Bug #81272 [Ver]: Segfault in var[] after array_slice with JIT
Edit report at https://bugs.php.net/bug.php?id=81272&edit=1
ID: 81272
Updated by: nikic@php.net
Reported by: dktapps at pmmp dot io
Summary: Segfault in var[] after array_slice with JIT
Status: Verified
Type: Bug
Package: JIT
Operating System: Windows 10
PHP Version: 8.0.8
-Assigned To:
+Assigned To: dmitry
Block user comment: N
Private report: N
New Comment:
SEPARATE_ARRAY currently only does something if MAY_BE_RCN. However, we also need to separate
immutable arrays.
I'm not sure how this is intended to work. Should array_slice func info specify MAY_BE_RCN, or
should SEPARATE_ARRAY be adjusted to always take possible immutable array into account?
Previous Comments:
------------------------------------------------------------------------
[2021-07-20 11:21:14] nikic@php.net
Reduced:
function test() {
$newPages = array_slice([], 0, 0);
$newPages[] = null;
}
test();
Presumably the case where array_slice() returns an interned empty array is not handled.
------------------------------------------------------------------------
[2021-07-18 19:25:54] dktapps at pmmp dot io
Description:
------------
When running the below script in PHP 8.0, a segfault occurs if opcache JIT is enabled
(opcache.jit=1205).
The following settings were used to reproduce the problem:
opcache.enable_cli=1
opcache.jit=1205
opcache.jit_buffer_size=128M
Test script:
---------------
<?php
class WritableBookPage{
public function __construct(string $text){}
}
class WritableBookBase{
/**
* @var WritableBookPage[]
* @phpstan-var list<WritableBookPage>
*/
private $pages = [];
/**
* Inserts a new page with the given text and moves other pages upwards.
*
* @return $this
*/
public function insertPage(int $pageId, string $pageText = "") : self{
if($pageId < 0 || $pageId > count($this->pages)){
throw new \InvalidArgumentException("Page ID must not be negative");
}
$newPages = array_slice($this->pages, 0, $pageId);
$newPages[] = new WritableBookPage($pageText);
array_push($newPages, ...array_slice($this->pages, $pageId));
$this->pages = $newPages;
return $this;
}
}
$book = new WritableBookBase;
$book->insertPage(0, "test");
Expected result:
----------------
The script should return with no output with exit code 0.
Actual result:
--------------
A segmentation fault occurs.
In VS, the following stacktrace appears:
> [Inline Frame] php8ts.dll!zend_hash_real_init_packed_ex(_zend_array *) Line 159 C
[Inline Frame] php8ts.dll!_zend_hash_index_add_or_update_i(_zend_array *) Line 1037 C
php8ts.dll!zend_hash_next_index_insert(_zend_array * ht, _zval_struct * pData) Line 1104 C
[External Code]
php8ts.dll!zend_file_handle_dtor(_zend_file_handle * fh) Line 226 C
[External Code]
php8ts.dll!zend_execute(_zend_op_array * op_array, _zval_struct * return_value) Line 58877 C
php8ts.dll!zend_execute_scripts(int type, _zval_struct * retval, int file_count, ...) Line 1681 C
php8ts.dll!php_execute_script(_zend_file_handle * primary_file) Line 2516 C
php.exe!do_cli(int argc, char * * argv) Line 951 C
php.exe!main(int argc, char * * argv) Line 1336 C
[External Code]
Additionally, in a Linux debug run (see https://github.com/dktapps/php-8-jit-bugs/runs/3098555756?check_suite_focus=true),
the following assertion failure appears:
php: /tmp/php-build/source/8.0.7/Zend/zend_hash.c:987: _zend_hash_index_add_or_update_i: Assertion
`(zend_gc_refcount(&(ht)->gc) == 1) || ((ht)->u.flags & (1<<6))' failed.
Aborted (core dumped)
------------------------------------------------------------------------
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Edit this bug report at https://bugs.php.net/bug.php?id=81272&edit=1
Thread (4 messages)