mount: check for NULL before reading pm->what

Since a57f7e2c828b85, a mount unit with garbage in it would cause
systemd to crash on loading it.

ref: https://bugs.freedesktop.org/show_bug.cgi?id=70148

diff --git a/src/core/mount.c b/src/core/mount.c
index 93bfa99f3fe123525b6c290fb9985a1100ef3681..db055f0a00ce204d156296e192460ef1dbc9219f 100644 (file)
--- a/src/core/mount.c
+++ b/src/core/mount.c
@@ -182,7 +182,7 @@ static int mount_add_mount_links(Mount *m) {
          * for the source path (if this is a bind mount) to be
          * available. */
         pm = get_mount_parameters_fragment(m);
-        if (pm && path_is_absolute(pm->what)) {
+        if (pm && pm->what && path_is_absolute(pm->what)) {
                 r = unit_require_mounts_for(UNIT(m), pm->what);
                 if (r < 0)
                         return r;