Undefined behavior

[umanwizard]

This test segfaults reliably on v0.13.0:

#[cfg(test)]
mod tests {
    use capstone::Capstone;
    use capstone::arch::{BuildsCapstone, DetailsArchInsn};

    #[test]
    fn capstone_segfaults() {
        let cs = Capstone::new()
            .arm64()
            .detail(true)
            .mode(capstone::arch::arm64::ArchMode::Arm)
            .build()
            .unwrap();

        let insns = cs.disasm_all(&[0x0c, 0x44, 0x3b, 0xd5], 0).unwrap();
        for i in insns.as_ref() {
            let id = cs.insn_detail(&i).unwrap();
            let ad = id.arch_detail();
            let aarch = ad.arm64().unwrap();

            println!("{i} (dt: {:?})", aarch.operands().collect::<Vec<_>>());
        }
    }
}

[umanwizard]

This seems to be caused by capstone-engine/capstone#1881

The second operand of this instruction is coming through as type Sys but its value is not one of the variants of Arm64SysOp. And unsafely creating a value whose discriminant is not one of the valid discriminants of the enum type is UB (which manifests here by crashing when we try to print it out).

[jiegec]

The upstream fixes it in the next branch, but we will need to wait for capstone v6 then. You can try the WIP branch at https://github.com/capstone-rust/capstone-rs/tree/capstone-v6.