Bug#805534: Potential stack overflow in Correlation.cpp

[Mirko Scholz]

Package: qtiplot
Version: 0.9.8.9-10

On systems that limit the stack space per user, the current implementation of
correlation causes a stack overflow for large tables, say 1e6 rows.  Otherwise
this amount of rows is handled well by Qtiplot.

The attached patch solves the problem, albeit you may want to implement
it differently.

Upstream (www.qtiplot.com) does not accept patches anymore

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--- qtiplot-0.9.8.9/qtiplot/src/analysis/Correlation.cpp     	2015-11-04 11:36:44.139928471 +0100
+++ qtiplot-0.9.8.9/qtiplot/src/analysis/Correlation.cpp	2015-11-04 11:44:03.501165132 +0100
@@ -150,21 +150,22 @@
 
     if (d_n > d_table->numRows())
         d_table->setNumRows(d_n);
 
 	int cols = d_table->numCols();
 	int cols2 = cols+1;
 	d_table->addCol();
 	d_table->addCol();
 	int n = d_n/2;
 
-    double x_temp[d_n], y_temp[d_n];
+	double *x_temp = new double[d_n];
+	double *y_temp = new double[d_n];
 	for (int i = 0; i<d_n; i++){
 	    double x = i - n;
         x_temp[i] = x;
 
         double y;
         if(i < n)
 			y = d_x[n + i];
 		else
 			y = d_x[i - n];
         y_temp[i] = y;
@@ -185,11 +186,13 @@
 	if (d_graphics_display){
 		if (!d_output_graph)
 			createOutputGraph();
 
     	DataCurve *c = new DataCurve(d_table, d_table->colName(cols), d_table->colName(cols2));
 		c->setData(x_temp, y_temp, d_n);
 		c->setPen(QPen(d_curveColor, 1));
 		d_output_graph->insertPlotItem(c, Graph::Line);
 		d_output_graph->updatePlot();
 	}
+	delete[] x_temp;
+	delete[] y_temp;
 }
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