(Fkill_buffer): gcpro BUF during kill_buffer_processes

and check that buffer is still alive upon return.

src/buffer.c

@@ -1458,7 +1458,16 @@ with SIGHUP.  */)
   unlock_buffer (b);
 #endif /* CLASH_DETECTION */
 
+  GCPRO1 (buf);
   kill_buffer_processes (buf);
+  UNGCPRO;
+
+  /* Killing buffer processes may run sentinels which may
+     have called kill-buffer.  */
+
+  if (NILP (b->name))
+    return Qnil;
+
   clear_charpos_cache (b);
 
   tem = Vinhibit_quit;