ofz#3121 check bounds better

Change-Id: Ib1eacda7e4cdf1d0238532f4e38059a9c30556ac
Reviewed-on: https://gerrit.libreoffice.org/41626Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>

filter/source/graphicfilter/icgm/class4.cxx

@@ -186,7 +186,7 @@ void CGM::ImplDoClass4()
                 sal_uInt32 nType = ImplGetUI16();
                 sal_uInt32 nSize = ImplGetUI( 1 );
 
-                if (static_cast<sal_uIntPtr>(mpEndValidSource - (mpSource + mnParaSize)) < nSize)
+                if (static_cast<sal_uIntPtr>(mpEndValidSource - (mpSource + mnParaSize)) <= nSize)
                     throw css::uno::Exception("attempt to read past end of input", nullptr);
 
                 mpSource[mnParaSize + nSize] = 0;
@@ -224,7 +224,7 @@ void CGM::ImplDoClass4()
                 sal_uInt32 nType = ImplGetUI16();
                 sal_uInt32 nSize = ImplGetUI(1);
 
-                if (static_cast<sal_uIntPtr>(mpEndValidSource - (mpSource + mnParaSize)) < nSize)
+                if (static_cast<sal_uIntPtr>(mpEndValidSource - (mpSource + mnParaSize)) <= nSize)
                     throw css::uno::Exception("attempt to read past end of input", nullptr);
 
                 mpSource[ mnParaSize + nSize ] = 0;
@@ -242,7 +242,7 @@ void CGM::ImplDoClass4()
                 (void)ImplGetUI16(); // nType
                 sal_uInt32 nSize = ImplGetUI( 1 );
 
-                if (static_cast<sal_uIntPtr>(mpEndValidSource - (mpSource + mnParaSize)) < nSize)
+                if (static_cast<sal_uIntPtr>(mpEndValidSource - (mpSource + mnParaSize)) <= nSize)
                     throw css::uno::Exception("attempt to read past end of input", nullptr);
 
                 mpSource[ mnParaSize + nSize ] = 0;