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[Qemu-devel] [Bug 1668273] Re: DoS possible on - a QEMU process using us
From: |
Nehal J Wani |
Subject: |
[Qemu-devel] [Bug 1668273] Re: DoS possible on - a QEMU process using userspace SLIRP? |
Date: |
Mon, 27 Feb 2017 14:23:36 -0000 |
** Summary changed:
- DDoS possible on - a QEMU process using userspace SLIRP?
+ DoS possible on - a QEMU process using userspace SLIRP?
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https://bugs.launchpad.net/bugs/1668273
Title:
DoS possible on - a QEMU process using userspace SLIRP?
Status in QEMU:
New
Bug description:
Steps to reproduce:
- Launch a VM using QEMU (2.8.0):
$ qemu-system-x86_64 \
-machine accel=kvm \
-hda Fedora-Cloud-Base-25-1.3.x86_64.qcow2 \
-m 2G \
-smp 2 \
-vnc :8 \
-boot dc \
-vga std \
-cpu host \
-net nic,vlan=0 \
-net user,vlan=0,hostfwd=tcp::10024-:22,hostfwd=tcp::8082-:80
- SSH into the VM, install httpd, start httpd
$ ssh -p 10024 address@hidden 'dnf install -y httpd && systemctl start
httpd'
- Compile and run the following Java program (on the host):
$ cat <<EOF > URLConnectionReader.java
import java.net.*;
import java.io.*;
public class URLConnectionReader {
public static void main(String[] args) throws Exception {
int i = 0;
while (i < 1024) {
URL this_is_404 = new URL("http://localhost:8082/blah");
URLConnection yc = this_is_404.openConnection();
try {
BufferedReader in = new BufferedReader(new InputStreamReader(
yc.getInputStream()));
String inputLine;
while ((inputLine = in.readLine()) != null)
System.out.println(inputLine);
in.close();
} catch (Exception e) {
//HttpURLConnection urlConnection = (HttpURLConnection) yc;
//urlConnection.disconnect();
}
i++;
}
Thread.sleep(1000000000);
}
}
$ javac URLConnectionReader.java
$ java URLConnectionReader &
The java program tries to open a lot of HTTP connections, but never
calls disconnect() on any.
- Take a look at the list of open FDs of the qemu process:
$ ls -tl /proc/${qemu-pid}/fd
$ lsof -p ${qemu-pid}
All of the TCP connections will be stuck at FIN_WAIT2
The VM becomes unresponsive. Neither SSH or VNC works after this.
To manage notifications about this bug go to:
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- [Qemu-devel] [Bug 1668273] [NEW] DDoS possible on - a QEMU process using userspace SLIRP?, Nehal J Wani, 2017/02/27
- [Qemu-devel] [Bug 1668273] Re: DoS possible on - a QEMU process using userspace SLIRP?,
Nehal J Wani <=
- [Qemu-devel] [Bug 1668273] Re: DoS possible on - a QEMU process using userspace SLIRP?, Nehal J Wani, 2017/02/27
- [Qemu-devel] [Bug 1668273] Re: DoS possible on - a QEMU process using userspace SLIRP?, Daniel Berrange, 2017/02/27
- [Qemu-devel] [Bug 1668273] Re: DoS possible on - a QEMU process using userspace SLIRP?, Nehal J Wani, 2017/02/27
- [Qemu-devel] [Bug 1668273] Re: DoS possible on - a QEMU process using userspace SLIRP?, Daniel Berrange, 2017/02/27
- [Qemu-devel] [Bug 1668273] Re: DoS possible on - a QEMU process using userspace SLIRP?, Greg Kurz, 2017/02/27