From 8f4573bde656fa76d5b4423edd1804809db19f78 Mon Sep 17 00:00:00 2001
From: Markus Sattler <help.markus+git@gmail.com>
Date: Fri, 9 Oct 2015 14:32:19 +0200
Subject: [PATCH] fix possible free of null in String

---
 hardware/esp8266com/esp8266/cores/esp8266/WString.cpp | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/hardware/esp8266com/esp8266/cores/esp8266/WString.cpp b/hardware/esp8266com/esp8266/cores/esp8266/WString.cpp
index 511f916c8f..f92344b84e 100644
--- a/hardware/esp8266com/esp8266/cores/esp8266/WString.cpp
+++ b/hardware/esp8266com/esp8266/cores/esp8266/WString.cpp
@@ -118,7 +118,9 @@ ICACHE_FLASH_ATTR String::String(double value, unsigned char decimalPlaces) {
 }
 
 ICACHE_FLASH_ATTR String::~String() {
-    free(buffer);
+    if(buffer) {
+        free(buffer);
+    }
 }
 
 // /*********************************************/