From 094e1a8b2def767b41d2defaf7cb86681126f9da Mon Sep 17 00:00:00 2001
From: Dmitry Stogov <dmitry@zend.com>
Date: Tue, 26 Jan 2021 18:41:26 +0300
Subject: [PATCH] Skip dummy frames allocated on CPU stack of
 zend_call_function(). (Usage of "current_observed_frame" varible looks unsafe
 to me).

---
 Zend/zend_observer.c                       |  8 +++--
 ext/zend_test/tests/observer_error_05.phpt | 35 ++++++++++++++++++++++
 2 files changed, 41 insertions(+), 2 deletions(-)
 create mode 100644 ext/zend_test/tests/observer_error_05.phpt

diff --git a/Zend/zend_observer.c b/Zend/zend_observer.c
index a8ce1eb5c0..a60428ee04 100644
--- a/Zend/zend_observer.c
+++ b/Zend/zend_observer.c
@@ -220,7 +220,11 @@ ZEND_API void ZEND_FASTCALL zend_observer_fcall_end(
 		first_observed_frame = NULL;
 		current_observed_frame = NULL;
 	} else {
-		current_observed_frame = execute_data->prev_execute_data;
+		zend_execute_data *ex = execute_data->prev_execute_data;
+		while (ex && !ex->func) {
+			ex = ex->prev_execute_data;
+		}
+		current_observed_frame = ex;
 	}
 }
 
@@ -228,7 +232,7 @@ ZEND_API void zend_observer_fcall_end_all(void)
 {
 	zend_execute_data *ex = current_observed_frame;
 	while (ex != NULL) {
-		if (ex->func->type != ZEND_INTERNAL_FUNCTION) {
+		if (ex->func && ex->func->type != ZEND_INTERNAL_FUNCTION) {
 			zend_observer_fcall_end(ex, NULL);
 		}
 		ex = ex->prev_execute_data;
diff --git a/ext/zend_test/tests/observer_error_05.phpt b/ext/zend_test/tests/observer_error_05.phpt
new file mode 100644
index 0000000000..d3e5f67a4e
--- /dev/null
+++ b/ext/zend_test/tests/observer_error_05.phpt
@@ -0,0 +1,35 @@
+--TEST--
+Observer: End handlers fire after a userland fatal error
+--SKIPIF--
+<?php if (!extension_loaded('zend-test')) die('skip: zend-test extension required'); ?>
+--INI--
+zend_test.observer.enabled=1
+zend_test.observer.observe_all=1
+zend_test.observer.show_return_value=1
+--FILE--
+<?php
+set_error_handler(function ($errno, $errstr, $errfile, $errline) {
+    trigger_error('Foo error', E_USER_ERROR);
+});
+
+function foo()
+{
+	return $x; // warning
+}
+
+foo();
+
+echo 'You should not see this.';
+?>
+--EXPECTF--
+<!-- init '%s%eobserver_error_%d.php' -->
+<file '%s%eobserver_error_%d.php'>
+  <!-- init foo() -->
+  <foo>
+    <!-- init {closure}() -->
+    <{closure}>
+
+Fatal error: Foo error in %s on line %d
+    </{closure}:NULL>
+  </foo:NULL>
+</file '%s%eobserver_error_%d.php'>
-- 
2.40.0