fix $links substitution for devices without any link

Reported-by: Michel Hermier <michel.hermier@gmail.com>

diff --git a/udev/udev-event.c b/udev/udev-event.c
index 27bb5eb79ac545e6f60fdc29bf2f83752f3e436e..32b45e9baca6c039932b4b875b4b03b15425d9a7 100644 (file)
--- a/udev/udev-event.c
+++ b/udev/udev-event.c
@@ -231,8 +231,9 @@ found:
                        break;
                case SUBST_DRIVER:
                        if (event->dev_parent != NULL) {
-                               const char *driver = udev_device_get_driver(event->dev_parent);
+                               const char *driver;
 
+                               driver = udev_device_get_driver(event->dev_parent);
                                if (driver == NULL)
                                        break;
                                util_strlcat(string, driver, maxsize);
@@ -398,6 +399,8 @@ found:
                                struct udev_list_entry *list_entry;
 
                                list_entry = udev_device_get_devlinks_list_entry(dev);
+                               if (list_entry == NULL)
+                                       break;
                                util_strlcat(string, &udev_list_entry_get_name(list_entry)[devlen], maxsize);
                                udev_list_entry_foreach(list_entry, udev_list_entry_get_next(list_entry)) {
                                        util_strlcat(string, " ", maxsize);
@@ -426,6 +429,8 @@ found:
                                if (list_entry == NULL)
                                        break;
                                value = udev_list_entry_get_value(list_entry);
+                               if (value == NULL)
+                                       break;
                                dbg(event->udev, "substitute env '%s=%s'\n", attr, value);
                                util_strlcat(string, value, maxsize);
                                break;