Skip to content

asm
asm
Closed
Opened by Jussi Judin@barro
Report abuse New issue

ClassReader constructor goes into infinite loop on zero length input streams

Following code leads into an infinite loop with ClassReader constructor when args[0] is an empty file:

public class Asm61InfiniteLoop
{
    public static void main(String[] args) throws java.io.IOException
    {
        java.io.FileInputStream input = new java.io.FileInputStream(args[0]);
        new org.objectweb.asm.ClassReader(input);
    }
}

It looks like the following snippet in the constructor is the culprit where data leads into a zero length array with zero length files and the bytes read from the actual stream never get to -1:

      byte[] data = new byte[inputStream.available()];
      int bytesRead;
      while ((bytesRead = inputStream.read(data, 0, data.length)) != -1) {
        outputStream.write(data, 0, bytesRead);
      }

I would expect this to throw an exception about invalid class data or similar. Other constructors relying on byte[] data being at least 6 elements long lead into out of bounds exception. That is a little bit better, but still weird from user's perspective.