core/exec: do not crash with UtmpMode=user without User= setting

Fixes https://bugzilla.redhat.com/show_bug.cgi?id=2264404.

Replaces #31356.

diff --git a/src/core/exec-invoke.c b/src/core/exec-invoke.c
index c62b7385cb3b09dde4d52ce9c2905118a12ffb1e..c012a359a0bb9a30983c5a012fad183ce810451f 100644 (file)
--- a/src/core/exec-invoke.c
+++ b/src/core/exec-invoke.c
@@ -4451,6 +4451,16 @@ int exec_invoke(
 
 #if ENABLE_UTMP
         if (context->utmp_id) {
+                _cleanup_free_ char *username_alloc = NULL;
+
+                if (!username && context->utmp_mode == EXEC_UTMP_USER) {
+                        username_alloc = uid_to_name(uid_is_valid(uid) ? uid : saved_uid);
+                        if (!username_alloc) {
+                                *exit_status = EXIT_USER;
+                                return log_oom();
+                        }
+                }
+
                 const char *line = context->tty_path ?
                         (path_startswith(context->tty_path, "/dev/") ?: context->tty_path) :
                         NULL;
@@ -4459,7 +4469,7 @@ int exec_invoke(
                                       context->utmp_mode == EXEC_UTMP_INIT  ? INIT_PROCESS :
                                       context->utmp_mode == EXEC_UTMP_LOGIN ? LOGIN_PROCESS :
                                       USER_PROCESS,
-                                      username);
+                                      username ?: username_alloc);
         }
 #endif
 

diff --git a/src/shared/utmp-wtmp.c b/src/shared/utmp-wtmp.c
index 6c3238a9c6a8b20d347d1c978dab0f41f48295db..267b350276c723efcdfc0f46fd3b0baf3dea6cb9 100644 (file)
--- a/src/shared/utmp-wtmp.c
+++ b/src/shared/utmp-wtmp.c
@@ -179,6 +179,7 @@ int utmp_put_init_process(const char *id, pid_t pid, pid_t sid, const char *line
         int r;
 
         assert(id);
+        assert(ut_type != USER_PROCESS || user);
 
         init_timestamp(&store, 0);