Infinite loop in `encode.js`

[ajmeese7]

New Issue Checklist

• I am not disclosing a vulnerability.
• I am not just asking a question.
• I have searched through existing issues.
• I can reproduce the issue with the latest versions of Parse Server and the Parse JS SDK.

Issue Description

The encode function is called recursively without a ceiling, causing the entire service to crash with no hint as to the originating call, even with VERBOSE=1 enabled. All I know is that the error is thrown from this line:

if (value && typeof value === 'object') {
  const output = {};
  for (const k in value) {
+   output[k] = encode(value[k], disallowObjects, forcePointers, seen, offline);
  }
  return output;
}

Steps to reproduce

Unsure, inherited legacy code and there is no hint as to which network call is causing this issue.

Actual Outcome

Program errors out without any hint as to where the error is coming from.

Expected Outcome

The function to execute properly. Two possible improvements to the library come to mind:

1. Give further context about where the error is coming from
2. Have a limit on the number of calls within the function and truncate after the limit is hit, giving a warning in the console but not causing the program to error out

Environment

Server

• Parse Server version: 7.0.0
• Operating system: node:18 Docker image
• Local or remote host (AWS, Azure, Google Cloud, Heroku, Digital Ocean, etc): Local

Database

• System (MongoDB or Postgres): MongoDB
• Database version: 5.9.2
• Local or remote host (MongoDB Atlas, mLab, AWS, Azure, Google Cloud, etc): Local

Client

• Parse JS SDK version: 5.0.0

Logs

An uncaught exception occurred: Maximum call stack size exceededStack Trace:
RangeError: Maximum call stack size exceeded
    at encode (/api/node_modules/.pnpm/parse@5.0.0/node_modules/parse/lib/node/encode.js:23:16)
    at /api/node_modules/.pnpm/parse@5.0.0/node_modules/parse/lib/node/encode.js:61:14
    at Array.map (<anonymous>)
    at encode (/api/node_modules/.pnpm/parse@5.0.0/node_modules/parse/lib/node/encode.js:60:18)
    at encode (/api/node_modules/.pnpm/parse@5.0.0/node_modules/parse/lib/node/encode.js:67:19)
    at encode (/api/node_modules/.pnpm/parse@5.0.0/node_modules/parse/lib/node/encode.js:67:19)
    at encode (/api/node_modules/.pnpm/parse@5.0.0/node_modules/parse/lib/node/encode.js:67:19)
    at encode (/api/node_modules/.pnpm/parse@5.0.0/node_modules/parse/lib/node/encode.js:67:19)
    at encode (/api/node_modules/.pnpm/parse@5.0.0/node_modules/parse/lib/node/encode.js:67:19)

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[mtrezza]

Have a limit on the number of calls within the function and truncate after the limit is hit, giving a warning in the console but not causing the program to error out

Not sure about warning; this is such a general method that encodes a Parse Object; we wouldn't know what exactly the effect is if we just "truncate" the encoding of an object. I believe encoding should fail after n iterations, whatever we decide a reasonable n to be, causing the calling method to fail and produce an error. To determine a reasonable n we would need to better understand in which cases a recursive calling happens.

As to your specific case, if you add a limit with n say 1000 and then let the calling op fail and log a detailed error, then you would also know what was causing this. Such a limit should be easy to implement. If you open a PR, then we can release it as alpha version, you can test it out in production and see what's causing this.

[dplewis]

I have run into this issue as well returning objects from a certain API in Cloud Code functions. I deconstructed the object manually or find if the object has a toJSON() function and return it.

In cloud code you can basically return anything. If it happens to be to an object with circular references then you will run into this issue.

Parse.Cloud.define('Circular', () => {
  const a = {};
  const b = {};
  a.b = b;
  b.a = a;
  return a;
  // const object = new Parse.Object('Test');
  // object.set('a', a);
  // return object.save()
});

[ajmeese7]

Whenever I used the logging currently added in the PR, this is the output I got:

2024-04-03 10:51:12 Encoding object failed due to high number of recursive calls, likely caused by circular reference within object.
2024-04-03 10:51:12 Value causing potential infinite recursion: 4184
2024-04-03 10:51:12 Disallow objects: false
2024-04-03 10:51:12 Force pointers: false
2024-04-03 10:51:12 Seen: []
2024-04-03 10:51:12 Offline: undefined
2024-04-03 10:51:12 An uncaught exception occurred: Encoding object failed due to high number of recursive calls, likely caused by circular reference within object.Stack Trace:
2024-04-03 10:51:12 Error: Encoding object failed due to high number of recursive calls, likely caused by circular reference within object.
2024-04-03 10:51:12     at encode (/api/node_modules/.pnpm/parse@5.0.0/node_modules/parse/lib/node/encode.js:34:11)
2024-04-03 10:51:12     at encode (/api/node_modules/.pnpm/parse@5.0.0/node_modules/parse/lib/node/encode.js:79:19)
2024-04-03 10:51:12     at encode (/api/node_modules/.pnpm/parse@5.0.0/node_modules/parse/lib/node/encode.js:79:19)
2024-04-03 10:51:12     at encode (/api/node_modules/.pnpm/parse@5.0.0/node_modules/parse/lib/node/encode.js:79:19)
2024-04-03 10:51:12     at encode (/api/node_modules/.pnpm/parse@5.0.0/node_modules/parse/lib/node/encode.js:79:19)
2024-04-03 10:51:12     at encode (/api/node_modules/.pnpm/parse@5.0.0/node_modules/parse/lib/node/encode.js:79:19)
2024-04-03 10:51:12     at encode (/api/node_modules/.pnpm/parse@5.0.0/node_modules/parse/lib/node/encode.js:79:19)
2024-04-03 10:51:12     at encode (/api/node_modules/.pnpm/parse@5.0.0/node_modules/parse/lib/node/encode.js:79:19)
2024-04-03 10:51:12     at encode (/api/node_modules/.pnpm/parse@5.0.0/node_modules/parse/lib/node/encode.js:79:19)

Does this make sense to you at all? I'm not sure why some number would cause this issue, or if that's just the console doing a bad job of stringifying whatever the object in question is. In case it was the stringifying, I changed the print code to:

console.error('Value causing potential infinite recursion:', JSON.stringify(value, null, 4));

And the next run's output was Value causing potential infinite recursion: 266328, which again provides very little information and no valuable intel to act on.

[mtrezza]

I'd like to point to my comment. Maybe it makes sense to properly handle circular references, instead of causing a stack overflow.