From 9f615301aba1cc54a749950bf9462c5a85217bc4 Mon Sep 17 00:00:00 2001
From: Pierre Ossman <ossman@cendio.se>
Date: Tue, 10 Sep 2019 15:25:30 +0200
Subject: [PATCH] Add write protection to OffsetPixelBuffer

No one should every try to write to this buffer. Enforce that by
throwing an exception if any one tries to get a writeable pointer
to the data.
---
 common/rfb/EncodeManager.cxx | 6 ++++++
 common/rfb/EncodeManager.h   | 3 +++
 2 files changed, 9 insertions(+)

diff --git a/common/rfb/EncodeManager.cxx b/common/rfb/EncodeManager.cxx
index 1653cea..66ba432 100644
--- a/common/rfb/EncodeManager.cxx
+++ b/common/rfb/EncodeManager.cxx
@@ -24,6 +24,7 @@
 #include <rfb/SMsgWriter.h>
 #include <rfb/UpdateTracker.h>
 #include <rfb/LogWriter.h>
+#include <rfb/Exception.h>
 
 #include <rfb/RawEncoder.h>
 #include <rfb/RREEncoder.h>
@@ -895,6 +896,11 @@ void EncodeManager::OffsetPixelBuffer::update(const PixelFormat& pf,
   setBuffer(width, height, (rdr::U8*)data_, stride_);
 }
 
+rdr::U8* EncodeManager::OffsetPixelBuffer::getBufferRW(const Rect& r, int* stride)
+{
+  throw rfb::Exception("Invalid write attempt to OffsetPixelBuffer");
+}
+
 // Preprocessor generated, optimised methods
 
 #define BPP 8
diff --git a/common/rfb/EncodeManager.h b/common/rfb/EncodeManager.h
index 79db950..7d47420 100644
--- a/common/rfb/EncodeManager.h
+++ b/common/rfb/EncodeManager.h
@@ -124,6 +124,9 @@ namespace rfb {
 
       void update(const PixelFormat& pf, int width, int height,
                   const rdr::U8* data_, int stride);
+
+    private:
+      virtual rdr::U8* getBufferRW(const Rect& r, int* stride);
     };
 
     OffsetPixelBuffer offsetPixelBuffer;