Fix GH-13931: Applying zero offset to null pointer in Zend/zend_opcode.c

In the test cases, the compiler bails out due to a fatal error.
The data structures used by the compiler will contain stale values.
In particular, for the test case CG(loop_var_stack) will contain data.
The next compilation will incorrectly use elements from the previous
stack.
To solve this, we reset part of the compiler data structures.
We don't do a full re-initialization via init_compiler() because that will
also reset streams and resources.

Closes GH-13938.

NEWS

@@ -5,6 +5,8 @@ PHP                                                                        NEWS
 - Core:
   . Fixed bug GH-13772 (Invalid execute_data->opline pointers in observer fcall
     handlers when JIT is enabled). (Bob)
+  . Fixed bug GH-13931 (Applying zero offset to null pointer in
+    Zend/zend_opcode.c). (nielsdos)
 
 - Fibers:
   . Fixed bug GH-13903 (ASAN false positive underflow when executing copy()).

Zend/tests/gh13931.phpt

@@ -0,0 +1,23 @@
+--TEST--
+GH-13931 (Applying zero offset to null pointer in Zend/zend_opcode.c)
+--FILE--
+<?php
+
+register_shutdown_function(function() {
+	var_dump(eval("return 1+3;"));
+});
+
+eval(<<<EVAL
+function foo () {
+    try {
+        break;
+    } finally {
+    }
+}
+foo();
+EVAL);
+
+?>
+--EXPECTF--
+Fatal error: 'break' not in the 'loop' or 'switch' context in %s on line %d
+int(4)

main/main.c

@@ -1405,6 +1405,14 @@ static ZEND_COLD void php_error_cb(int orig_type, zend_string *error_filename, c
 					/* restore memory limit */
 					zend_set_memory_limit(PG(memory_limit));
 					zend_objects_store_mark_destructed(&EG(objects_store));
+					if (CG(in_compilation) && (type == E_COMPILE_ERROR || type == E_PARSE)) {
+						/* We bailout during compilation which may for example leave stale entries in CG(loop_var_stack).
+						 * If code is compiled during shutdown, we need to make sure the compiler is reset to a clean state,
+						 * otherwise this will lead to incorrect compilation during shutdown.
+						 * We don't do a full re-initialization via init_compiler() because that will also reset streams and resources. */
+						shutdown_compiler();
+						zend_init_compiler_data_structures();
+					}
 					zend_bailout();
 					return;
 				}

sapi/phpdbg/tests/gh13931.phpt

@@ -0,0 +1,21 @@
+--TEST--
+Applying zero offset to null pointer in Zend/zend_opcode.c
+--FILE--
+<?php
+function foo () {
+    try {
+        break;
+    } finally {
+    }
+}
+foo();
+?>
+--PHPDBG--
+ev 1 + 3
+ev 2 ** 3
+q
+--EXPECTF--
+Fatal error: 'break' not in the 'loop' or 'switch' context in %s on line %d
+prompt> 4
+prompt> 8
+prompt>