From 558f922788ccceaa80c31bf0e379be4c96598d13 Mon Sep 17 00:00:00 2001
From: Ebrahim Byagowi <ebrahim@gnu.org>
Date: Tue, 3 Mar 2020 20:27:19 +0330
Subject: [PATCH] [fuzz] Avoid empty memcpy and ubsan complain by length
 checking before memcpy

---
 test/fuzzing/hb-shape-fuzzer.cc | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/test/fuzzing/hb-shape-fuzzer.cc b/test/fuzzing/hb-shape-fuzzer.cc
index c761b2a39..eb03132c3 100644
--- a/test/fuzzing/hb-shape-fuzzer.cc
+++ b/test/fuzzing/hb-shape-fuzzer.cc
@@ -41,7 +41,8 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size)
   unsigned int len = sizeof (text32);
   if (size < len)
     len = size;
-  memcpy(text32, data + size - len, len);
+  if (len)
+    memcpy(text32, data + size - len, len);
 
   hb_buffer_t *buffer = hb_buffer_create ();
   hb_buffer_add_utf32 (buffer, text32, sizeof (text32) / sizeof (text32[0]), 0, -1);