[jboss-jira] [JBoss JIRA] (JGRP-2271) Race condition in BaseServer.getConnection

[Bela Ban (JIRA)]

    [ https://issues.jboss.org/browse/JGRP-2271?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13591892#comment-13591892 ] 

Bela Ban edited comment on JGRP-2271 at 6/15/18 3:59 AM:
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Hmm, this is a bit more complicated than I thought: {{Socket.isConnected()}} returns true if is has been connected, even if it has been closed later! So the correct condition should be {{if(sock.isConnected() && !sock.isClosed())}} !

This is bad as {{Socket.isClosed()}} acquires {{sockLock}}, which is costly. I guess keeping a {{connected}} variable in {{Connection}} itself, which is set to true on successful connect and false on close, is our best option...


was (Author: belaban):
Hmm, this is a bit more complicated than I thought: Socket.isConnected() returns true if is has been connected, even if it has been closed later! So the correct condition should be {{if(sock.isConnected() && !sock.isClosed())}} !

This is bad as Socket.isClosed() acquired {{sockLock}}, which is costly. I guess keeping a {{connected}} variable in {{Connection}} itself, which is set to true on successful connect and false on close, is our best option...

> Race condition in BaseServer.getConnection
> ------------------------------------------
>
>                 Key: JGRP-2271
>                 URL: https://issues.jboss.org/browse/JGRP-2271
>             Project: JGroups
>          Issue Type: Bug
>    Affects Versions: 3.6.10
>            Reporter: Dennis Reed
>            Assignee: Bela Ban
>             Fix For: 4.0.12, 3.6.16
>
>
> BaseServer.getConnection creates a socket and puts it in the shared map under a lock.
> However it does not connect the socket inside the lock, so another thread calling getConnection at the same time can get the unconnected socket, which will throw a NPE when used because it's not connected yet (all the checks before returning and using it only look for isOpen, not isConnected).
> java.lang.NullPointerException
>     at org.jgroups.blocks.cs.TcpConnection.doSend(TcpConnection.java:184)
>     at org.jgroups.blocks.cs.TcpConnection._send(TcpConnection.java:171)
>     at org.jgroups.blocks.cs.TcpConnection.send(TcpConnection.java:141)
>     at org.jgroups.blocks.cs.BaseServer.send(BaseServer.java:185)



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