Discard null-containing strings before updating the user directory (#12762)

2 files changed, 5 insertions, 8 deletions

diff --git a/synapse/storage/databases/main/events.py b/synapse/storage/databases/main/events.py
index 42d484dc98..0df8ff5395 100644
--- a/synapse/storage/databases/main/events.py
+++ b/synapse/storage/databases/main/events.py
@@ -52,6 +52,7 @@ from synapse.storage.util.sequence import SequenceGenerator
 from synapse.types import JsonDict, StateMap, get_domain_from_id
 from synapse.util import json_encoder
 from synapse.util.iterutils import batch_iter, sorted_topologically
+from synapse.util.stringutils import non_null_str_or_none
 
 if TYPE_CHECKING:
     from synapse.server import HomeServer
@@ -1728,9 +1729,6 @@ class PersistEventsStore:
                 not affect the current local state.
         """
 
-        def non_null_str_or_none(val: Any) -> Optional[str]:
-            return val if isinstance(val, str) and "\u0000" not in val else None
-
         self.db_pool.simple_insert_many_txn(
             txn,
             table="room_memberships",
diff --git a/synapse/storage/databases/main/user_directory.py b/synapse/storage/databases/main/user_directory.py
index df772d4721..028db69af3 100644
--- a/synapse/storage/databases/main/user_directory.py
+++ b/synapse/storage/databases/main/user_directory.py
@@ -29,6 +29,7 @@ from typing import (
 from typing_extensions import TypedDict
 
 from synapse.api.errors import StoreError
+from synapse.util.stringutils import non_null_str_or_none
 
 if TYPE_CHECKING:
     from synapse.server import HomeServer
@@ -469,11 +470,9 @@ class UserDirectoryBackgroundUpdateStore(StateDeltasStore):
         """
         Update or add a user's profile in the user directory.
         """
-        # If the display name or avatar URL are unexpected types, overwrite them.
-        if not isinstance(display_name, str):
-            display_name = None
-        if not isinstance(avatar_url, str):
-            avatar_url = None
+        # If the display name or avatar URL are unexpected types, replace with None.
+        display_name = non_null_str_or_none(display_name)
+        avatar_url = non_null_str_or_none(avatar_url)
 
         def _update_profile_in_user_dir_txn(txn: LoggingTransaction) -> None:
             self.db_pool.simple_upsert_txn(