RFR: JDK-8149461: jmap kills process if non-java pid is specified in the command line

[David Holmes]

Gary,

What is the overhead of doing the validation? How do we list VMs? Do we 
need to examine every running process to get the list of VMs? Wouldn't 
it be better to check the given process is a VM rather than checking all 
potential VM processes?

I think there is an onus of responsibility on the user to provide a 
correct pid here, rather than trying to make this foolproof.

Thanks,
David

On 15/02/2019 5:12 am, Gary Adams wrote:
> The following commands present a similar kill process behavior:
>     jcmd
>     jinfo
>     jmap
>     jstack
> 
> The following commands do not attach.
>     jstat sun.jvmstat.monitor.MonitorException "not found"
>     jps no pid arguments
> 
> This update moves the checkJavaPid method into the 
> common/ProcessArgumentsMatcher.java
> and applies the check before the pid is used for an attach operation.
> 
>    Revised webrev: http://cr.openjdk.java.net/~gadams/8149461/webrev.01/
> 
> On 2/14/19, 12:07 PM, Chris Plummer wrote:
>> Hi Gary,
>>
>> What about the other tools that attach to a user specified process. Do 
>> they also have this issue?
>>
>> thanks,
>>
>> Chris
>>
>> On 2/14/19 8:35 AM, Gary Adams wrote:
>>> There is an old reported problem that using jmap on a process that is 
>>> not running
>>> Java could cause the process to terminate. This is due to the SIGQUIT 
>>> used
>>> when attaching to the process.
>>>
>>> It is a fairly simple operation to validate that the pid matches one 
>>> of the known
>>> running Java processes using VirtualMachine.list().
>>>
>>>   Issue: https://bugs.openjdk.java.net/browse/JDK-8149461
>>>
>>> Proposed fix:
>>>
>>> diff --git a/src/jdk.jcmd/share/classes/sun/tools/jmap/JMap.java 
>>> b/src/jdk.jcmd/share/classes/sun/tools/jmap/JMap.java
>>> --- a/src/jdk.jcmd/share/classes/sun/tools/jmap/JMap.java
>>> +++ b/src/jdk.jcmd/share/classes/sun/tools/jmap/JMap.java
>>> @@ -1,5 +1,5 @@
>>>  /*
>>> - * Copyright (c) 2005, 2018, Oracle and/or its affiliates. All 
>>> rights reserved.
>>> + * Copyright (c) 2005, 2019, Oracle and/or its affiliates. All 
>>> rights reserved.
>>>   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
>>>   *
>>>   * This code is free software; you can redistribute it and/or modify it
>>> @@ -30,6 +30,7 @@
>>>  import java.io.InputStream;
>>>  import java.io.UnsupportedEncodingException;
>>>  import java.util.Collection;
>>> +import java.util.List;
>>>
>>>  import com.sun.tools.attach.VirtualMachine;
>>>  import com.sun.tools.attach.VirtualMachineDescriptor;
>>> @@ -125,6 +126,10 @@
>>>      private static void executeCommandForPid(String pid, String 
>>> command, Object ... args)
>>>          throws AttachNotSupportedException, IOException,
>>>                 UnsupportedEncodingException {
>>> +        // Before attaching, confirm that pid is a known Java process
>>> +        if (!checkJavaPid(pid)) {
>>> +            throw new AttachNotSupportedException();
>>> +        }
>>>          VirtualMachine vm = VirtualMachine.attach(pid);
>>>
>>>          // Cast to HotSpotVirtualMachine as this is an
>>> @@ -196,6 +201,19 @@
>>>          executeCommandForPid(pid, "dumpheap", filename, liveopt);
>>>      }
>>>
>>> +    // Check that pid matches a known running Java process
>>> +    static boolean checkJavaPid(String pid) {
>>> +        List<VirtualMachineDescriptor> l = VirtualMachine.list();
>>> +        boolean found = false;
>>> +        for (VirtualMachineDescriptor vmd: l) {
>>> +            if (vmd.id().equals(pid)) {
>>> +                found = true;
>>> +                break;
>>> +            }
>>> +        }
>>> +        return found;
>>> +    }
>>> +
>>>      private static void checkForUnsupportedOptions(String[] args) {
>>>          // Check arguments for -F, -m, and non-numeric value
>>>          // and warn the user that SA is not supported anymore
>>
>>
>