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Fix use-after-free in Randomizer::shuffleArray() when the engine throws #24553

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Fix use-after-free in Randomizer::shuffleArray() when the engine throws #24553

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b86b0b7
Fix use-after-free in Randomizer::shuffleArray() when the engine throws
Marti2203 Oct 22, 2026
5af1208
Reset hash counters right after compaction in php_array_data_shuffle()
Marti2203 Oct 24, 2026
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61 changes: 61 additions & 0 deletions ext/random/tests/03_randomizer/methods/shuffleArray_engine_throws_with_holes.phpt
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Original file line number Diff line number Diff line change
@@ -0,0 +1,61 @@
--TEST--
Random: Randomizer: shuffleArray(): Engine throwing on an array with holes
--FILE--
<?php

use Random\Engine;
use Random\Randomizer;

final class ThrowingEngine implements Engine
{
public function __construct(private int $calls) {}

public function generate(): string
{
if ($this->calls-- <= 0) {
throw new Exception('Error');
}

return "\x01\x00\x00\x00\x00\x00\x00\x00";
}
}

foreach ([0, 1] as $calls) {
$array = [new stdClass, new stdClass, new stdClass, new stdClass];
unset($array[1]);

try {
(new Randomizer(new ThrowingEngine($calls)))->shuffleArray($array);
} catch (Exception $e) {
echo $e->getMessage(), PHP_EOL;
}

var_dump($array);
}

?>
--EXPECTF--
Error
array(3) {
[0]=>
object(stdClass)#%d (0) {
}
[2]=>
object(stdClass)#%d (0) {
}
[3]=>
object(stdClass)#%d (0) {
}
}
Error
array(3) {
[0]=>
object(stdClass)#%d (0) {
}
[2]=>
object(stdClass)#%d (0) {
}
[3]=>
object(stdClass)#%d (0) {
}
}
10 changes: 7 additions & 3 deletions ext/standard/array.c
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Original file line number Diff line number Diff line change
Expand Up @@ -3302,6 +3302,10 @@ PHPAPI bool php_array_data_shuffle(php_random_algo_with_state engine, zval *arra
j++;
}
}
/* Truncate the stale slots left by compaction before the engine can throw. */
hash->nNumUsed = n_elems;
hash->nInternalPointer = 0;
hash->nNextFreeElement = n_elems;
while (--n_left) {
rnd_idx = algo->range(state, 0, n_left);
if (EG(exception)) {
Expand Down Expand Up @@ -3330,6 +3334,9 @@ PHPAPI bool php_array_data_shuffle(php_random_algo_with_state engine, zval *arra
j++;
}
}
hash->nNumUsed = n_elems;
hash->nInternalPointer = 0;
hash->nNextFreeElement = n_elems;
while (--n_left) {
rnd_idx = algo->range(state, 0, n_left);
if (EG(exception)) {
Expand All @@ -3343,9 +3350,6 @@ PHPAPI bool php_array_data_shuffle(php_random_algo_with_state engine, zval *arra
}
}
}
hash->nNumUsed = n_elems;
hash->nInternalPointer = 0;
hash->nNextFreeElement = n_elems;

return true;
}
Expand Down
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