This patch fixes CVE-2021-3560, "local privilege escalation using
polkit_system_bus_name_get_creds_sync()":

  https://www.openwall.com/lists/oss-security/2021/06/03/1

Patch from <https://gitlab.freedesktop.org/polkit/polkit/-/commit/a04d13a>.

diff --git a/src/polkit/polkitsystembusname.c b/src/polkit/polkitsystembusname.c
index 8daa12cb9093c1d765c7b83654a2b8d0d382378e..8ed13631508dd96624898df90ee2ece4dcf3e1e5 100644
--- a/src/polkit/polkitsystembusname.c
+++ b/src/polkit/polkitsystembusname.c
@@ -435,6 +435,9 @@ polkit_system_bus_name_get_creds_sync (PolkitSystemBusName           *system_bus
   while (!((data.retrieved_uid && data.retrieved_pid) || data.caught_error))
     g_main_context_iteration (tmp_context, TRUE);
 
+  if (data.caught_error)
+    goto out;
+
   if (out_uid)
     *out_uid = data.uid;
   if (out_pid)