Exception Code: 0xC000001D after `std::__libcpp_thread_create` failure

[m417z]

Hello, I'm the author of the Windhawk project which comes with a bundled package of Clang 20. One of the users reported the following error:

PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace.
Exception Code: 0xC000001D
0x6AA7DDC8, C:\Program Files\Windhawk\Compiler\bin\libLLVM-20.dll(0x000000006A930000) + 0x14DDC8 byte(s), HandleAbort() + 0x8 byte(s)
0x7784C56B, C:\Windows\System32\msvcrt.dll(0x00000000777F0000) + 0x5C56B byte(s), abort() + 0x1B byte(s)
0x66EBE3F7, C:\Program Files\Windhawk\Compiler\bin\libc++.dll(0x0000000066EA0000) + 0x1E3F7 byte(s), _ZNKSt10bad_typeid4whatEv() + 0x67 byte(s)
0x66EA1472, C:\Program Files\Windhawk\Compiler\bin\libc++.dll(0x0000000066EA0000) + 0x1472 byte(s), __cxa_throw_bad_array_new_length() + 0xF2 byte(s)
0x66EBD6CC, C:\Program Files\Windhawk\Compiler\bin\libc++.dll(0x0000000066EA0000) + 0x1D6CC byte(s), _ZSt13get_terminatev() + 0x1C byte(s)
0x66EC05F7, C:\Program Files\Windhawk\Compiler\bin\libc++.dll(0x0000000066EA0000) + 0x205F7 byte(s), __cxa_throw() + 0x57 byte(s)
0x66EC05DE, C:\Program Files\Windhawk\Compiler\bin\libc++.dll(0x0000000066EA0000) + 0x205DE byte(s), __cxa_throw() + 0x3E byte(s)
0x66EE3B2D, C:\Program Files\Windhawk\Compiler\bin\libc++.dll(0x0000000066EA0000) + 0x43B2D byte(s), _ZNSt3__126__write_to_windows_consoleEP6_iobufNS_17basic_string_viewIwNS_11char_traitsIwEEEE() + 0xAD byte(s)
0x66EEF35B, C:\Program Files\Windhawk\Compiler\bin\libc++.dll(0x0000000066EA0000) + 0x4F35B byte(s), _ZNSt3__120__throw_system_errorEiPKc() + 0x2B byte(s)
0x6A9FD1A5, C:\Program Files\Windhawk\Compiler\bin\libLLVM-20.dll(0x000000006A930000) + 0xCD1A5 byte(s), _ZNSt3__16vectorINS_6threadENS_9allocatorIS1_EEE8__appendEj() + 0x585 byte(s)
0x77038E8B, C:\Windows\System32\KERNELBASE.dll(0x0000000076F20000) + 0x118E8B byte(s), FlsGetValue() + 0x1B byte(s)
0x66F3F8D1, C:\Program Files\Windhawk\Compiler\bin\libc++.dll(0x0000000066EA0000) + 0x9F8D1 byte(s), _ZNSt3__122__libcpp_thread_createEPPvPFS0_S0_ES0_() + 0x71 byte(s)
0x77857FB1, C:\Windows\System32\msvcrt.dll(0x00000000777F0000) + 0x67FB1 byte(s), _endthreadex() + 0x91 byte(s)
0x76C067F9, C:\Windows\System32\KERNEL32.DLL(0x0000000076BF0000) + 0x167F9 byte(s), BaseThreadInitThunk() + 0x19 byte(s)
0x77D17F4D, C:\Windows\SYSTEM32\ntdll.dll(0x0000000077CB0000) + 0x67F4D byte(s), RtlGetFullPathName_UEx() + 0xAD byte(s)
0x77D17F1B, C:\Windows\SYSTEM32\ntdll.dll(0x0000000077CB0000) + 0x67F1B byte(s), RtlGetFullPathName_UEx() + 0x7B byte(s)
clang-20: error: linker command failed due to signal (use -v to see invocation)

Per the error message request, I'm reporting it here. I suspect it might be an OOM error, in which case it's probably not a bug, but the error handling and the error message could be impoved.

[frederick-vs-ja]

Could you try LLVM 21 or trunk?

I fixed the title to say std::vector<std::thread>::__append as there's no std::vector::append function. It's not very clear whether the error came from it. Many function names shown in the stacktrace were inappropriate because the error probably came from functions of internal linkage whose names are excluded from the debug symbols.

[llvmbot]

@llvm/issue-subscribers-lld-coff

Author: Michael Maltsev (m417z)

Hello, I'm the author of the Windhawk project which comes with a bundled package of Clang 20. One of the users [reported the following error](https://github.com/ramensoftware/windhawk/issues/622):

PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace.
Exception Code: 0xC000001D
0x6AA7DDC8, C:\Program Files\Windhawk\Compiler\bin\libLLVM-20.dll(0x000000006A930000) + 0x14DDC8 byte(s), HandleAbort() + 0x8 byte(s)
0x7784C56B, C:\Windows\System32\msvcrt.dll(0x00000000777F0000) + 0x5C56B byte(s), abort() + 0x1B byte(s)
0x66EBE3F7, C:\Program Files\Windhawk\Compiler\bin\libc++.dll(0x0000000066EA0000) + 0x1E3F7 byte(s), _ZNKSt10bad_typeid4whatEv() + 0x67 byte(s)
0x66EA1472, C:\Program Files\Windhawk\Compiler\bin\libc++.dll(0x0000000066EA0000) + 0x1472 byte(s), __cxa_throw_bad_array_new_length() + 0xF2 byte(s)
0x66EBD6CC, C:\Program Files\Windhawk\Compiler\bin\libc++.dll(0x0000000066EA0000) + 0x1D6CC byte(s), _ZSt13get_terminatev() + 0x1C byte(s)
0x66EC05F7, C:\Program Files\Windhawk\Compiler\bin\libc++.dll(0x0000000066EA0000) + 0x205F7 byte(s), __cxa_throw() + 0x57 byte(s)
0x66EC05DE, C:\Program Files\Windhawk\Compiler\bin\libc++.dll(0x0000000066EA0000) + 0x205DE byte(s), __cxa_throw() + 0x3E byte(s)
0x66EE3B2D, C:\Program Files\Windhawk\Compiler\bin\libc++.dll(0x0000000066EA0000) + 0x43B2D byte(s), _ZNSt3__126__write_to_windows_consoleEP6_iobufNS_17basic_string_viewIwNS_11char_traitsIwEEEE() + 0xAD byte(s)
0x66EEF35B, C:\Program Files\Windhawk\Compiler\bin\libc++.dll(0x0000000066EA0000) + 0x4F35B byte(s), _ZNSt3__120__throw_system_errorEiPKc() + 0x2B byte(s)
0x6A9FD1A5, C:\Program Files\Windhawk\Compiler\bin\libLLVM-20.dll(0x000000006A930000) + 0xCD1A5 byte(s), _ZNSt3__16vectorINS_6threadENS_9allocatorIS1_EEE8__appendEj() + 0x585 byte(s)
0x77038E8B, C:\Windows\System32\KERNELBASE.dll(0x0000000076F20000) + 0x118E8B byte(s), FlsGetValue() + 0x1B byte(s)
0x66F3F8D1, C:\Program Files\Windhawk\Compiler\bin\libc++.dll(0x0000000066EA0000) + 0x9F8D1 byte(s), _ZNSt3__122__libcpp_thread_createEPPvPFS0_S0_ES0_() + 0x71 byte(s)
0x77857FB1, C:\Windows\System32\msvcrt.dll(0x00000000777F0000) + 0x67FB1 byte(s), _endthreadex() + 0x91 byte(s)
0x76C067F9, C:\Windows\System32\KERNEL32.DLL(0x0000000076BF0000) + 0x167F9 byte(s), BaseThreadInitThunk() + 0x19 byte(s)
0x77D17F4D, C:\Windows\SYSTEM32\ntdll.dll(0x0000000077CB0000) + 0x67F4D byte(s), RtlGetFullPathName_UEx() + 0xAD byte(s)
0x77D17F1B, C:\Windows\SYSTEM32\ntdll.dll(0x0000000077CB0000) + 0x67F1B byte(s), RtlGetFullPathName_UEx() + 0x7B byte(s)
clang-20: error: linker command failed due to signal (use -v to see invocation)

Per the error message request, I'm reporting it here. I suspect it might be an OOM error, in which case it's probably not a bug, but the error handling and the error message could be impoved.

[m417z]

@cwlnet are you willing to try LLVM 21? Let me know, and I'll provide detailed instructions for testing it.

[mstorsjo]

The backtrace in itself doesn't really give much actionable unfortunately. Is the issue reproducible? If so, it can be made reproducible for others by building a repro package, by passing e.g. -Wl,--reproduce=repro.tar when linking, which produces a bundle with all the input files and the command line parameters. If all input files are shareable, this should then allow anybody else to reproduce the issue, making it much more feasible to analyze and potentially fix or workaround.

[m417z]

Is the issue reproducible?

It seems to be reproducible for the user, see ramensoftware/windhawk#622.

0xC000001D means STATUS_ILLEGAL_INSTRUCTION, so I wonder if perhaps it's related to the processor model and its instruction set support. From the issue:

Hardware: Gigabyte MZ72-HB0 rev. 3.0, 2x AMD EPYC 7H12.

[mstorsjo]

Is the issue reproducible?

It seems to be reproducible for the user, see ramensoftware/windhawk#622.

0xC000001D means STATUS_ILLEGAL_INSTRUCTION, so I wonder if perhaps it's related to the processor model and its instruction set support. From the issue:

Indeed, that's possibly a reason. In that case, it would be interesting to look at the linking process in a debugger.

Although from the backtrace, it looks like something more of a functional issue, given the __cxa_throw_bad_array_new_length and so on...

[m417z]

I checked this address in the binary:

0x6A9FD1A5, C:\Program Files\Windhawk\Compiler\bin\libLLVM-20.dll(0x000000006A930000) + 0xCD1A5 byte(s), _ZNSt3__16vectorINS_6threadENS_9allocatorIS1_EEE8__appendEj() + 0x585 byte(s)

std::vector<std::thread>::__append indeed seems to be the wrong symbol, the offset is quite large.

The disassembly at this offset is:

5647D19A  | 68 A37D1C59                   | push libllvm-20.591C7DA3                                             | 591C7DA3:"thread constructor failed"
5647D19F  | 50                            | push eax                                                             |
5647D1A0  | E8 F1EAD302                   | call <JMP.&std::__1::__throw_system_error(int, char const*)>         |
5647D1A5  | E8 66FAFFFF                   | call libllvm-20.5647CC10                                             |
5647D1AA  | E8 B1FEF5FF                   | call libllvm-20.563DD060                                             |

Which is the thread constructor, I assume here:

llvm-project/libcxx/include/__thread/thread.h

Line 216 in 96688d4

__throw_system_error(__ec, "thread constructor failed");

It seems that std::__libcpp_thread_create fails for some reason.