From 429f194f406e8d8255a12af210aa4bde3f9e1433 Mon Sep 17 00:00:00 2001
From: Nikita Popov <nikita.ppv@gmail.com>
Date: Thu, 30 Jan 2020 11:01:13 +0100
Subject: [PATCH] Fix UAF in is_callable() and allocated trampoline

By nulling out the function_handler, so it will not get used
below. Reuse the existing helper for this purpose.
---
 Zend/tests/is_callable_trampoline_uaf.phpt | 27 ++++++++++++++++++++++
 Zend/zend_API.c                            |  8 +------
 2 files changed, 28 insertions(+), 7 deletions(-)
 create mode 100644 Zend/tests/is_callable_trampoline_uaf.phpt

diff --git a/Zend/tests/is_callable_trampoline_uaf.phpt b/Zend/tests/is_callable_trampoline_uaf.phpt
new file mode 100644
index 0000000000..2410864410
--- /dev/null
+++ b/Zend/tests/is_callable_trampoline_uaf.phpt
@@ -0,0 +1,27 @@
+--TEST--
+is_callable() with trampoline should not caused UAF
+--FILE--
+<?php
+
+class B {}
+class A extends B {
+    public function bar($func) {
+        var_dump(is_callable(array('parent', 'foo')));
+    }
+
+    public function __call($func, $args) {
+    }
+}
+
+class X {
+    public static function __callStatic($func, $args) {
+    }
+}
+
+$a = new A();
+// Extra X::foo() wrapper to force use of allocated trampoline.
+X::foo($a->bar('foo'));
+
+?>
+--EXPECT--
+bool(false)
diff --git a/Zend/zend_API.c b/Zend/zend_API.c
index 4511368bea..b7af44a32a 100644
--- a/Zend/zend_API.c
+++ b/Zend/zend_API.c
@@ -3154,13 +3154,7 @@ get_function_via_handler:
 					if (strict_class &&
 					    (!fcc->function_handler->common.scope ||
 					     !instanceof_function(ce_org, fcc->function_handler->common.scope))) {
-						if (fcc->function_handler->common.fn_flags & ZEND_ACC_CALL_VIA_TRAMPOLINE) {
-							if (fcc->function_handler->type != ZEND_OVERLOADED_FUNCTION &&
-								fcc->function_handler->common.function_name) {
-								zend_string_release_ex(fcc->function_handler->common.function_name, 0);
-							}
-							zend_free_trampoline(fcc->function_handler);
-						}
+						zend_release_fcall_info_cache(fcc);
 					} else {
 						retval = 1;
 						call_via_handler = (fcc->function_handler->common.fn_flags & ZEND_ACC_CALL_VIA_TRAMPOLINE) != 0;
-- 
2.49.0