core: make sure to destroy all name watching bus slots when we are kicked off the bus (#5294)

Fixes: #4528

2 files changed, 13 insertions, 1 deletions

diff --git a/src/core/dbus.c b/src/core/dbus.c
index a3f701c064..0493e5786c 100644
--- a/src/core/dbus.c
+++ b/src/core/dbus.c
@@ -1041,6 +1041,7 @@ int bus_init(Manager *m, bool try_bus_connect) {
 
 static void destroy_bus(Manager *m, sd_bus **bus) {
         Iterator i;
+        Unit *u;
         Job *j;
 
         assert(m);
@@ -1049,6 +1050,17 @@ static void destroy_bus(Manager *m, sd_bus **bus) {
         if (!*bus)
                 return;
 
+        /* Make sure all bus slots watching names are released. */
+        HASHMAP_FOREACH(u, m->watch_bus, i) {
+                if (!u->match_bus_slot)
+                        continue;
+
+                if (sd_bus_slot_get_bus(u->match_bus_slot) != *bus)
+                        continue;
+
+                u->match_bus_slot = sd_bus_slot_unref(u->match_bus_slot);
+        }
+
         /* Get rid of tracked clients on this bus */
         if (m->subscribed && sd_bus_track_get_bus(m->subscribed) == *bus)
                 m->subscribed = sd_bus_track_unref(m->subscribed);
diff --git a/src/core/unit.c b/src/core/unit.c
index 90d7eea956..5e4b1567d8 100644
--- a/src/core/unit.c
+++ b/src/core/unit.c
@@ -2650,7 +2650,7 @@ void unit_unwatch_bus_name(Unit *u, const char *name) {
         assert(u);
         assert(name);
 
-        hashmap_remove_value(u->manager->watch_bus, name, u);
+        (void) hashmap_remove_value(u->manager->watch_bus, name, u);
         u->match_bus_slot = sd_bus_slot_unref(u->match_bus_slot);
 }