jmp imm bug

[blackchicken20]

My target address is 0x347486 (0x224AB8A1486), but the generated assembly instruction's target address is 0x347485 (0x224AB8A1485). Is this a bug?

    zasm::Program program(zasm::MachineMode::AMD64);
    zasm::x86::Assembler assembler(program);

    assembler.jmp(zasm::Imm(instr.jmp_rva));

    zasm::Serializer serializer{};
    auto res = serializer.serialize(program, instr.rva);
    if (res == zasm::ErrorCode::None) {
      auto ptr = serializer.getCode();
      auto size = serializer.getCodeSize();
      std::memcpy(reinterpret_cast<void *>(base.module_base + instr.rva),
                  serializer.getCode(), serializer.getCodeSize());
     }
     

[ZehMatt]

I've created a small test function using the information you provided.

    TEST(SerializationTests, Issue_129)
    {
        int64_t rva = 0x3471fe;
        int64_t jmp_rva = 0x347486;

        Program program(zasm::MachineMode::AMD64);
        x86::Assembler assembler(program);

        assembler.jmp(zasm::Imm(jmp_rva));

        zasm::Serializer serializer{};
        auto res = serializer.serialize(program, rva);
        if (res == zasm::ErrorCode::None)
        {
            auto ptr = serializer.getCode();
            auto size = serializer.getCodeSize();

            ASSERT_EQ(size, 5);

            auto decoder = zasm::Decoder(zasm::MachineMode::AMD64);
            auto decoded = decoder.decode(ptr, size, rva);

            auto& op0 = decoded->getOperand<Imm>(0);
            ASSERT_EQ(op0.value<int64_t>(), jmp_rva);
        }
    }

This test however passes on my end, the immediate has the expected value 0x347486. Are you using the latest commit?

[blackchicken20]

I've created a small test function using the information you provided.

    TEST(SerializationTests, Issue_129)
    {
        int64_t rva = 0x3471fe;
        int64_t jmp_rva = 0x347486;

        Program program(zasm::MachineMode::AMD64);
        x86::Assembler assembler(program);

        assembler.jmp(zasm::Imm(jmp_rva));

        zasm::Serializer serializer{};
        auto res = serializer.serialize(program, rva);
        if (res == zasm::ErrorCode::None)
        {
            auto ptr = serializer.getCode();
            auto size = serializer.getCodeSize();

            ASSERT_EQ(size, 5);

            auto decoder = zasm::Decoder(zasm::MachineMode::AMD64);
            auto decoded = decoder.decode(ptr, size, rva);

            auto& op0 = decoded->getOperand<Imm>(0);
            ASSERT_EQ(op0.value<int64_t>(), jmp_rva);
        }
    }

This test however passes on my end, the immediate has the expected value 0x347486. Are you using the latest commit?

yes,i use latest commit.

[blackchicken20]

I created a new project, pulled the commit again, recompiled, and the issue was resolved.
thks @ZehMatt .

[ZehMatt]

Glad it worked out, for good measure I added a new test #130 based on this to prevent such an issue in the future.