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alexandre-dauboisalexandre-daubois
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Fix GH-16649: Avoid UAF when using array_splice
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‎NEWS

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Original file line numberDiff line numberDiff line change
@@ -73,6 +73,7 @@ PHP NEWS
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. Fix theoretical issues with hrtime() not being available. (nielsdos)
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. Fixed bug GH-19300 (Nested array_multisort invocation with error breaks).
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(nielsdos)
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. Fixed bug GH-16649 (UAF during array_splice). (alexandre-daubois)
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- Windows:
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. Free opened_path when opened_path_len >= MAXPATHLEN. (dixyes)

‎ext/standard/array.c

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@@ -3214,6 +3214,9 @@ static void php_splice(HashTable *in_hash, zend_long offset, zend_long length, H
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zval *entry; /* Hash entry */
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uint32_t iter_pos = zend_hash_iterators_lower_pos(in_hash, 0);
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GC_ADDREF(in_hash);
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HT_ALLOW_COW_VIOLATION(in_hash); /* Will be reset when setting the flags for in_hash */
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/* Get number of entries in the input hash */
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num_in = zend_hash_num_elements(in_hash);
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@@ -3372,6 +3375,15 @@ static void php_splice(HashTable *in_hash, zend_long offset, zend_long length, H
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HT_SET_ITERATORS_COUNT(&out_hash, HT_ITERATORS_COUNT(in_hash));
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HT_SET_ITERATORS_COUNT(in_hash, 0);
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in_hash->pDestructor = NULL;
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if (UNEXPECTED(GC_DELREF(in_hash) == 0)) {
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/* Array was completely deallocated during the operation */
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zend_array_destroy(in_hash);
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zend_hash_destroy(&out_hash);
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zend_throw_error(NULL, "Array was modified during array_splice operation");
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return;
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}
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zend_hash_destroy(in_hash);
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HT_FLAGS(in_hash) = HT_FLAGS(&out_hash);

‎ext/standard/tests/array/gh16649/array_splice_normal_destructor.phpt

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@@ -0,0 +1,20 @@
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--TEST--
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GH-16649: array_splice with normal destructor should work fine
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--FILE--
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<?php
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class C {
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function __destruct() {
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echo "Destructor called\n";
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}
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}
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$arr = ["1", new C, "2"];
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array_splice($arr, 1, 2);
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var_dump($arr);
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?>
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--EXPECT--
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Destructor called
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array(1) {
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[0]=>
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string(1) "1"
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}

‎ext/standard/tests/array/gh16649/array_splice_uaf_add_elements.phpt

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Original file line numberDiff line numberDiff line change
@@ -0,0 +1,22 @@
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--TEST--
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GH-16649: array_splice UAF when destructor adds elements to array
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--FILE--
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<?php
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class C {
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function __destruct() {
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global $arr;
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$arr[] = 0;
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}
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}
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$arr = ["1", new C, "2"];
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try {
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array_splice($arr, 1, 2);
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echo "ERROR: Should have thrown exception\n";
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} catch (Error $e) {
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echo "Exception caught: " . $e->getMessage() . "\n";
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}
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?>
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--EXPECT--
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Exception caught: Array was modified during array_splice operation

‎ext/standard/tests/array/gh16649/array_splice_uaf_array_deallocated.phpt

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Original file line numberDiff line numberDiff line change
@@ -0,0 +1,22 @@
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--TEST--
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GH-16649: array_splice UAF when array is released entirely
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--FILE--
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<?php
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class C {
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function __destruct() {
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global $arr;
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$arr = null;
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}
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}
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$arr = ["1", new C, "2"];
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try {
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array_splice($arr, 1, 2);
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echo "ERROR: Should have thrown exception\n";
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} catch (Error $e) {
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echo "Exception caught: " . $e->getMessage() . "\n";
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}
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?>
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--EXPECT--
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Exception caught: Array was modified during array_splice operation

‎ext/standard/tests/array/gh16649/array_splice_uaf_complex_modification.phpt

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--TEST--
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GH-16649: array_splice UAF with complex array modification
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--FILE--
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<?php
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class ComplexModifier {
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function __destruct() {
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global $arr;
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// complex modification that causes cow
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unset($arr[0]);
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$arr["new_key"] = "new_value";
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$arr[100] = "another_value";
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}
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}
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$arr = ["first", new ComplexModifier, "last"];
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try {
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array_splice($arr, 1, 1, ["replacement"]);
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echo "ERROR: Should have thrown exception\n";
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} catch (Error $e) {
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echo "Exception caught: " . $e->getMessage() . "\n";
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}
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?>
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--EXPECT--
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Exception caught: Array was modified during array_splice operation

‎ext/standard/tests/array/gh16649/array_splice_uaf_multiple_destructors.phpt

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@@ -0,0 +1,33 @@
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--TEST--
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GH-16649: array_splice UAF with multiple destructors
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--FILE--
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<?php
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class MultiDestructor {
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public $id;
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function __construct($id) {
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$this->id = $id;
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}
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function __destruct() {
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global $arr;
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echo "Destructor {$this->id} called\n";
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if ($this->id == 2) {
16+
$arr = null;
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}
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}
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}
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$arr = ["start", new MultiDestructor(1), new MultiDestructor(2), "end"];
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try {
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array_splice($arr, 1, 2);
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echo "ERROR: Should have thrown exception\n";
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} catch (Error $e) {
27+
echo "Exception caught: " . $e->getMessage() . "\n";
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}
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?>
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--EXPECT--
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Destructor 1 called
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Destructor 2 called
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Exception caught: Array was modified during array_splice operation

‎ext/standard/tests/array/gh16649/array_splice_uaf_original_case.phpt

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@@ -0,0 +1,29 @@
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--TEST--
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GH-16649: array_splice UAF with destructor modifying array (original case)
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--FILE--
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<?php
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function resize_arr() {
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global $arr;
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for ($i = 0; $i < 10; $i++) {
8+
$arr[$i] = $i;
9+
}
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}
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class C {
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function __destruct() {
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resize_arr();
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return "3";
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}
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}
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19+
$arr = ["a" => "1", "3" => new C, "2" => "2"];
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21+
try {
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array_splice($arr, 1, 2);
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echo "ERROR: Should have thrown exception\n";
24+
} catch (Error $e) {
25+
echo "Exception caught: " . $e->getMessage() . "\n";
26+
}
27+
?>
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--EXPECT--
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Exception caught: Array was modified during array_splice operation

‎ext/standard/tests/array/gh16649/array_splice_uaf_packed_to_hash.phpt

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Original file line numberDiff line numberDiff line change
@@ -0,0 +1,23 @@
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--TEST--
2+
GH-16649: array_splice UAF when array is converted from packed to hash
3+
--FILE--
4+
<?php
5+
class C {
6+
function __destruct() {
7+
global $arr;
8+
// array is converted from packed to hash
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$arr["str"] = 0;
10+
}
11+
}
12+
13+
$arr = ["1", new C, "2"];
14+
15+
try {
16+
array_splice($arr, 1, 2);
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echo "ERROR: Should have thrown exception\n";
18+
} catch (Error $e) {
19+
echo "Exception caught: " . $e->getMessage() . "\n";
20+
}
21+
?>
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--EXPECT--
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Exception caught: Array was modified during array_splice operation

‎ext/standard/tests/array/gh16649/array_splice_with_replacement.phpt

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@@ -0,0 +1,23 @@
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--TEST--
2+
GH-16649: array_splice with replacement array when destructor modifies array
3+
--FILE--
4+
<?php
5+
class C {
6+
function __destruct() {
7+
global $arr;
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$arr["modified"] = "by_destructor";
9+
}
10+
}
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12+
$arr = ["a", new C, "b"];
13+
$replacement = ["replacement1", "replacement2"];
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15+
try {
16+
array_splice($arr, 1, 1, $replacement);
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echo "ERROR: Should have thrown exception\n";
18+
} catch (Error $e) {
19+
echo "Exception caught: " . $e->getMessage() . "\n";
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}
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?>
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--EXPECT--
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Exception caught: Array was modified during array_splice operation

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