From 60e8a2f61d51126e111823c7b177fbb829035eb9 Mon Sep 17 00:00:00 2001
From: Pale Moon <git-repo@palemoon.org>
Date: Sat, 22 Apr 2017 11:49:58 +0200
Subject: [PATCH] Fix another old/ancient issue in stream converters.

---
 netwerk/streamconv/converters/nsBinHexDecoder.cpp | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/netwerk/streamconv/converters/nsBinHexDecoder.cpp b/netwerk/streamconv/converters/nsBinHexDecoder.cpp
index 9c78cebe4a..509f97e04c 100644
--- a/netwerk/streamconv/converters/nsBinHexDecoder.cpp
+++ b/netwerk/streamconv/converters/nsBinHexDecoder.cpp
@@ -170,7 +170,9 @@ nsresult nsBinHexDecoder::ProcessNextState(nsIRequest * aRequest, nsISupports *
       break;
 
     case BINHEX_STATE_FNAME:
-      mName.BeginWriting()[mCount] = c;
+      if (mCount < mName.Length()) {
+        mName.BeginWriting()[mCount] = c;
+      }
 
       if (++mCount > mName.Length())
       {