Skip to content

Fix GH-20856: heap-use-after-free in SplDoublyLinkedList iterator when modifying during iteration #20885

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
ndossche wants to merge 1 commit into
base: PHP-8.4
Choose a base branch
from
+31 −2
Open

Fix GH-20856: heap-use-after-free in SplDoublyLinkedList iterator when modifying during iteration #20885

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
7 changes: 5 additions & 2 deletions ext/spl/spl_dllist.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -764,11 +764,10 @@ PHP_METHOD(SplDoublyLinkedList, offsetUnset)
element = spl_ptr_llist_offset(intern->llist, index, intern->flags & SPL_DLLIST_IT_LIFO);

if (element != NULL) {
/* connect the neightbors */
/* disconnect the neighbours */
if (element->prev) {
element->prev->next = element->next;
}

if (element->next) {
element->next->prev = element->prev;
}
Expand All @@ -782,6 +781,10 @@ PHP_METHOD(SplDoublyLinkedList, offsetUnset)
llist->tail = element->prev;
}

/* Keep consistency if element is kept alive. */
element->prev = NULL;
element->next = NULL;

/* finally, delete the element */
llist->count--;

Expand Down
26 changes: 26 additions & 0 deletions ext/spl/tests/gh20856.phpt
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,26 @@
--TEST--
GH-20856 (heap-use-after-free in SplDoublyLinkedList iterator when modifying during iteration)
--CREDITS--
vi3tL0u1s
iluuu1994
--FILE--
<?php
$m = new SplStack;
$m[] = new stdClass;
$m[] = new stdClass;

foreach ($m as $l) {
unset($m[0]);
unset($m[0]);
}

var_dump($m);
?>
--EXPECTF--
object(SplStack)#%d (%d) {
["flags":"SplDoublyLinkedList":private]=>
int(6)
["dllist":"SplDoublyLinkedList":private]=>
array(0) {
}
}
Loading