Skip to content

Fix #24763: Clear libxml entity loader before destroying FCC #24764

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
thediex wants to merge 1 commit into
base: master
Choose a base branch
from
+84 −5
Open

Fix #24763: Clear libxml entity loader before destroying FCC #24764

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
18 changes: 13 additions & 5 deletions ext/libxml/libxml.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -1041,7 +1041,10 @@ static PHP_RINIT_FUNCTION(libxml)
static PHP_RSHUTDOWN_FUNCTION(libxml)
{
if (ZEND_FCC_INITIALIZED(LIBXML(entity_loader_callback))) {
zend_fcc_dtor(&LIBXML(entity_loader_callback));
/* Detach before destruction, as destroying the callback may bail out. */
zend_fcall_info_cache old_fcc = LIBXML(entity_loader_callback);
LIBXML(entity_loader_callback) = empty_fcall_info_cache;
zend_fcc_dtor(&old_fcc);
}

return SUCCESS;
Expand Down Expand Up @@ -1261,13 +1264,18 @@ PHP_FUNCTION(libxml_set_external_entity_loader)
Z_PARAM_FUNC_NO_TRAMPOLINE_FREE_OR_NULL(fci, fcc)
ZEND_PARSE_PARAMETERS_END();

/* Unset old callback if it's defined */
if (ZEND_FCC_INITIALIZED(LIBXML(entity_loader_callback))) {
zend_fcc_dtor(&LIBXML(entity_loader_callback));
}
/* Detach the old callback before destruction, which may re-enter this function. */
zend_fcall_info_cache old_fcc = LIBXML(entity_loader_callback);
LIBXML(entity_loader_callback) = empty_fcall_info_cache;

if (ZEND_FCI_INITIALIZED(fci)) { /* argument not null */
zend_fcc_dup(&LIBXML(entity_loader_callback), &fcc);
}

/* Destroy only after installing the replacement so re-entrant changes are preserved. */
if (ZEND_FCC_INITIALIZED(old_fcc)) {
zend_fcc_dtor(&old_fcc);
}
RETURN_TRUE;
}
/* }}} */
Expand Down
38 changes: 38 additions & 0 deletions ext/libxml/tests/libxml_entity_loader_bailout.phpt
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,38 @@
--TEST--
GH-24763: libxml external entity loader is detached before callback destruction bailout
--EXTENSIONS--
libxml
zend_test
--FILE--
<?php

class Bailout
{
public function __destruct()
{
zend_trigger_bailout();
}
}

$bailout = new Bailout();

$loader = function () use ($bailout) {
};

unset($bailout);

register_shutdown_function(function () {
var_dump(libxml_get_external_entity_loader());
});

libxml_set_external_entity_loader($loader);
unset($loader);

libxml_set_external_entity_loader(null);

echo "UNREACHABLE\n";

?>
--EXPECTF--
Fatal error: Bailout in %s on line %d
NULL
33 changes: 33 additions & 0 deletions ext/libxml/tests/libxml_entity_loader_reentrant_replace.phpt
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,33 @@
--TEST--
libxml external entity loader replacement is safe against destructor reentrancy
--EXTENSIONS--
libxml
--FILE--
<?php

class D
{
public function __destruct()
{
libxml_set_external_entity_loader(fn() => null);
}
}

$d = new D();

$oldLoader = function () use ($d) {
};

unset($d);

libxml_set_external_entity_loader($oldLoader);
unset($oldLoader);

libxml_set_external_entity_loader(fn() => 1);

$loader = libxml_get_external_entity_loader();
var_dump($loader());

?>
--EXPECT--
NULL
Loading