alidate the operand passed to is_val_statically_known

Author: RalfJung

src/tools/miri/src/shims/intrinsics/mod.rs

@@ -148,7 +148,8 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
             // ```
             // Would not be considered UB, or the other way around (`is_val_statically_known(0)`).
             "is_val_statically_known" => {
-                let [_] = check_arg_count(args)?;
+                let [arg] = check_arg_count(args)?;
+                this.validate_operand(arg)?;
                 let branch: bool = this.machine.rng.get_mut().gen();
                 this.write_scalar(Scalar::from_bool(branch), dest)?;
             }