[php-src] master: Merge branch 'PHP-8.5'

Author: ndossche (ndossche)
Date: 2026-08-05T10:30:47+02:00

Commit: https://github.com/php/php-src/commit/be6fa2bc48ff46dd36e168b2339b8fda7e57021b
Raw diff: https://github.com/php/php-src/commit/be6fa2bc48ff46dd36e168b2339b8fda7e57021b.diff

Merge branch 'PHP-8.5'

* PHP-8.5:
  Fix GH-23043: broken session id code can cause zend_mm_heap corrupted
  session: fix corruption in mod_mm

Changed paths:
  A  ext/session/tests/user_session_module/gh23043.phpt
  M  ext/session/session.c


Diff:

diff --git a/ext/session/session.c b/ext/session/session.c
index dd968d453bda..257eec002392 100644
--- a/ext/session/session.c
+++ b/ext/session/session.c
@@ -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), false);
+			PS(id) = NULL;
 		}
 		PS(id) = PS(mod)->s_create_sid(&PS(mod_data));
 		if (!PS(id)) {
@@ -458,7 +459,10 @@ static zend_result php_session_initialize(void)
 	} else if (PS(use_strict_mode) && PS(mod)->s_validate_sid &&
 		PS(mod)->s_validate_sid(&PS(mod_data), PS(id)) == FAILURE
 	) {
-		zend_string_release_ex(PS(id), false);
+		if (PS(id)) {
+			zend_string_release_ex(PS(id), false);
+			PS(id) = NULL;
+		}
 		PS(id) = PS(mod)->s_create_sid(&PS(mod_data));
 		if (!PS(id)) {
 			PS(id) = php_session_create_id(NULL);
@@ -2419,6 +2423,7 @@ 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), false);
+				PS(id) = NULL;
 				PS(id) = PS(mod)->s_create_sid(&PS(mod_data));
 				if (!PS(id)) {
 					PS(mod)->s_close(&PS(mod_data));
diff --git a/ext/session/tests/user_session_module/gh23043.phpt b/ext/session/tests/user_session_module/gh23043.phpt
new file mode 100644
index 000000000000..dc3676993903
--- /dev/null
+++ b/ext/session/tests/user_session_module/gh23043.phpt
@@ -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: ) 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: ) in Unknown on line 0