From b994e86e359fd095f82feabbf38fb18a5d10e0ae Mon Sep 17 00:00:00 2001
From: Andrew Morgan <1342360+anoadragon453@users.noreply.github.com>
Date: Tue, 31 Mar 2020 14:51:22 +0100
Subject: [PATCH] Only setdefault for signatures if device has key_json (#7177)

---
 changelog.d/7177.bugfix                     |  1 +
 synapse/storage/data_stores/main/devices.py | 24 ++++++++++++---------
 2 files changed, 15 insertions(+), 10 deletions(-)
 create mode 100644 changelog.d/7177.bugfix

diff --git a/changelog.d/7177.bugfix b/changelog.d/7177.bugfix
new file mode 100644
index 000000000..329a96cb0
--- /dev/null
+++ b/changelog.d/7177.bugfix
@@ -0,0 +1 @@
+Fix a bug which could cause outbound federation traffic to stop working if a client uploaded an incorrect e2e device signature.
\ No newline at end of file
diff --git a/synapse/storage/data_stores/main/devices.py b/synapse/storage/data_stores/main/devices.py
index 3140e1b72..20995e1b7 100644
--- a/synapse/storage/data_stores/main/devices.py
+++ b/synapse/storage/data_stores/main/devices.py
@@ -286,14 +286,16 @@ class DeviceWorkerStore(SQLBaseStore):
                     key_json = device.get("key_json", None)
                     if key_json:
                         result["keys"] = db_to_json(key_json)
+
+                        if "signatures" in device:
+                            for sig_user_id, sigs in device["signatures"].items():
+                                result["keys"].setdefault("signatures", {}).setdefault(
+                                    sig_user_id, {}
+                                ).update(sigs)
+
                     device_display_name = device.get("device_display_name", None)
                     if device_display_name:
                         result["device_display_name"] = device_display_name
-                    if "signatures" in device:
-                        for sig_user_id, sigs in device["signatures"].items():
-                            result["keys"].setdefault("signatures", {}).setdefault(
-                                sig_user_id, {}
-                            ).update(sigs)
                 else:
                     result["deleted"] = True
 
@@ -494,14 +496,16 @@ class DeviceWorkerStore(SQLBaseStore):
                 key_json = device.get("key_json", None)
                 if key_json:
                     result["keys"] = db_to_json(key_json)
+
+                    if "signatures" in device:
+                        for sig_user_id, sigs in device["signatures"].items():
+                            result["keys"].setdefault("signatures", {}).setdefault(
+                                sig_user_id, {}
+                            ).update(sigs)
+
                 device_display_name = device.get("device_display_name", None)
                 if device_display_name:
                     result["device_display_name"] = device_display_name
-                if "signatures" in device:
-                    for sig_user_id, sigs in device["signatures"].items():
-                        result["keys"].setdefault("signatures", {}).setdefault(
-                            sig_user_id, {}
-                        ).update(sigs)
 
                 results.append(result)