Do not refuse to set read_marker if previous event_id is in wrong room (#16990)

2 files changed, 7 insertions, 5 deletions

diff --git a/synapse/handlers/read_marker.py b/synapse/handlers/read_marker.py
index 135a662267..fb39c8e04b 100644
--- a/synapse/handlers/read_marker.py
+++ b/synapse/handlers/read_marker.py
@@ -55,12 +55,12 @@ class ReadMarkerHandler:
 
             should_update = True
             # Get event ordering, this also ensures we know about the event
-            event_ordering = await self.store.get_event_ordering(event_id)
+            event_ordering = await self.store.get_event_ordering(event_id, room_id)
 
             if existing_read_marker:
                 try:
                     old_event_ordering = await self.store.get_event_ordering(
-                        existing_read_marker["event_id"]
+                        existing_read_marker["event_id"], room_id
                     )
                 except SynapseError:
                     # Old event no longer exists, assume new is ahead. This may
diff --git a/synapse/storage/databases/main/events_worker.py b/synapse/storage/databases/main/events_worker.py
index 81fccfbccb..e39d4b9624 100644
--- a/synapse/storage/databases/main/events_worker.py
+++ b/synapse/storage/databases/main/events_worker.py
@@ -1995,16 +1995,18 @@ class EventsWorkerStore(SQLBaseStore):
         return rows, to_token, True
 
     @cached(max_entries=5000)
-    async def get_event_ordering(self, event_id: str) -> Tuple[int, int]:
+    async def get_event_ordering(self, event_id: str, room_id: str) -> Tuple[int, int]:
         res = await self.db_pool.simple_select_one(
             table="events",
             retcols=["topological_ordering", "stream_ordering"],
-            keyvalues={"event_id": event_id},
+            keyvalues={"event_id": event_id, "room_id": room_id},
             allow_none=True,
         )
 
         if not res:
-            raise SynapseError(404, "Could not find event %s" % (event_id,))
+            raise SynapseError(
+                404, "Could not find event %s in room %s" % (event_id, room_id)
+            )
 
         return int(res[0]), int(res[1])