From 6fe5ea40aa8c7fd02ffc640d961d8d8f2afc5f37 Mon Sep 17 00:00:00 2001
From: Alex Hultman <alexhultman@gmail.com>
Date: Wed, 1 Jan 2020 17:41:43 +0100
Subject: [PATCH] Silence an UBSAN fuzzing fault

---
 src/WebSocketProtocol.h | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/WebSocketProtocol.h b/src/WebSocketProtocol.h
index 616ca94..cb9106a 100644
--- a/src/WebSocketProtocol.h
+++ b/src/WebSocketProtocol.h
@@ -167,7 +167,10 @@ static inline size_t formatClosePayload(char *dst, uint16_t code, const char *me
     if (code) {
         code = cond_byte_swap<uint16_t>(code);
         memcpy(dst, &code, 2);
-        memcpy(dst + 2, message, length);
+        /* It is invalid to pass nullptr to memcpy, even though length is 0 */
+        if (message) {
+            memcpy(dst + 2, message, length);
+        }
         return length + 2;
     }
     return 0;