From 77d439dddf70e5c65949f2099c19fb13f156430f Mon Sep 17 00:00:00 2001
From: Kegan Dougal <kegan@matrix.org>
Date: Mon, 19 Jul 2021 10:21:25 +0100
Subject: [PATCH] Check for missing state keys to avoid panicking

---
 federationapi/routing/leave.go | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/federationapi/routing/leave.go b/federationapi/routing/leave.go
index a5231004c..e31a32402 100644
--- a/federationapi/routing/leave.go
+++ b/federationapi/routing/leave.go
@@ -174,6 +174,13 @@ func SendLeave(
 		}
 	}
 
+	if event.StateKey() == nil {
+		return util.JSONResponse{
+			Code: http.StatusBadRequest,
+			JSON: jsonerror.InvalidArgumentValue("missing state_key"),
+		}
+	}
+
 	// Check if the user has already left. If so, no-op!
 	queryReq := &api.QueryLatestEventsAndStateRequest{
 		RoomID: roomID,