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https://issues.apache.org/jira/browse/ZOOKEEPER-2623?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17774123#comment-17774123
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Andor Molnar commented on ZOOKEEPER-2623:
-----------------------------------------
[~tison] [~eolivelli]
Shall we backport this to 3.8 and 3.9?
> CheckVersion outside of Multi causes NullPointerException
> ---------------------------------------------------------
>
> Key: ZOOKEEPER-2623
> URL: https://issues.apache.org/jira/browse/ZOOKEEPER-2623
> Project: ZooKeeper
> Issue Type: Bug
> Reporter: Diego Ongaro
> Assignee: Kezhu Wang
> Priority: Minor
> Labels: pull-request-available
> Fix For: 3.10.0
>
> Time Spent: 1h
> Remaining Estimate: 0h
>
> I wasn't sure if check version (opcode 13) was permitted outside of a multi
> op, so I tried it. My server crashed with a NullPointerException and became
> unusable until restarted. I guess it's not allowed, but perhaps the server
> should handle this more gracefully?
> Here are the server logs:
> {noformat}
> Accepted socket connection from /0:0:0:0:0:0:0:1:51737
> Session establishment request from client /0:0:0:0:0:0:0:1:51737 client's
> lastZxid is 0x0
> Connection request from old client /0:0:0:0:0:0:0:1:51737; will be dropped if
> server is in r-o mode
> Client attempting to establish new session at /0:0:0:0:0:0:0:1:51737
> :Fsessionid:0x10025651faa0000 type:createSession cxid:0x0
> zxid:0xfffffffffffffffe txntype:unknown reqpath:n/a
> Processing request:: sessionid:0x10025651faa0000 type:createSession cxid:0x0
> zxid:0xfffffffffffffffe txntype:unknown reqpath:n/a
> Got zxid 0x60000065e expected 0x1
> Creating new log file: log.60000065e
> Committing request:: sessionid:0x10025651faa0000 type:createSession cxid:0x0
> zxid:0x60000065e txntype:-10 reqpath:n/a
> Processing request:: sessionid:0x10025651faa0000 type:createSession cxid:0x0
> zxid:0x60000065e txntype:-10 reqpath:n/a
> :Esessionid:0x10025651faa0000 type:createSession cxid:0x0 zxid:0x60000065e
> txntype:-10 reqpath:n/a
> sessionid:0x10025651faa0000 type:createSession cxid:0x0 zxid:0x60000065e
> txntype:-10 reqpath:n/a
> Add a buffer to outgoingBuffers, sk sun.nio.ch.SelectionKeyImpl@28e9f397 is
> valid: true
> Established session 0x10025651faa0000 with negotiated timeout 20000 for
> client /0:0:0:0:0:0:0:1:51737
> :Fsessionid:0x10025651faa0000 type:check cxid:0x1 zxid:0xfffffffffffffffe
> txntype:unknown reqpath:/
> Processing request:: sessionid:0x10025651faa0000 type:check cxid:0x1
> zxid:0xfffffffffffffffe txntype:unknown reqpath:/
> Processing request:: sessionid:0x10025651faa0000 type:check cxid:0x1
> zxid:0xfffffffffffffffe txntype:unknown reqpath:/
> Exception causing close of session 0x10025651faa0000: Connection reset by peer
> :Esessionid:0x10025651faa0000 type:check cxid:0x1 zxid:0xfffffffffffffffe
> txntype:unknown reqpath:/
> IOException stack trace
> java.io.IOException: Connection reset by peer
> at sun.nio.ch.FileDispatcherImpl.read0(Native Method)
> at sun.nio.ch.SocketDispatcher.read(SocketDispatcher.java:39)
> at sun.nio.ch.IOUtil.readIntoNativeBuffer(IOUtil.java:223)
> at sun.nio.ch.IOUtil.read(IOUtil.java:197)
> at sun.nio.ch.SocketChannelImpl.read(SocketChannelImpl.java:380)
> at
> org.apache.zookeeper.server.NIOServerCnxn.doIO(NIOServerCnxn.java:320)
> at
> org.apache.zookeeper.server.NIOServerCnxnFactory$IOWorkRequest.doWork(NIOServerCnxnFactory.java:530)
> at
> org.apache.zookeeper.server.WorkerService$ScheduledWorkRequest.run(WorkerService.java:162)
> at
> java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
> at
> java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
> at java.lang.Thread.run(Thread.java:745)
> Unexpected exception
> java.lang.NullPointerException
> at
> org.apache.zookeeper.server.ZKDatabase.addCommittedProposal(ZKDatabase.java:252)
> at
> org.apache.zookeeper.server.FinalRequestProcessor.processRequest(FinalRequestProcessor.java:127)
> at
> org.apache.zookeeper.server.quorum.CommitProcessor$CommitWorkRequest.doWork(CommitProcessor.java:362)
> at
> org.apache.zookeeper.server.WorkerService$ScheduledWorkRequest.run(WorkerService.java:162)
> at
> java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
> at
> java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
> at java.lang.Thread.run(Thread.java:745)
> Committing request:: sessionid:0x10025651faa0000 type:error cxid:0x1
> zxid:0x60000065f txntype:-1 reqpath:n/a
> Unregister MBean
> [org.apache.ZooKeeperService:name0=ReplicatedServer_id1,name1=replica.1,name2=Follower,name3=Connections,name4="0:0:0:0:0:0:0:1",name5=0x10025651faa0000]
> Exception thrown by downstream processor, unable to continue.
> CommitProcessor exited loop!
> Closed socket connection for client /0:0:0:0:0:0:0:1:51737 which had
> sessionid 0x10025651faa0000
> {noformat}
> And here's a one-liner to repro, which does a ConnectRequest followed by a
> {{CheckVersion(path="/", version=89235}}}:
> {noformat}
> echo
> AAAALAAAAAAAAAAAAAAAAAAAJxAAAAAAAAAAAAAAABAAAAAAAAAAAAAAAAAAAAAAAAAAEQAAAAEAAAANAAAAAS8AAVyT
> | base64 --decode | nc localhost 2181 >/dev/null
> {noformat}
> This is against master as of a couple of weeks ago (f78061a). I haven't
> checked to see which versions are affected.
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