id = 1371
title = "x86 BLSMSK semantic bug"
state = "closed"
created_at = "2022-12-16T06:43:29.794Z"
closed_at = "2023-03-01T01:08:38.844Z"
labels = ["Closed::Fixed", "accel: TCG", "target: i386"]
url = "https://gitlab.com/qemu-project/qemu/-/issues/1371"
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 BLSMSK is different with from the CPU. The value of CF is different."""
reproduce = """1. Compile this code
```
void main() {
    asm("mov rax, 0x65b2e276ad27c67");
    asm("mov rbx, 0x62f34955226b2b5d");
    asm("blsmsk eax, ebx");
}
```
2. Execute and compare the result with the CPU.
    - CPU
        - CF = 0
    - QEMU
        - CF = 1"""
additional = """This bug is discovered by research conducted by KAIST SoftSec."""