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Fix GH-23088: Stack overflow when comparing deeply nested arrays #23090

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Fix GH-23088: Stack overflow when comparing deeply nested arrays #23090

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4 changes: 4 additions & 0 deletions NEWS
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Original file line number Diff line number Diff line change
Expand Up @@ -2,6 +2,10 @@ PHP NEWS
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?? ??? ????, PHP 8.4.25

- Core:
. Fixed bug GH-23088 (Stack overflow when comparing deeply nested arrays).
(Lazizbek Ergashev)

- Date:
. Fixed leak on double DatePeriod::__construct() call. (ilutov)

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40 changes: 40 additions & 0 deletions Zend/tests/gh23088.phpt
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@@ -0,0 +1,40 @@
--TEST--
GH-23088 (Stack overflow when comparing deeply nested arrays)
--SKIPIF--
<?php
if (ini_get('zend.max_allowed_stack_size') === false) {
die('skip No stack limit support');
}
if (getenv('SKIP_ASAN')) {
die('skip ASAN needs different stack limit setting due to more stack space usage');
}
?>
--INI--
zend.max_allowed_stack_size=256K
--FILE--
<?php

$a = [];
$b = [];

for ($i = 0; $i < 20000; $i++) {
$a = [$a];
$b = [$b];
}

try {
var_dump($a == $b);
} catch (Error $e) {
echo $e->getMessage(), PHP_EOL;
}

try {
var_dump($a === $b);
} catch (Error $e) {
echo $e->getMessage(), PHP_EOL;
}

?>
--EXPECT--
Maximum call stack size reached during array comparison
Maximum call stack size reached during array comparison
19 changes: 17 additions & 2 deletions Zend/zend_operators.c
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Expand Up @@ -2417,8 +2417,16 @@ ZEND_API bool ZEND_FASTCALL zend_is_identical(const zval *op1, const zval *op2)
case IS_STRING:
return zend_string_equals(Z_STR_P(op1), Z_STR_P(op2));
case IS_ARRAY:
return (Z_ARRVAL_P(op1) == Z_ARRVAL_P(op2) ||
zend_hash_compare(Z_ARRVAL_P(op1), Z_ARRVAL_P(op2), (compare_func_t) hash_zval_identical_function, 1) == 0);
if (Z_ARRVAL_P(op1) == Z_ARRVAL_P(op2)) {
return 1;
}
#ifdef ZEND_CHECK_STACK_LIMIT
if (UNEXPECTED(zend_call_stack_overflowed(EG(stack_limit)))) {
zend_throw_error(NULL, "Maximum call stack size reached during array comparison");
return 0;
}
#endif
return zend_hash_compare(Z_ARRVAL_P(op1), Z_ARRVAL_P(op2), (compare_func_t) hash_zval_identical_function, 1) == 0;
case IS_OBJECT:
return (Z_OBJ_P(op1) == Z_OBJ_P(op2));
default:
Expand Down Expand Up @@ -3423,6 +3431,13 @@ ZEND_API int ZEND_FASTCALL zend_compare_symbol_tables(HashTable *ht1, HashTable

ZEND_API int ZEND_FASTCALL zend_compare_arrays(zval *a1, zval *a2) /* {{{ */
{
#ifdef ZEND_CHECK_STACK_LIMIT
if (UNEXPECTED(zend_call_stack_overflowed(EG(stack_limit)))) {
zend_throw_error(NULL, "Maximum call stack size reached during array comparison");
return ZEND_UNCOMPARABLE;
}
#endif

return zend_compare_symbol_tables(Z_ARRVAL_P(a1), Z_ARRVAL_P(a2));
}
/* }}} */
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