72 lines
1.6 KiB
Python
72 lines
1.6 KiB
Python
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import regress
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from unicorn import *
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from unicorn.x86_const import *
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from capstone import *
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CODE = bytes.fromhex(
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'48 31 c0' # xor rax,rax
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'48 0f c7 f0' # rdrand rax
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'f4' # hlt
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)
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BASE = 0x100000
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PAGE_SIZE = 0x1000
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# max possible length of a x86 instruction
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MAX_INSN_LEN = 15
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def hook_invalid_insn(uc, ud):
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regress.logger.debug('entered invalid instruction handler')
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pc = uc.reg_read(UC_X86_REG_RIP)
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data = uc.mem_read(pc, MAX_INSN_LEN)
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md = Cs(CS_ARCH_X86, CS_MODE_64)
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insn = next(md.disasm(data, pc, 1))
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if insn.mnemonic == 'rdrand':
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# chosen by fair dice roll, guaranteed to be random
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rax = 4
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# set result to rax
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uc.reg_write(UC_X86_REG_RAX, rax)
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# resume emulation from next instruction
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uc.reg_write(UC_X86_REG_RIP, pc + insn.size)
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# signal uc we are ok
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return True
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# not handled, uc will crash
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return False
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class TestHooks(regress.RegressTest):
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def test_invalid_insn_recover(self):
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mu = Uc(UC_ARCH_X86, UC_MODE_64)
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mu.mem_map(BASE, PAGE_SIZE)
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mu.mem_write(BASE, CODE)
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mu.hook_add(UC_HOOK_INSN_INVALID, hook_invalid_insn)
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try:
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mu.emu_start(BASE, BASE + len(CODE))
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except UcError as ex:
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if ex.errno == UC_ERR_INSN_INVALID:
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self.fail('invalid instruction did not recover properly')
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# unexpected exception, re-raise
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raise
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self.assertNotEqual(0, mu.reg_read(UC_X86_REG_RAX))
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if __name__ == '__main__':
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regress.main()
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