Author eryksun
Recipients Big Stone, eryksun, paul.moore, roger.serwy, steve.dower, terry.reedy, tim.golden, zach.ware
Date 2016-10-27.06:36:21
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Marked as misclassified Yes
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You may have uncovered a bug in Python that's causing the invalid parameter handler to be invoked. It would help if you uploaded the zipped dump file for the crashed process. 

The status code you're getting (i.e. STATUS_STACK_BUFFER_OVERRUN, 0xC0000409) is used by the __fastfail intrinsic [1]. The exception occurred in ucrtbase.dll at offset 0x6d5b8. In a debugger you can see it's in the CRT's invoke_watson function:

    0:000> u ucrtbase + 0x6d5b8 - 0x18 L7
    00007ffd`8984d5a0 4883ec28        sub     rsp,28h
    00007ffd`8984d5a4 b917000000      mov     ecx,17h
    00007ffd`8984d5a9 ff1531310400    call    qword ptr
        [ucrtbase!_imp_IsProcessorFeaturePresent (00007ffd`898906e0)]
    00007ffd`8984d5af 85c0            test    eax,eax
    00007ffd`8984d5b1 7407            je      ucrtbase!invoke_watson+0x1a
    00007ffd`8984d5b3 b905000000      mov     ecx,5
    00007ffd`8984d5b8 cd29            int     29h

A fast fail executes an int 29h software interrupt, which gets handled by the following system function:

    lkd> !idt 0x29
    Dumping IDT: fffff801819a8070
    29:     fffff8017fd66680 nt!KiRaiseSecurityCheckFailure

In this case the CRT passes a value of 5 (FAST_FAIL_INVALID_ARG) in register rcx (ecx), so it's not a critical security failure.

Date User Action Args
2016-10-27 06:36:22eryksunsetrecipients: + eryksun, terry.reedy, paul.moore, tim.golden, roger.serwy, zach.ware, steve.dower, Big Stone
2016-10-27 06:36:22eryksunsetmessageid: <>
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2016-10-27 06:36:21eryksuncreate