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Fix GH-16337: Use-after-free in SplHeap #16346

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Fix GH-16337: Use-after-free in SplHeap #16346

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55 changes: 37 additions & 18 deletions ext/spl/spl_heap.c
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Original file line number Diff line number Diff line change
Expand Up @@ -32,6 +32,7 @@
#define PTR_HEAP_BLOCK_SIZE 64

#define SPL_HEAP_CORRUPTED 0x00000001
#define SPL_HEAP_WRITE_LOCKED 0x00000002

zend_object_handlers spl_handler_SplHeap;
zend_object_handlers spl_handler_SplPriorityQueue;
Expand Down Expand Up @@ -278,12 +279,16 @@ static void spl_ptr_heap_insert(spl_ptr_heap *heap, void *elem, void *cmp_userda
heap->max_size *= 2;
}

heap->flags |= SPL_HEAP_WRITE_LOCKED;

/* sifting up */
for (i = heap->count; i > 0 && heap->cmp(spl_heap_elem(heap, (i-1)/2), elem, cmp_userdata) < 0; i = (i-1)/2) {
spl_heap_elem_copy(heap, spl_heap_elem(heap, i), spl_heap_elem(heap, (i-1)/2));
}
heap->count++;

heap->flags &= ~SPL_HEAP_WRITE_LOCKED;

if (EG(exception)) {
/* exception thrown during comparison */
heap->flags |= SPL_HEAP_CORRUPTED;
Expand Down Expand Up @@ -311,6 +316,8 @@ static int spl_ptr_heap_delete_top(spl_ptr_heap *heap, void *elem, void *cmp_use
return FAILURE;
}

heap->flags |= SPL_HEAP_WRITE_LOCKED;

if (elem) {
spl_heap_elem_copy(heap, elem, spl_heap_elem(heap, 0));
} else {
Expand All @@ -334,6 +341,8 @@ static int spl_ptr_heap_delete_top(spl_ptr_heap *heap, void *elem, void *cmp_use
}
}

heap->flags &= ~SPL_HEAP_WRITE_LOCKED;

if (EG(exception)) {
/* exception thrown during comparison */
heap->flags |= SPL_HEAP_CORRUPTED;
Expand Down Expand Up @@ -374,10 +383,14 @@ static spl_ptr_heap *spl_ptr_heap_clone(spl_ptr_heap *from) { /* {{{ */
static void spl_ptr_heap_destroy(spl_ptr_heap *heap) { /* {{{ */
int i;

heap->flags |= SPL_HEAP_WRITE_LOCKED;

for (i = 0; i < heap->count; ++i) {
heap->dtor(spl_heap_elem(heap, i));
}

heap->flags &= ~SPL_HEAP_WRITE_LOCKED;

efree(heap->elements);
efree(heap);
}
Expand Down Expand Up @@ -597,6 +610,21 @@ PHP_METHOD(SplHeap, isEmpty)
}
/* }}} */

static zend_result spl_heap_consistency_validations(const spl_heap_object *intern, bool write)
{
if (intern->heap->flags & SPL_HEAP_CORRUPTED) {
zend_throw_exception(spl_ce_RuntimeException, "Heap is corrupted, heap properties are no longer ensured.", 0);
return FAILURE;
}

if (write && (intern->heap->flags & SPL_HEAP_WRITE_LOCKED)) {
zend_throw_exception(spl_ce_RuntimeException, "Heap cannot be changed when it is already being modified.", 0);
return FAILURE;
}

return SUCCESS;
}

/* {{{ Push $value on the heap */
PHP_METHOD(SplHeap, insert)
{
Expand All @@ -609,8 +637,7 @@ PHP_METHOD(SplHeap, insert)

intern = Z_SPLHEAP_P(ZEND_THIS);

if (intern->heap->flags & SPL_HEAP_CORRUPTED) {
zend_throw_exception(spl_ce_RuntimeException, "Heap is corrupted, heap properties are no longer ensured.", 0);
if (UNEXPECTED(spl_heap_consistency_validations(intern, true) != SUCCESS)) {
RETURN_THROWS();
}

Expand All @@ -632,8 +659,7 @@ PHP_METHOD(SplHeap, extract)

intern = Z_SPLHEAP_P(ZEND_THIS);

if (intern->heap->flags & SPL_HEAP_CORRUPTED) {
zend_throw_exception(spl_ce_RuntimeException, "Heap is corrupted, heap properties are no longer ensured.", 0);
if (UNEXPECTED(spl_heap_consistency_validations(intern, true) != SUCCESS)) {
RETURN_THROWS();
}

Expand All @@ -658,8 +684,7 @@ PHP_METHOD(SplPriorityQueue, insert)

intern = Z_SPLHEAP_P(ZEND_THIS);

if (intern->heap->flags & SPL_HEAP_CORRUPTED) {
zend_throw_exception(spl_ce_RuntimeException, "Heap is corrupted, heap properties are no longer ensured.", 0);
if (UNEXPECTED(spl_heap_consistency_validations(intern, true) != SUCCESS)) {
RETURN_THROWS();
}

Expand Down Expand Up @@ -699,8 +724,7 @@ PHP_METHOD(SplPriorityQueue, extract)

intern = Z_SPLHEAP_P(ZEND_THIS);

if (intern->heap->flags & SPL_HEAP_CORRUPTED) {
zend_throw_exception(spl_ce_RuntimeException, "Heap is corrupted, heap properties are no longer ensured.", 0);
if (UNEXPECTED(spl_heap_consistency_validations(intern, true) != SUCCESS)) {
RETURN_THROWS();
}

Expand All @@ -726,8 +750,7 @@ PHP_METHOD(SplPriorityQueue, top)

intern = Z_SPLHEAP_P(ZEND_THIS);

if (intern->heap->flags & SPL_HEAP_CORRUPTED) {
zend_throw_exception(spl_ce_RuntimeException, "Heap is corrupted, heap properties are no longer ensured.", 0);
if (UNEXPECTED(spl_heap_consistency_validations(intern, false) != SUCCESS)) {
RETURN_THROWS();
}

Expand Down Expand Up @@ -837,8 +860,7 @@ PHP_METHOD(SplHeap, top)

intern = Z_SPLHEAP_P(ZEND_THIS);

if (intern->heap->flags & SPL_HEAP_CORRUPTED) {
zend_throw_exception(spl_ce_RuntimeException, "Heap is corrupted, heap properties are no longer ensured.", 0);
if (UNEXPECTED(spl_heap_consistency_validations(intern, false) != SUCCESS)) {
RETURN_THROWS();
}

Expand Down Expand Up @@ -902,8 +924,7 @@ static zval *spl_heap_it_get_current_data(zend_object_iterator *iter) /* {{{ */
{
spl_heap_object *object = Z_SPLHEAP_P(&iter->data);

if (object->heap->flags & SPL_HEAP_CORRUPTED) {
zend_throw_exception(spl_ce_RuntimeException, "Heap is corrupted, heap properties are no longer ensured.", 0);
if (UNEXPECTED(spl_heap_consistency_validations(object, false) != SUCCESS)) {
return NULL;
}

Expand All @@ -920,8 +941,7 @@ static zval *spl_pqueue_it_get_current_data(zend_object_iterator *iter) /* {{{ *
zend_user_iterator *user_it = (zend_user_iterator *) iter;
spl_heap_object *object = Z_SPLHEAP_P(&iter->data);

if (object->heap->flags & SPL_HEAP_CORRUPTED) {
zend_throw_exception(spl_ce_RuntimeException, "Heap is corrupted, heap properties are no longer ensured.", 0);
if (UNEXPECTED(spl_heap_consistency_validations(object, false) != SUCCESS)) {
return NULL;
}

Expand Down Expand Up @@ -949,8 +969,7 @@ static void spl_heap_it_move_forward(zend_object_iterator *iter) /* {{{ */
{
spl_heap_object *object = Z_SPLHEAP_P(&iter->data);

if (object->heap->flags & SPL_HEAP_CORRUPTED) {
zend_throw_exception(spl_ce_RuntimeException, "Heap is corrupted, heap properties are no longer ensured.", 0);
if (UNEXPECTED(spl_heap_consistency_validations(object, false) != SUCCESS)) {
return;
}

Expand Down
49 changes: 49 additions & 0 deletions ext/spl/tests/gh16337.phpt
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Original file line number Diff line number Diff line change
@@ -0,0 +1,49 @@
--TEST--
GH-16337 (Use-after-free in SplHeap)
--FILE--
<?php

class C {
function __toString() {
global $heap;
try {
$heap->extract();
} catch (Throwable $e) {
echo $e->getMessage(), "\n";
}
try {
$heap->insert(1);
} catch (Throwable $e) {
echo $e->getMessage(), "\n";
}
echo $heap->top(), "\n";
return "0";
}
}

$heap = new SplMinHeap;
for ($i = 0; $i < 100; $i++) {
$heap->insert((string) $i);
}
$heap->insert(new C);

?>
--EXPECT--
Heap cannot be changed when it is already being modified.
Heap cannot be changed when it is already being modified.
0
Heap cannot be changed when it is already being modified.
Heap cannot be changed when it is already being modified.
0
Heap cannot be changed when it is already being modified.
Heap cannot be changed when it is already being modified.
0
Heap cannot be changed when it is already being modified.
Heap cannot be changed when it is already being modified.
0
Heap cannot be changed when it is already being modified.
Heap cannot be changed when it is already being modified.
0
Heap cannot be changed when it is already being modified.
Heap cannot be changed when it is already being modified.
0
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