From dc62509b9be9ec46786703910ec7a33cfc3a74e4 Mon Sep 17 00:00:00 2001
From: flobernd <flobernd@users.noreply.github.com>
Date: Wed, 21 Jun 2017 04:04:58 +0200
Subject: [PATCH] Ignore REX-prefix, if it is not the last prefix before the
 opcode

---
 src/Decoder.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/Decoder.c b/src/Decoder.c
index d42ff54..f3b2190 100644
--- a/src/Decoder.c
+++ b/src/Decoder.c
@@ -777,6 +777,10 @@ static ZydisStatus ZydisCollectOptionalPrefixes(ZydisDecoderContext* context,
         }
         if (!done)
         {
+            if ((prefixByte & 0xF0) != 0x40)
+            {
+                info->details.rex.data[0] = 0x00;       
+            }
             context->prefixes[info->details.prefixes.count] = prefixByte;
             info->details.prefixes.data[info->details.prefixes.count++] = prefixByte;
             ZydisInputSkip(context, info);