Fix uncatchable exception thrown in generator

This procedure may be called during i_free_compiled_variables(), when
EG(current_execute_data) is unfortunately already reset to the parent frame.
EG(opline_before_exception) does not actually belong to this frame. Furthermore,
setting opline to EG(exception_op) early will miss a later
zend_rethrow_exception(), which will also miss installation of the correct
EG(opline_before_exception).

Fixes GH-20714

Author: iluuu1994

Zend/tests/gh20714.phpt

@@ -0,0 +1,29 @@
+--TEST--
+GH-20714: Uncatchable exception thrown in generator
+--FILE--
+<?php
+
+function gen(): Generator
+{
+    try {
+        yield 1;
+    } finally {}
+}
+
+function process(): void
+{
+    $g = gen();
+    foreach ($g as $_) {
+        throw new Exception('ERROR');
+    }
+}
+
+try {
+    process();
+} catch (Exception $e) {
+    echo "Caught\n";
+}
+
+?>
+--EXPECT--
+Caught

Zend/zend_generators.c

@@ -321,7 +321,9 @@ static void zend_generator_dtor_storage(zend_object *object) /* {{{ */
 			zend_object *old_exception = NULL;
 			const zend_op *old_opline_before_exception = NULL;
 			if (EG(exception)) {
-				if (EG(current_execute_data)) {
+				if (EG(current_execute_data)
+				 && EG(current_execute_data)->opline
+				 && EG(current_execute_data)->opline->opcode == ZEND_HANDLE_EXCEPTION) {
 					EG(current_execute_data)->opline = EG(opline_before_exception);
 					old_opline_before_exception = EG(opline_before_exception);
 				}
@@ -337,7 +339,7 @@ static void zend_generator_dtor_storage(zend_object *object) /* {{{ */
 			zend_generator_resume(generator);
 
 			if (old_exception) {
-				if (EG(current_execute_data)) {
+				if (old_opline_before_exception) {
 					EG(current_execute_data)->opline = EG(exception_op);
 					EG(opline_before_exception) = old_opline_before_exception;
 				}