Be stricter about JSON that is accepted by Synapse (#8106)

2 files changed, 9 insertions, 7 deletions

diff --git a/synapse/rest/client/v1/room.py b/synapse/rest/client/v1/room.py
index 2ab30ce897..f216382636 100644
--- a/synapse/rest/client/v1/room.py
+++ b/synapse/rest/client/v1/room.py
@@ -21,8 +21,6 @@ import re
 from typing import List, Optional
 from urllib import parse as urlparse
 
-from canonicaljson import json
-
 from synapse.api.constants import EventTypes, Membership
 from synapse.api.errors import (
     AuthError,
@@ -46,6 +44,7 @@ from synapse.rest.client.v2_alpha._base import client_patterns
 from synapse.storage.state import StateFilter
 from synapse.streams.config import PaginationConfig
 from synapse.types import RoomAlias, RoomID, StreamToken, ThirdPartyInstanceID, UserID
+from synapse.util import json_decoder
 
 MYPY = False
 if MYPY:
@@ -519,7 +518,9 @@ class RoomMessageListRestServlet(RestServlet):
         filter_str = parse_string(request, b"filter", encoding="utf-8")
         if filter_str:
             filter_json = urlparse.unquote(filter_str)
-            event_filter = Filter(json.loads(filter_json))  # type: Optional[Filter]
+            event_filter = Filter(
+                json_decoder.decode(filter_json)
+            )  # type: Optional[Filter]
             if (
                 event_filter
                 and event_filter.filter_json.get("event_format", "client")
@@ -631,7 +632,9 @@ class RoomEventContextServlet(RestServlet):
         filter_str = parse_string(request, b"filter", encoding="utf-8")
         if filter_str:
             filter_json = urlparse.unquote(filter_str)
-            event_filter = Filter(json.loads(filter_json))  # type: Optional[Filter]
+            event_filter = Filter(
+                json_decoder.decode(filter_json)
+            )  # type: Optional[Filter]
         else:
             event_filter = None
 
diff --git a/synapse/rest/client/v2_alpha/sync.py b/synapse/rest/client/v2_alpha/sync.py
index a5c24fbd63..96488b131a 100644
--- a/synapse/rest/client/v2_alpha/sync.py
+++ b/synapse/rest/client/v2_alpha/sync.py
@@ -16,8 +16,6 @@
 import itertools
 import logging
 
-from canonicaljson import json
-
 from synapse.api.constants import PresenceState
 from synapse.api.errors import Codes, StoreError, SynapseError
 from synapse.api.filtering import DEFAULT_FILTER_COLLECTION, FilterCollection
@@ -29,6 +27,7 @@ from synapse.handlers.presence import format_user_presence_state
 from synapse.handlers.sync import SyncConfig
 from synapse.http.servlet import RestServlet, parse_boolean, parse_integer, parse_string
 from synapse.types import StreamToken
+from synapse.util import json_decoder
 
 from ._base import client_patterns, set_timeline_upper_limit
 
@@ -125,7 +124,7 @@ class SyncRestServlet(RestServlet):
             filter_collection = DEFAULT_FILTER_COLLECTION
         elif filter_id.startswith("{"):
             try:
-                filter_object = json.loads(filter_id)
+                filter_object = json_decoder.decode(filter_id)
                 set_timeline_upper_limit(
                     filter_object, self.hs.config.filter_timeline_limit
                 )