RFR: 8342449: reimplement: JDK-8327114 Attach in Linux may have wrong behavior when pid == ns_pid [v3]

[Serguei Spitsyn]

On Thu, 7 Nov 2024 04:48:28 GMT, Serguei Spitsyn <sspitsyn at openjdk.org> wrote:

>> Larry Cable has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   JDK-8342449: fixed missing param in throws msg and renamed local var
>
> src/jdk.attach/linux/classes/sun/tools/attach/VirtualMachineImpl.java line 268:
> 
>> 266:          * however we can also check the target pid's signal masks to see if it catches SIGQUIT and only do so if in
>> 267:          * fact it does ... this reduces the risk of killing an innocent process in the current ns as opposed to
>> 268:          * attaching to the actual target JVM ... c.f: checkCatchesAndSendQuitTo() below.
> 
> This still looks pretty risky and dangerous. I'm thinking if it'd make sense to check that the target process is a VM process. At least, we know how VM processes can use the signal mask. Another concern is that the target VM process might be not exactly the same VM the client was expecting to attach. I don't know what can be done to ensure this correctness.

It should be okay to file a bug/rfe on this.

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PR Review Comment: https://git.openjdk.org/jdk/pull/21688#discussion_r1838967163