From 094f80738a57a99a9f541f55bbf8aa796235756c Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Wed, 23 Nov 2022 22:03:26 -0700
Subject: [PATCH] [buffer] Handle null buffer in set_message_func

---
 src/hb-buffer.cc | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/src/hb-buffer.cc b/src/hb-buffer.cc
index 9e67e680c..e827e9eb9 100644
--- a/src/hb-buffer.cc
+++ b/src/hb-buffer.cc
@@ -2150,6 +2150,13 @@ hb_buffer_set_message_func (hb_buffer_t *buffer,
 			    hb_buffer_message_func_t func,
 			    void *user_data, hb_destroy_func_t destroy)
 {
+  if (unlikely (hb_object_is_immutable (buffer)))
+  {
+    if (destroy)
+      destroy (user_data);
+    return;
+  }
+
   if (buffer->message_destroy)
     buffer->message_destroy (buffer->message_data);