Process.title gets corrupted in case process.argv[2] is too long

[Mitko-Kerezov]

• Version: v10.15.1
• Platform: Ubuntu 18.04

Please see the script below:

const printTitle = () => {
    console.log(`Process version ${process.version}`);
    console.log(`Process title ${process.title}`);
};

printTitle();
printTitle();

I am executing this script in the terminal with node script-name.js

The output is as follows:

• With no additional command line arguments:

Process version v10.15.1
Process title node
Process version v10.15.1
Process title node

• With a command line argument of length 700

Process version v10.15.1
Process title
Process version v10.15.1
Process title �PP��

It appears that process.title (and only process.title as far as I can tell) gets corrupted in case provess,argv[2] is of substantial length. Note that each time the second print of process.title yields a different result.

I have read the docs regarding process.title and as far as I can tell there is only an issue with assigning a large string to process.title.

[bnoordhuis]

I can't reproduce exactly what you're describing but I can reproduce something:

$ ./out/Release/node -p process.title `base64 /dev/urandom | head -c 475`
./out/Release/node

$ ./out/Release/node -p process.title `base64 /dev/urandom | head -c 476`
# nothing

Note that the length of the four arguments are 512 and 513 respectively when you account for trailing nul bytes. Coincidence? I don't think so!

[bnoordhuis]

Okay, found it:

node/src/node_process_object.cc

Lines 35 to 36 in 60de60a

	char buffer[512];
	uv_get_process_title(buffer, sizeof(buffer));

Node.js passes a fixed-size buffer to libuv and neglects to check the return value. Fix on the way.

[Mitko-Kerezov]

@bnoordhuis
I initially stumbled upon the issue with an argument which was 700 bytes long. Bear in mind that you have to print the title at least twice in order to end up with some "corrupted" memory inside.
Having said that, interestingly the following code does not reproduce the issue:

node --eval 'console.log(process.title); console.log(process.title)' `base64 /dev/urandom | head -c 700`

and neither does the following:

node --eval 'function test() {console.log(process.title); console.log(process.title)} test()' `base64 /dev/urandom | head -c 700`

it is only with a file that I manage to reproduce it and only if the file contains a function execution.

Meaning if I have:
test.js:

console.log(process.title);
console.log(process.title);

And then execute

node test.js `base64 /dev/urandom | head -c 700`

I do not reproduce the issue.

---

Only with
test.js

const printTitle = () => {
    console.log(`Process title ${process.title}`);
};

printTitle();
printTitle();

and then executing:

node test.js `base64 /dev/urandom | head -c 700`

Only then do I get some memory chunks inside process.title