Fuzzer `php-fuzz-execute` crashes at `zend_lazy_object_init`
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Bug
Category: Engine
Status: Verified
- Dominant language
- C
- Stars
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- 8.1k
- Avg merge
- 2d 13h
- Merged PRs (30d)
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Description
Description
The following code:
<?php
class Test {
public function __isset($x) { $GLOBALS["obj"] = 24; return true; }
public function a($x) { }
}
$obj = new Test;
var_dump($obj->$name ?? 12);
?>
Resulted in this crashing call stack by the fuzzing driver php-fuzz-execute:
#6 __GI___assert_fail (assertion=0xdec74d "info", file=0xe24f2e "/src/php-src/Zend/zend_lazy_objects.c", line=110, function=0xe2576a "zend_lazy_object_info *zend_lazy_object_get_info(zend_object *)") at ./assert/assert.c:103
#7 zend_lazy_object_init () at Zend/zend_lazy_objects.c:513
#8 zend_std_read_property () at Zend/zend_object_handlers.c:954
#9 ZEND_FETCH_OBJ_IS_SPEC_CV_CV_HANDLER () at Zend/zend_vm_execute.h:52811
#10 fuzzer_execute_ex () at sapi/fuzzer/fuzzer-execute-common.h:59
#11 zend_execute () at Zend/zend_vm_execute.h:64385
#12 fuzzer_do_request_from_buffer () at sapi/fuzzer/fuzzer-sapi.c:274
#13 LLVMFuzzerTestOneInput () at sapi/fuzzer/fuzzer-execute.c:27
PHP Version
dbabbe180b157eeaac5002276667f1f56f0b4def 2025-06-10 22:35:56+0200
Operating System
Linux
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start by reproducing the supplied script with the php-fuzz-execute driver. Read Zend/zend_lazy_objects.c around zend_lazy_object_init and trace the property access through Zend/zend_object_handlers.c, then review the fuzzer entry points in sapi/fuzzer/fuzzer-execute-common.h and sapi/fuzzer/fuzzer-sapi.c. Done means the reproducer no longer triggers the assertion, with regression coverage if an appropriate test location is identified.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- c, php
- Domain
- backend, testing-qa
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 35/100