Handle string read receipt data (#10606)

* Handle string read receipt data

Signed-off-by: Šimon Brandner <simon.bra.ag@gmail.com>

* Test that we handle string read receipt data

Signed-off-by: Šimon Brandner <simon.bra.ag@gmail.com>

* Add changelog for #10606

Signed-off-by: Šimon Brandner <simon.bra.ag@gmail.com>

* Add docs

Signed-off-by: Šimon Brandner <simon.bra.ag@gmail.com>

* Ignore malformed RRs

Signed-off-by: Šimon Brandner <simon.bra.ag@gmail.com>

* Only surround hidden = ...

Signed-off-by: Šimon Brandner <simon.bra.ag@gmail.com>

* Remove unnecessary argument

Signed-off-by: Šimon Brandner <simon.bra.ag@gmail.com>

* Update changelog.d/10606.bugfix

Co-authored-by: Andrew Morgan <1342360+anoadragon453@users.noreply.github.com>

1 files changed, 8 insertions, 1 deletions

diff --git a/synapse/handlers/receipts.py b/synapse/handlers/receipts.py

index 5fd4525700..fb495229a7 100644
--- a/synapse/handlers/receipts.py
+++ b/synapse/handlers/receipts.py
@@ -188,7 +188,14 @@ class ReceiptEventSource:
 
                 new_users = {}
                 for rr_user_id, user_rr in m_read.items():
-                    hidden = user_rr.get("hidden", None)
+                    try:
+                        hidden = user_rr.get("hidden")
+                    except AttributeError:
+                        # Due to https://github.com/matrix-org/synapse/issues/10376
+                        # there are cases where user_rr is a string, in those cases
+                        # we just ignore the read receipt
+                        continue
+
                     if hidden is not True or rr_user_id == user_id:
                         new_users[rr_user_id] = user_rr.copy()
                         # If hidden has a value replace hidden with the correct prefixed key