[raster] Fix unintentional int overflow

Author: nyalldawson

src/core/raster/qgsrasterblock.cpp

@@ -679,7 +679,7 @@ bool QgsRasterBlock::convert( QGis::DataType destDataType )
 
   if ( typeIsNumeric( mDataType ) && typeIsNumeric( destDataType ) )
   {
-    void *data = convert( mData, mDataType, destDataType, mWidth * mHeight );
+    void *data = convert( mData, mDataType, destDataType, ( qgssize )mWidth * ( qgssize )mHeight );
 
     if ( data == 0 )
     {
@@ -728,7 +728,7 @@ void QgsRasterBlock::applyNoDataValues( const QgsRasterRangeList & rangeList )
     return;
   }
 
-  qgssize size = mWidth * mHeight;
+  qgssize size = ( qgssize )mWidth * ( qgssize )mHeight;
   for ( qgssize i = 0; i < size; ++i )
   {
     double val = value( i );

src/core/raster/qgsrasterdataprovider.cpp

@@ -182,8 +182,8 @@ QgsRasterBlock * QgsRasterDataProvider::block( int theBandNo, QgsRectangle  cons
           return block;
         }
 
-        qgssize tmpIndex = tmpRow * tmpWidth + tmpCol;
-        qgssize index = row * theWidth + col;
+        qgssize tmpIndex = ( qgssize )tmpRow * ( qgssize )tmpWidth + tmpCol;
+        qgssize index = row * ( qgssize )theWidth + col;
 
         char *tmpBits = tmpBlock->bits( tmpIndex );
         char *bits = block->bits( index );