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GH-23043: broken session id code can cause zend_mm_heap corrupted #23046

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GH-23043: broken session id code can cause zend_mm_heap corrupted #23046

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eb168c6
session: fix corruption in mod_mm
ndossche Aug 4, 2026
0d6e73c
Fix GH-23043: broken session id code can cause zend_mm_heap corrupted
ndossche Aug 4, 2026
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2 changes: 1 addition & 1 deletion ext/session/mod_mm.c
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Original file line number Diff line number Diff line change
Expand Up @@ -351,7 +351,7 @@ PS_READ_FUNC(mm)
&& ps_mm_key_exists(data, key) == FAILURE) {
/* key points to PS(id), but cannot change here. */
if (key) {
efree(PS(id));
zend_string_release_ex(PS(id), false);
PS(id) = NULL;
}
PS(id) = PS(mod)->s_create_sid((void **)&data);
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3 changes: 3 additions & 0 deletions ext/session/session.c
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Expand Up @@ -443,6 +443,7 @@ static zend_result php_session_initialize(void) /* {{{ */
if (!PS(id) || !ZSTR_VAL(PS(id))[0]) {
if (PS(id)) {
zend_string_release_ex(PS(id), 0);
PS(id) = NULL;
}
PS(id) = PS(mod)->s_create_sid(&PS(mod_data));
if (!PS(id)) {
Expand All @@ -460,6 +461,7 @@ static zend_result php_session_initialize(void) /* {{{ */
) {
if (PS(id)) {
zend_string_release_ex(PS(id), 0);
PS(id) = NULL;
}
PS(id) = PS(mod)->s_create_sid(&PS(mod_data));
if (!PS(id)) {
Expand Down Expand Up @@ -2440,6 +2442,7 @@ PHP_FUNCTION(session_regenerate_id)
/* Try to generate non-existing ID */
while (limit-- && PS(mod)->s_validate_sid(&PS(mod_data), PS(id)) == SUCCESS) {
zend_string_release_ex(PS(id), 0);
PS(id) = NULL;
PS(id) = PS(mod)->s_create_sid(&PS(mod_data));
if (!PS(id)) {
PS(mod)->s_close(&PS(mod_data));
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35 changes: 35 additions & 0 deletions ext/session/tests/user_session_module/gh23043.phpt
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Original file line number Diff line number Diff line change
@@ -0,0 +1,35 @@
--TEST--
GH-23043 (broken session id code can cause zend_mm_heap corrupted)
--EXTENSIONS--
session
--CREDITS--
lmaltsis
--FILE--
<?php
ob_start();
class a extends SessionHandler {
function read($b): string {
return "";
}
function create_sid(): string {
var_dump(session_id());
return '';
}
}
$c = new a;
session_set_save_handler($c);
session_start();
session_write_close();
session_start();
?>
--EXPECTF--
string(0) ""

Warning: SessionHandler::write(): Session ID is too long or contains illegal characters. Only the A-Z, a-z, 0-9, "-", and "," characters are allowed in %s on line %d

Warning: session_write_close(): Failed to write session data using user defined save handler. (session.save_path: , handler: a::write) in %s on line %d
string(0) ""

Warning: SessionHandler::write(): Session ID is too long or contains illegal characters. Only the A-Z, a-z, 0-9, "-", and "," characters are allowed in Unknown on line 0

Warning: session_write_close(): Failed to write session data using user defined save handler. (session.save_path: , handler: a::write) in Unknown on line 0
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