[jira] [Comment Edited] (SSHD-921) OutOfMemory Error in extreme situations

["Zhenliang Su (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/SSHD-921?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16863840#comment-16863840 ] 

Zhenliang Su edited comment on SSHD-921 at 6/14/19 8:45 AM:
------------------------------------------------------------

I think a simple modification is to change the org.apache.sshd.agent.local.AgentForwardedChannel#request function:
{code:java}
protected Buffer request(Buffer buffer) throws IOException {
        synchronized (messages) {
            try {
                OutputStream outputStream = getInvertedIn();
                outputStream.write(buffer.array(), buffer.rpos(), buffer.available());
                outputStream.flush();

                Window wLocal = getLocalWindow();
                wLocal.consumeAndCheck(buffer.available());
                if (messages.isEmpty()) {
                    long start = System.currentTimeMillis();
                    long authTimeout = getLongProperty(FactoryManager.AUTH_TIMEOUT, FactoryManager.DEFAULT_AUTH_TIMEOUT);
                    messages.wait(authTimeout + 2000); // The 2000 here is just for a little longer.
                    long end = System.currentTimeMillis();
                    if (end - start > authTimeout) {
                    	throw new IOException("wait timeout");
                    }
                }
                return messages.poll();
            } catch (InterruptedException e) {
                throw (IOException) new InterruptedIOException("Interrupted while polling for messages").initCause(e);
            }
        }
    }
{code}


was (Author: smoking):
I think a simple modification is to change the org.apache.sshd.agent.local.AgentForwardedChannel#request function:
{code:java}
protected Buffer request(Buffer buffer) throws IOException {
        synchronized (messages) {
            try {
                OutputStream outputStream = getInvertedIn();
                outputStream.write(buffer.array(), buffer.rpos(), buffer.available());
                outputStream.flush();

                Window wLocal = getLocalWindow();
                wLocal.consumeAndCheck(buffer.available());
                if (messages.isEmpty()) {
                	long start = System.currentTimeMillis();
                	long authTimeout = getLongProperty(FactoryManager.AUTH_TIMEOUT, FactoryManager.DEFAULT_AUTH_TIMEOUT);
                    messages.wait(authTimeout + 2000); // The 2000 here is just for a little longer.
                    long end = System.currentTimeMillis();
                    if (end - start > authTimeout) {
                    	throw new IOException("wait timeout");
                    }
                }
                return messages.poll();
            } catch (InterruptedException e) {
                throw (IOException) new InterruptedIOException("Interrupted while polling for messages").initCause(e);
            }
        }
    }
{code}

> 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, 2.0.0
>            Reporter: Zhenliang Su
>            Assignee: Goldstein Lyor
>            Priority: Major
>         Attachments: Main.java, jstack.txt
>
>
> The demo code run in my local machine.
>  When I 'ssh root@127.0.0.1 -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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