stream: fix TransformStream race on cancel with pending write

Signed-off-by: marcopiraccini <marco.piraccini@gmail.com>
PR-URL: #62040Fixes: #62036
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Paolo Insogna <paolo@cowtech.it>
Reviewed-By: Mattias Buelens <mattias@buelens.com>

Author: marcopiraccini

lib/internal/webstreams/transformstream.js

@@ -72,7 +72,6 @@ const {
 constassert=require('internal/assert');
 
 constkSkipThrow=Symbol('kSkipThrow');
-
 constgetNonWritablePropertyDescriptor=(value)=>{
 return{
 __proto__: null,
@@ -524,7 +523,12 @@ function transformStreamDefaultControllerError(controller, error) {
 
 asyncfunctiontransformStreamDefaultControllerPerformTransform(controller,chunk){
 try{
-returnawaitcontroller[kState].transformAlgorithm(chunk,controller);
+consttransformAlgorithm=controller[kState].transformAlgorithm;
+if(transformAlgorithm===undefined){
+// Algorithms were cleared by a concurrent cancel/abort/close.
+return;
+}
+returnawaittransformAlgorithm(chunk,controller);
 }catch(error){
 transformStreamError(controller[kState].stream,error);
 throwerror;

test/parallel/test-whatwg-transformstream-cancel-write-race.js

@@ -0,0 +1,51 @@
+'use strict';
+
+require('../common');
+const{ test }=require('node:test');
+constassert=require('node:assert');
+const{ TransformStream }=require('stream/web');
+const{ setTimeout }=require('timers/promises');
+
+// https://github.com/nodejs/node/issues/62036
+
+test('Late write racing with reader.cancel() should not throw an internal TypeError',async()=>{
+conststream=newTransformStream({
+transform(chunk,controller){
+controller.enqueue(chunk);
+},
+});
+
+awaitsetTimeout(0);
+
+constreader=stream.readable.getReader();
+constwriter=stream.writable.getWriter();
+
+// Release backpressure.
+constpendingRead=reader.read();
+
+// Simulate client disconnect / shutdown.
+constpendingCancel=reader.cancel(newError('client disconnected'));
+
+// Late write racing with cancel.
+constpendingLateWrite=writer.write('late-write');
+
+const[
+readResult,
+cancelResult,
+lateWriteResult,
+]=awaitPromise.allSettled([
+pendingRead,
+pendingCancel,
+pendingLateWrite,
+]);
+
+assert.strictEqual(readResult.status,'fulfilled');
+assert.strictEqual(cancelResult.status,'fulfilled');
+if(lateWriteResult.status==='rejected'){
+consterr=lateWriteResult.reason;
+constisNotAFunction=errinstanceofTypeError&&
+/transformAlgorithmisnotafunction/.test(err.message);
+assert.ok(!isNotAFunction,
+`Internal implementation error leaked: ${err.message}`);
+}
+});