Fix bug #66182 exit in stream filter produces segfault

Unfortunately, a segv caused by exit cannot be tested reliably.

Author: m6w6

NEWS

@@ -6,6 +6,7 @@ PHP                                                                        NEWS
   . Fixed bug #61019 (Out of memory on command stream_get_contents). (Mike)
   . Fixed bug #64330 (stream_socket_server() creates wrong Abstract Namespace 
     UNIX sockets). (Mike)
+  . Fixed bug #66182 (exit in stream filter produces segfault). (Mike)
 
 - Embed:
   . Fixed bug #65715 (php5embed.lib isn't provided anymore). (Anatol)

ext/standard/user_filters.c

@@ -180,6 +180,11 @@ php_stream_filter_status_t userfilter_filter(
 	zval zpropname;
 	int call_result;
 
+	/* the userfilter object probably doesn't exist anymore */
+	if (CG(unclean_shutdown)) {
+		return ret;
+	}
+
 	if (FAILURE == zend_hash_find(Z_OBJPROP_P(obj), "stream", sizeof("stream"), (void**)&zstream)) {
 		/* Give the userfilter class a hook back to the stream */
 		ALLOC_INIT_ZVAL(zstream);