Description: Fix integer overflow in TigerVNC that allowed remote VNC servers to cause a denial of service (crash).
Author: Tim Waugh
Abstract:
 Fix integer overflow in TigerVNC that allowed remote VNC servers to
 cause a denial of service (crash) and possibly execute arbitrary code
 via vectors related to screen size handling, which triggered a heap-based
 buffer overflow, a similar issue to CVE-2014-6051.
 .
 This issue is CVE-2014-8240.

Index: pkg-tigervnc/unix/x0vncserver/Image.cxx
===================================================================
--- pkg-tigervnc.orig/unix/x0vncserver/Image.cxx
+++ pkg-tigervnc/unix/x0vncserver/Image.cxx
@@ -82,6 +82,14 @@ void Image::Init(int width, int height)
   xim = XCreateImage(dpy, vis, DefaultDepth(dpy, DefaultScreen(dpy)),
                      ZPixmap, 0, 0, width, height, BitmapPad(dpy), 0);
 
+  if (xim->bytes_per_line <= 0 ||
+      xim->height <= 0 ||
+      xim->height >= INT_MAX / xim->bytes_per_line) {
+    vlog.error("Invalid display size");
+    XDestroyImage(xim);
+    exit(1);
+  }
+
   xim->data = (char *)malloc(xim->bytes_per_line * xim->height);
   if (xim->data == NULL) {
     vlog.error("malloc() failed");
@@ -257,6 +265,17 @@ void ShmImage::Init(int width, int heigh
     delete shminfo;
     shminfo = NULL;
     return;
+  }
+
+  if (xim->bytes_per_line <= 0 ||
+      xim->height <= 0 ||
+      xim->height >= INT_MAX / xim->bytes_per_line) {
+    vlog.error("Invalid display size");
+    XDestroyImage(xim);
+    xim = NULL;
+    delete shminfo;
+    shminfo = NULL;
+    return;
   }
 
   shminfo->shmid = shmget(IPC_PRIVATE,
Index: pkg-tigervnc/vncviewer/PlatformPixelBuffer.cxx
===================================================================
--- pkg-tigervnc.orig/vncviewer/PlatformPixelBuffer.cxx
+++ pkg-tigervnc/vncviewer/PlatformPixelBuffer.cxx
@@ -49,6 +49,15 @@ PlatformPixelBuffer::PlatformPixelBuffer
     if (!xim)
       throw rdr::Exception("XCreateImage");
 
+    if (xim->bytes_per_line <= 0 ||
+       xim->height <= 0 ||
+       xim->height >= INT_MAX / xim->bytes_per_line) {
+      if (xim)
+       XDestroyImage(xim);
+      xim = NULL;
+      throw rdr::Exception("Invalid display size");
+    }
+
     xim->data = (char*)malloc(xim->bytes_per_line * xim->height);
     if (!xim->data)
       throw rdr::Exception("malloc");
@@ -157,6 +166,16 @@ bool PlatformPixelBuffer::setupShm()
   if (!xim)
     goto free_shminfo;
 
+  if (xim->bytes_per_line <= 0 ||
+      xim->height <= 0 ||
+      xim->height >= INT_MAX / xim->bytes_per_line) {
+    XDestroyImage(xim);
+    xim = NULL;
+    delete shminfo;
+    shminfo = NULL;
+    throw rdr::Exception("Invalid display size");
+  }
+
   shminfo->shmid = shmget(IPC_PRIVATE,
                           xim->bytes_per_line * xim->height,
                           IPC_CREAT|0600);