protocolbuffers/protobuf

PHP Extension - Segmentation fault when serialize() is called on a protobuf message

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#24369 opened on Nov 8, 2025

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help wanted

Description

The PHP C extension segfaults when serialize() is called on a protobuf message.

[!IMPORTANT]
This is a unusual use case but the extension should not crash if a proto message is serialize by mistake.

What version of protobuf and what language are you using? Version: main Language: php OS: Linux

What did you do?

<?php
# serialize_segfault.php

require_once (dirname(__DIR__) . '/vendor/autoload.php');

use Foo\TestMessage;

$msg = new TestMessage(['optional_string' => "Hello, World!"]);

serialize($msg);

# Compile the extension 
./php/tests/compile_extension.sh

# Run script
php -d display_errors=on -dextension=../ext/google/protobuf/modules/protobuf.so  serialize_segfault.php

What did you expect to see

# no errors.

What did you see instead?

Segmentation fault

Patch here

Contributor guide

Tech stack
phpc
Domain
backend
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
PHP developmentC programmingProtobuf basicsCompiling PHP extensions
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
40
Research direction
Review the provided patch from ChessCom (commit fd853cd) that fixes the segfault. The issue is in the PHP C extension; the patch likely modifies how the internal representation handles serialize() calls. Replicate the crash by compiling the extension and running the PHP script, then apply the patch and verify the fix. Test edge cases and consider adding a regression test in the PHP tests directory.