
Self::new_inner(env, info, Some(finalize_napi_object), Some(&mut out))
}

pub extern "C" fn set_value(
env: napi_env,
info: napi_callback_info,
Expand Down Expand Up @@ -148,4 +198,23 @@ pub fn init(env: napi_env, exports: napi_value) {
"NapiObject\0".as_ptr() as *const c_char,
cons,
));

let mut cons: napi_value = ptr::null_mut();
assert_napi_ok!(napi_define_class(
env,
c"NapiObjectOwned".as_ptr(),
usize::MAX,
Some(NapiObject::new_with_finalizer),
ptr::null_mut(),
properties.len(),
properties.as_ptr(),
&mut cons,
));

assert_napi_ok!(napi_set_named_property(
env,
exports,
"NapiObjectOwned\0".as_ptr() as *const c_char,
cons,
));
}
1 change: 1 addition & 0 deletions tests/napi/tests/napi_tests.rs
Original file line number Diff line number Diff line change
Expand Up @@ -69,6 +69,7 @@ fn napi_tests() {
.arg("--allow-env")
.arg("--allow-ffi")
.arg("--allow-run")
.arg("--v8-flags=--expose-gc,--gc-stats=1")
.arg("--config")
.arg(deno_config_path())
.arg("--no-lock")
Expand Down