child_process: treat ipc length header as unsigned uint32

Fixes: #61312
PR-URL: #61344
Reviewed-By: Aviv Keller <me@aviv.sh>

Author: islandryu

lib/internal/child_process/serialization.js

@@ -74,12 +74,12 @@ const advanced = {
 while(messageBufferHead.length>=4){
 // We call `readUInt32BE` manually here, because this is faster than first converting
 // it to a buffer and using `readUInt32BE` on that.
-constfullMessageSize=(
+constfullMessageSize=((
 messageBufferHead[0]<<24|
 messageBufferHead[1]<<16|
 messageBufferHead[2]<<8|
 messageBufferHead[3]
-)+4;
+)>>>0)+4;
 
 if(channel[kMessageBufferSize]<fullMessageSize)break;
 

test/parallel/test-child-process-fork-advanced-header-serialization.js

@@ -0,0 +1,42 @@
+'use strict';
+constcommon=require('../common');
+constassert=require('assert');
+const{ fork }=require('child_process');
+constfs=require('fs');
+
+if(process.argv[2]==='child-buffer'){
+constv=process.argv[3];
+constpayload=Buffer.from([
+(v>>24)&0xFF,
+(v>>16)&0xFF,
+(v>>8)&0xFF,
+v&0xFF,
+]);
+constfd=process.channel?.fd;
+if(fd===undefined){
+// skip test
+process.exit(0);
+}
+fs.writeSync(fd,payload);
+return;
+}
+
+consttestCases=[
+0x00000001,
+0x7fffffff,
+0x80000000,
+0x80000001,
+0xffffffff,
+];
+
+for(constsizeoftestCases){
+constchild=fork(__filename,['child-buffer',size],{
+serialization: 'advanced',
+stdio: ['inherit','inherit','inherit','ipc'],
+});
+
+child.on('exit',common.mustCall((code,signal)=>{
+assert.strictEqual(code,0);
+assert.strictEqual(signal,null);
+}));
+}