Zhenliang Su created SSHD-921:
---------------------------------
Summary: OutOfMemory Error in extreme situations
Key: SSHD-921
URL: https://issues.apache.org/jira/browse/SSHD-921
Project: MINA SSHD
Issue Type: Bug
Affects Versions: 1.7.0, 2.3.0
Reporter: Zhenliang Su
Attachments: Main.java, jstack.txt
The demo code run in my local machine.
When I 'ssh [email protected] -p 2233', my demo will use the agent forwarding
feature to login 10.10.16.201.
In most cases, it's ok. But in few cases, for example, client disconnect
suddenly, it will lead to OutOfMemory Error.
To simulate this scenario of OutOfMemory Error, I did some trick to the sshd
code:
1. In org.apache.sshd.common.future.DefaultSshFuture#setValue:
{code:java}
public void setValue(Object newValue) {
// to simulate race condition
try {
Thread.sleep(10);
} catch (Exception e) {
// ignore
}
synchronized (lock) {
// Allow only once.
if (result != null) {
return;
}
result = (newValue != null) ? newValue : GenericUtils.NULL;
lock.notifyAll();
}
notifyListeners();
}
{code}
2. In org.apache.sshd.agent.local.AgentForwardedChannel#doWriteData:
{code:java}
protected void doWriteData(byte[] data, int off, long len) throws IOException {
ValidateUtils.checkTrue(len <= Integer.MAX_VALUE, "Data length exceeds
int boundaries: %d", len);
Buffer message = null;
synchronized (receiveBuffer) {
receiveBuffer.putBuffer(new ByteArrayBuffer(data, off, (int) len));
// to simulate client disconnect suddenly
if (false && receiveBuffer.available() >= 4) {
off = receiveBuffer.rpos();
len = receiveBuffer.getInt();
receiveBuffer.rpos(off);
if (receiveBuffer.available() >= (4 + len)) {
message = new ByteArrayBuffer(receiveBuffer.getBytes());
receiveBuffer.compact();
}
}
}
if (message != null) {
synchronized (messages) {
messages.offer(message);
messages.notifyAll();
}
}
}
{code}
After two munites, my console displayed
'[sshd-SshClient[720b3c53]-timer-thread-1] INFO
org.apache.sshd.client.session.ClientSessionImpl -
Disconnecting(ClientSessionImpl[root@/10.10.16.201:8022]):
SSH2_DISCONNECT_PROTOCOL_ERROR - Session has timed out waiting for
authentication after 120000 ms.' every second, and finally lead to OutOfMemory
Error.
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