Merge branch 'PHP-8.5'

* PHP-8.5:
  Fix GH-20483: ASAN stack overflow with small fiber.stack_size INI value.

Author: devnexen

NEWS

@@ -16,6 +16,10 @@ PHP                                                                        NEWS
     with a given skeleton, locale, collapse type and identity fallback.
     (BogdanUngureanu)
 
+- Fibers:
+  . Fixed bug GH-20483 (ASAN stack overflow with fiber.stack_size INI
+    small value). (David Carlier)
+
 - Opcache:
   . Fixed bug GH-20051 (apache2 shutdowns when restart is requested during
     preloading). (Arnaud, welcomycozyhom)

Zend/tests/fibers/gh20483.phpt

@@ -0,0 +1,16 @@
+--TEST--
+GH-20483 (ASAN stack overflow with small fiber.stack_size INI value)
+--INI--
+fiber.stack_size=1024
+--FILE--
+<?php
+$callback = function () {};
+$fiber = new Fiber($callback);
+try {
+    $fiber->start();
+} catch (Exception $e) {
+    echo $e->getMessage() . "\n";
+}
+?>
+--EXPECTF--
+Fiber stack size is too small, it needs to be at least %d bytes

Zend/zend_fibers.c

@@ -207,7 +207,12 @@ static zend_fiber_stack *zend_fiber_stack_allocate(size_t size)
 {
 	void *pointer;
 	const size_t page_size = zend_fiber_get_page_size();
-	const size_t minimum_stack_size = page_size + ZEND_FIBER_GUARD_PAGES * page_size;
+	const size_t minimum_stack_size = page_size + ZEND_FIBER_GUARD_PAGES * page_size
+#ifdef __SANITIZE_ADDRESS__
+	// necessary correction due to ASAN redzones
+	* 6
+#endif
+	;
 
 	if (size < minimum_stack_size) {
 		zend_throw_exception_ex(NULL, 0, "Fiber stack size is too small, it needs to be at least %zu bytes", minimum_stack_size);