Usage of .thumb_func crashes Keystone's Python binding on macOS

[ForceBru]

Keystone 0.9.1 (commit 23b54ce)

macOS 10.14.6

---

When I try to assemble this:

.align 1
.thumb
.thumb_func
factorial:
    add r0, r0, #1

...using this Python code:

import keystone as ks 


code = '''
.align 1
.thumb
.thumb_func
factorial:
    add r0, r0, #1
'''

print('Keystone', ks.__version__)
assembler = ks.Ks(ks.KS_ARCH_ARM, ks.KS_MODE_THUMB)

encoding, count = assembler.asm(code)

...Python crashes saying Illegal instruction:

$ python3 keystone_bug2.py
Keystone 0.9.1
Illegal instruction: 4
$

---

The crash log looks like this:

Process:               Python [3202]
Path:                  /Library/Frameworks/Python.framework/Versions/3.7/Resources/Python.app/Contents/MacOS/Python
Identifier:            Python
Version:               3.7.1 (3.7.1)
Code Type:             X86-64 (Native)
Parent Process:        bash [2933]
Responsible:           Electron [783]
User ID:               501

Date/Time:             2020-06-08
OS Version:            Mac OS X 10.14.6 (18G4032)
Report Version:        12
Anonymous UUID:        328A8AA9-3118-54F5-98C1-76C79A44A098


Time Awake Since Boot: 2600 seconds

System Integrity Protection: enabled

Crashed Thread:        0  Dispatch queue: com.apple.main-thread

Exception Type:        EXC_BAD_INSTRUCTION (SIGILL)
Exception Codes:       0x0000000000000001, 0x0000000000000000

Thread 0 Crashed:: Dispatch queue: com.apple.main-thread
0   libkeystone.dylib             	0x0000000100974104 llvm_ks::MCELFStreamer::EmitThumbFunc(llvm_ks::MCSymbol*) + 4
1   libkeystone.dylib             	0x0000000100a2cdcf (anonymous namespace)::ARMAsmParser::onLabelParsed(llvm_ks::MCSymbol*) + 47
2   libkeystone.dylib             	0x000000010098635e (anonymous namespace)::AsmParser::parseStatement((anonymous namespace)::ParseStatementInfo&, llvm_ks::MCAsmParserSemaCallback*, unsigned long long&) + 6638
3   libkeystone.dylib             	0x0000000100980ede (anonymous namespace)::AsmParser::Run(bool, unsigned long long, bool) + 510
4   libkeystone.dylib             	0x0000000100b0d199 ks_asm + 1289
5   _ctypes.cpython-37m-darwin.so 	0x00000001007ba1d7 ffi_call_unix64 + 79
6   _ctypes.cpython-37m-darwin.so 	0x00000001007baa38 ffi_call + 872
7   _ctypes.cpython-37m-darwin.so 	0x00000001007b59fb _ctypes_callproc + 891
8   _ctypes.cpython-37m-darwin.so 	0x00000001007afaf0 PyCFuncPtr_call + 1040
9   org.python.python             	0x00000001001748b1 _PyObject_FastCallKeywords + 433
10  org.python.python             	0x00000001002342f4 call_function + 420
11  org.python.python             	0x0000000100231406 _PyEval_EvalFrameDefault + 25190
12  org.python.python             	0x0000000100234f56 _PyEval_EvalCodeWithName + 2422
13  org.python.python             	0x0000000100174a61 _PyFunction_FastCallKeywords + 257
14  org.python.python             	0x0000000100234432 call_function + 738
15  org.python.python             	0x00000001002313ec _PyEval_EvalFrameDefault + 25164
16  org.python.python             	0x0000000100234f56 _PyEval_EvalCodeWithName + 2422
17  org.python.python             	0x000000010022b0c4 PyEval_EvalCode + 100
18  org.python.python             	0x0000000100268591 PyRun_FileExFlags + 209
19  org.python.python             	0x0000000100267e0a PyRun_SimpleFileExFlags + 890
20  org.python.python             	0x000000010028619b pymain_main + 6827
21  org.python.python             	0x00000001002866ea _Py_UnixMain + 58
22  libdyld.dylib                 	0x00007fff7a0ab3d5 start + 1

Thread 0 crashed with X86 Thread State (64-bit):
  rax: 0x00007fb4cb418430  rbx: 0x00007fb4cb48c8e0  rcx: 0x0000000100cc5970  rdx: 0x0000000000000001
  rdi: 0x00007fb4cb418430  rsi: 0x00007fb4cb897b38  rbp: 0x00007ffeefab3500  rsp: 0x00007ffeefab3500
   r8: 0x00007fb4cb400000   r9: 0x000000000000030d  r10: 0x0000000000000001  r11: 0x0000000100481a00
  r12: 0x0000000000000009  r13: 0x00007fb4cb48c050  r14: 0x00007fb4cb897b38  r15: 0x00007fb4cb48c030
  rip: 0x0000000100974104  rfl: 0x0000000000010202  cr2: 0x0000000100a2cda0
  
Logical CPU:     0
Error Code:      0x00000000
Trap Number:     6


Binary Images:
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