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Fix GH-16054: Segmentation fault when resizing hash table iterator list while adding #16060

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Fix GH-16054: Segmentation fault when resizing hash table iterator list while adding #16060

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Fix GH-16054: Segmentation fault when resizing hash table iterator li…
nielsdos Sep 25, 2024
c6c2941
Use indices
nielsdos Sep 25, 2024
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7 changes: 6 additions & 1 deletion Zend/zend_hash.c
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Original file line number Diff line number Diff line change
Expand Up @@ -2347,11 +2347,16 @@ static zend_always_inline bool zend_array_dup_element(HashTable *source, HashTab
// We need to duplicate iterators to be able to search through all copy-on-write copies to find the actually iterated HashTable and position back
static void zend_array_dup_ht_iterators(HashTable *source, HashTable *target) {
HashTableIterator *iter = EG(ht_iterators);
HashTableIterator *end = iter + EG(ht_iterators_used);
uint32_t nr_iterators_used = EG(ht_iterators_used);
HashTableIterator *end = iter + nr_iterators_used;

while (iter != end) {
if (iter->ht == source) {
size_t iter_index = iter - EG(ht_iterators);
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Alternative idea is to use indices in the while loop, but then we have to fetch EG(ht_iterators) always in the loop body which seemed more expensive.

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I think indices are going to be better.

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Ok I have pushed a commit to do that.

uint32_t copy_idx = zend_hash_iterator_add(target, iter->pos);
/* Refetch iter and recompute end because the memory may be reallocated. */
end = EG(ht_iterators) + nr_iterators_used;
iter = &EG(ht_iterators)[iter_index];
HashTableIterator *copy_iter = EG(ht_iterators) + copy_idx;
copy_iter->next_copy = iter->next_copy;
iter->next_copy = copy_idx;
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15 changes: 15 additions & 0 deletions ext/spl/tests/gh16054.phpt
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@@ -0,0 +1,15 @@
--TEST--
GH-16054 (Segmentation fault when resizing hash table iterator list while adding)
--FILE--
<?php
$multi_array = ['zero'];
$multi_array[] =& $multi_array;
$it = new RecursiveTreeIterator(new RecursiveArrayIterator($multi_array), 0);
$counter = 0;
foreach ($it as $k => $v) {
if (++$counter > 200) break;
}
echo "ok\n";
?>
--EXPECT--
ok
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