amx_fork/threaded crash [Linux]

[yoranjj]

Hey again, not quite sure what the issue here is, but;

I've been looking through the documentation examples and have tried a few. A few work and a few just crash the plugin (server).

Tried using this in a command;

new result;
amx_forked(.result=result)
{
    task_yield(1);
    threaded(sync_explicit)
    {
        thread_sleep(1000);
        print("Thread end");
    }
    print("Fork end"); //after 1 s
}
assert result == 1; //immediately

And I get a crash error;

[01:54:23] [debug] Server crashed due to an unknown error
[01:54:23] [debug] Native backtrace:
[01:54:23] [debug] #0 f72e2371 in _Z13GetStackTraceRSt6vectorI10StackFrameSaIS0_EEPv () from plugins/crashdetect.so
[01:54:23] [debug] #1 f72d996d in _ZN18CrashDetectHandler20PrintNativeBacktraceERSoRKN2os7ContextE () from plugins/crashdetect.so
[01:54:23] [debug] #2 f72da98d in _ZN18CrashDetectHandler20PrintNativeBacktraceERKN2os7ContextE () from plugins/crashdetect.so
[01:54:23] [debug] #3 f72dcd1d in _ZN18CrashDetectHandler7OnCrashERKN2os7ContextE () from plugins/crashdetect.so
[01:54:23] [debug] #4 f72e183c in ?? () from plugins/crashdetect.so
[01:54:23] [debug] #5 f76efbd0 in ?? ()
[01:54:23] [debug] #6 f72dc6aa in _ZN18CrashDetectHandler13HandleAMXExecEPii () from plugins/crashdetect.so
[01:54:23] [debug] #7 f72df999 in ?? () from plugins/crashdetect.so
[01:54:23] [debug] #8 f5964406 in ?? () from plugins/streamer.so
[01:54:23] [debug] #9 f564744c in _Z15amx_ExecContextP6tagAMXPiibPN3amx5resetEb () from plugins/PawnPlus.so
[01:54:23] [debug] #10 f5649154 in _Z15amx_ExecContextP6tagAMXPiibPN3amx5resetEb () from plugins/PawnPlus.so
[01:54:23] [debug] #11 f564b9e6 in _ZN5Hooks8amx_ExecEP6tagAMXPii () from plugins/PawnPlus.so
[01:54:23] [debug] #12 706f7264 in ?? () from D��

[IS4Code]

Hmm, I am not able to reproduce the issue. Can you upload the executable so I can inspect it?

[yoranjj]

If I'm right, you mean the compiled .so file?

PawnPlus.zip

[IS4Code]

The crash is at a regular call to amx_Exec. Does the code crash if you remove the inner threaded block, amx_forked or the streamer? Did the same code also crash for older versions?

[IS4Code]

I also can't test the .so on my server, since it's missing some symbols. Can you build it with make static and send me the .so?

[yoranjj]

So yeah, the code doesn't crash if I remove the amx_forked block.

PawnPlus.zip

[IS4Code]

I can't reproduce the issue even with the .so (which works though). Can you please send me the pwn/amx you are testing with?

[yoranjj]

I would love too, but it is fairly large and requires a lot of includes to compile correctly (going for a "modular" approach). Could it be the command processor (Pawn.CMD) that is interfering with PawnPlus?

[IS4Code]

I don't think the chance is too high, but perhaps you could isolate the issue into a portable filterscript.

You could also test if there is a difference between these pieces of code:

amx_forked(fork_exec)
{
    print("inside");
}

amx_forked(fork_data)
{
    print("inside");
}

amx_forked(fork_machine)
{
    print("inside");
}

[yoranjj]

Yeah, I just found out that it isn't caused by Pawn.CMD. Tried all of the pieces of code you listed and the only one that didn't crash (tested in main()) was fork_data, odd.

[IS4Code]

Strange... Do you have other plugins that could affect the crash, like JIT for example? Does wait_ms work?

[yoranjj]

wait_ms does work, I'm using the following plugins;

crashdetect.so pawn-redis.so pawncmd.so pawnregex.so pawnraknet.so pawn-memory.so mysql.so sscanf.so streamer.so YSF.so CVector.so PawnPlus.so

[yoranjj]

Okay, apparently crashdetect was the issue, which is weird because it just installs crash handlers and only gets called when a fatal error occurs... so odd.

[IS4Code]

crashdetect replaces the implementation of AMX with its own, so it basically controls every execution. I was probably using a version which doesn't cause an issue. Mine is CrashDetect v4.15.1.

[IS4Code]

Okay, I have downloaded the latest version of CrashDetect and now I can reproduce the crash on Windows as well. Thanks for reporting!

[yoranjj]

Anytime! I'll be downgrading to v4.15.1 for now, thanks for the help!

[IS4Code]

If you can compile the latest commit of CrashDetect, can you check please if it works on Linux for you?

[yoranjj]

Yup, all good now, compiled the latest commit of CrashDetect and used the version of PawnPlus that I statically compiled a way back when we were debugging this.

EDIT: Just wanted to apologize for making you wait this long, busy with something else.