Make sure a retention policy is a state event (#8527)

* Make sure a retention policy is a state event

* Changelog

1 files changed, 4 insertions, 0 deletions

diff --git a/synapse/storage/databases/main/events.py b/synapse/storage/databases/main/events.py

index 18def01f50..f766e148a0 100644
--- a/synapse/storage/databases/main/events.py
+++ b/synapse/storage/databases/main/events.py
@@ -1241,6 +1241,10 @@ class PersistEventsStore:
             )
 
     def _store_retention_policy_for_room_txn(self, txn, event):
+        if not event.is_state():
+            logger.debug("Ignoring non-state m.room.retention event")
+            return
+
         if hasattr(event, "content") and (
             "min_lifetime" in event.content or "max_lifetime" in event.content
         ):