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From bugzi...@apache.org
Subject DO NOT REPLY [Bug 16705] New: - Pending requests can corrupt data of recycled sessions
Date Mon, 03 Feb 2003 14:33:41 GMT
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http://nagoya.apache.org/bugzilla/show_bug.cgi?id=16705

Pending requests can corrupt data of recycled sessions

           Summary: Pending requests can corrupt data of recycled sessions
           Product: Tomcat 4
           Version: 4.1.12
          Platform: Sun
        OS/Version: Solaris
            Status: NEW
          Severity: Critical
          Priority: Other
         Component: Catalina
        AssignedTo: tomcat-dev@jakarta.apache.org
        ReportedBy: thomas.siedschlag@gmx.net


Sometimes we have problems that one user can see the stored session data of
another one.
We find out that the recycling of invalidated sessions is unsafe, if there are
pending requests. The pending request can write some data in a recycled session,
if the associated session of this request were invalidated during the request!

Consider the following example.

-- first.jsp
<%
  // invalidate a valid session if there is one
  if(request.getSession(false) != null) {
    request.getSession().invalidate();
  }

  // get a new session
  request.getSession(true);

  // print out the new session id
  out.write(request.getSession().getId()+"<br>");

  out.write("<a href=\"second.jsp\">Go</a>");
%>



-- second.jsp
<%
  // do the work only if there is a session
  if(session != null && !session.isNew()) {

    // save the old session id
    String firstId = session.getId();

    // print out the old session id
    out.write(firstId+"<br>");
    out.write("<br>");

    // this wait of 10 seconds is only to achieve reproducibility
    System.out.println("start!");
    try {
      synchronized(this) {
        wait(10000);
      }
    }
    catch(Exception e) {
    }
    System.out.println("end!");

    // save id in session if there is no one
    if(session.getAttribute("Id") == null) {
      session.setAttribute("Id",firstId);
    }

    // get the saved id
    String savedId = (String) session.getAttribute("Id");

    // print out the 'actual' session id and the saved session id
    out.write(session.getId()+"<br>");
    out.write(savedId+"<br>");
  }
  else {
    out.write("Please call <a href=\"first.jsp\">this</a> first!");
  }
%>

To reproduce the bug do the following:

1. Call first.jsp - You will get a new session.

2. Call second.jsp.

3. Wait if "start!" is logged on the Tomcat console.

4. Break up the request to second.jsp in your browser.

5. Call first.jsp again - The old session will invalidate and you will get a new
  session again.

6. Call second.jsp again.

7. In the response the last two printed ids differs!

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