id = 1373
title = "x86 ADOX and ADCX semantic bug"
state = "closed"
created_at = "2022-12-16T06:58:59.266Z"
closed_at = "2023-02-24T15:06:58.959Z"
labels = ["Closed::Fixed", "accel: TCG", "target: i386"]
url = "https://gitlab.com/qemu-project/qemu/-/issues/1373"
host-os = "Windows 10 20H2"
host-arch = "x86"
qemu-version = "7.1.90 (v7.2.0-rc0)"
guest-os = "None"
guest-arch = "x86"
description = """The result of instruction ADOX and ADCX are different from the CPU. The value of one of EFLAGS is different."""
reproduce = """1. Compile this code
```
void main() {
    asm("push 512; popfq;");
    asm("mov rax, 0xffffffff84fdbf24");
    asm("mov rbx, 0xb197d26043bec15d");
    asm("adox eax, ebx");
}
```
2. Execute and compare the result with the CPU. This problem happens with ADCX, too (with CF).
    - CPU
        - OF = 0
    - QEMU
        - OF = 1"""
additional = """This bug is discovered by research conducted by KAIST SoftSec."""