Rename rustc_mir to rustc_const_eval.
This commit is contained in:
Camille GILLOT
965
compiler/rustc_const_eval/src/interpret/validity.rs
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965
compiler/rustc_const_eval/src/interpret/validity.rs
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@@ -0,0 +1,965 @@
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//! Check the validity invariant of a given value, and tell the user
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//! where in the value it got violated.
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//! In const context, this goes even further and tries to approximate const safety.
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//! That's useful because it means other passes (e.g. promotion) can rely on `const`s
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//! to be const-safe.
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use std::convert::TryFrom;
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use std::fmt::Write;
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use std::num::NonZeroUsize;
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use rustc_data_structures::fx::FxHashSet;
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use rustc_hir as hir;
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use rustc_middle::mir::interpret::InterpError;
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use rustc_middle::ty;
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use rustc_middle::ty::layout::{LayoutOf, TyAndLayout};
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use rustc_span::symbol::{sym, Symbol};
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use rustc_target::abi::{Abi, Scalar as ScalarAbi, Size, VariantIdx, Variants, WrappingRange};
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use std::hash::Hash;
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use super::{
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alloc_range, CheckInAllocMsg, GlobalAlloc, InterpCx, InterpResult, MPlaceTy, Machine,
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MemPlaceMeta, OpTy, ScalarMaybeUninit, ValueVisitor,
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};
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macro_rules! throw_validation_failure {
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($where:expr, { $( $what_fmt:expr ),+ } $( expected { $( $expected_fmt:expr ),+ } )?) => {{
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let mut msg = String::new();
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msg.push_str("encountered ");
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write!(&mut msg, $($what_fmt),+).unwrap();
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$(
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msg.push_str(", but expected ");
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write!(&mut msg, $($expected_fmt),+).unwrap();
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)?
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let path = rustc_middle::ty::print::with_no_trimmed_paths(|| {
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let where_ = &$where;
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if !where_.is_empty() {
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let mut path = String::new();
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write_path(&mut path, where_);
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Some(path)
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} else {
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None
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}
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});
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throw_ub!(ValidationFailure { path, msg })
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}};
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}
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/// If $e throws an error matching the pattern, throw a validation failure.
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/// Other errors are passed back to the caller, unchanged -- and if they reach the root of
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/// the visitor, we make sure only validation errors and `InvalidProgram` errors are left.
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/// This lets you use the patterns as a kind of validation list, asserting which errors
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/// can possibly happen:
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///
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/// ```
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/// let v = try_validation!(some_fn(), some_path, {
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/// Foo | Bar | Baz => { "some failure" },
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/// });
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/// ```
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///
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/// An additional expected parameter can also be added to the failure message:
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///
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/// ```
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/// let v = try_validation!(some_fn(), some_path, {
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/// Foo | Bar | Baz => { "some failure" } expected { "something that wasn't a failure" },
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/// });
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/// ```
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///
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/// An additional nicety is that both parameters actually take format args, so you can just write
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/// the format string in directly:
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///
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/// ```
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/// let v = try_validation!(some_fn(), some_path, {
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/// Foo | Bar | Baz => { "{:?}", some_failure } expected { "{}", expected_value },
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/// });
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/// ```
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///
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macro_rules! try_validation {
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($e:expr, $where:expr,
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$( $( $p:pat )|+ => { $( $what_fmt:expr ),+ } $( expected { $( $expected_fmt:expr ),+ } )? ),+ $(,)?
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) => {{
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match $e {
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Ok(x) => x,
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// We catch the error and turn it into a validation failure. We are okay with
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// allocation here as this can only slow down builds that fail anyway.
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Err(e) => match e.kind() {
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$(
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$($p)|+ =>
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throw_validation_failure!(
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$where,
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{ $( $what_fmt ),+ } $( expected { $( $expected_fmt ),+ } )?
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)
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),+,
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#[allow(unreachable_patterns)]
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_ => Err::<!, _>(e)?,
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}
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}
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}};
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}
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/// We want to show a nice path to the invalid field for diagnostics,
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/// but avoid string operations in the happy case where no error happens.
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/// So we track a `Vec<PathElem>` where `PathElem` contains all the data we
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/// need to later print something for the user.
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#[derive(Copy, Clone, Debug)]
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pub enum PathElem {
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Field(Symbol),
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Variant(Symbol),
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GeneratorState(VariantIdx),
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CapturedVar(Symbol),
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ArrayElem(usize),
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TupleElem(usize),
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Deref,
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EnumTag,
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GeneratorTag,
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DynDowncast,
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}
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/// Extra things to check for during validation of CTFE results.
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pub enum CtfeValidationMode {
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/// Regular validation, nothing special happening.
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Regular,
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/// Validation of a `const`.
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/// `inner` says if this is an inner, indirect allocation (as opposed to the top-level const
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/// allocation). Being an inner allocation makes a difference because the top-level allocation
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/// of a `const` is copied for each use, but the inner allocations are implicitly shared.
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/// `allow_static_ptrs` says if pointers to statics are permitted (which is the case for promoteds in statics).
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Const { inner: bool, allow_static_ptrs: bool },
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}
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/// State for tracking recursive validation of references
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pub struct RefTracking<T, PATH = ()> {
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pub seen: FxHashSet<T>,
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pub todo: Vec<(T, PATH)>,
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}
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impl<T: Copy + Eq + Hash + std::fmt::Debug, PATH: Default> RefTracking<T, PATH> {
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pub fn empty() -> Self {
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RefTracking { seen: FxHashSet::default(), todo: vec![] }
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}
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pub fn new(op: T) -> Self {
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let mut ref_tracking_for_consts =
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RefTracking { seen: FxHashSet::default(), todo: vec![(op, PATH::default())] };
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ref_tracking_for_consts.seen.insert(op);
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ref_tracking_for_consts
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}
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pub fn track(&mut self, op: T, path: impl FnOnce() -> PATH) {
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if self.seen.insert(op) {
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trace!("Recursing below ptr {:#?}", op);
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let path = path();
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// Remember to come back to this later.
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self.todo.push((op, path));
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}
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}
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}
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/// Format a path
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fn write_path(out: &mut String, path: &[PathElem]) {
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use self::PathElem::*;
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for elem in path.iter() {
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match elem {
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Field(name) => write!(out, ".{}", name),
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EnumTag => write!(out, ".<enum-tag>"),
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Variant(name) => write!(out, ".<enum-variant({})>", name),
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GeneratorTag => write!(out, ".<generator-tag>"),
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GeneratorState(idx) => write!(out, ".<generator-state({})>", idx.index()),
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CapturedVar(name) => write!(out, ".<captured-var({})>", name),
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TupleElem(idx) => write!(out, ".{}", idx),
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ArrayElem(idx) => write!(out, "[{}]", idx),
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// `.<deref>` does not match Rust syntax, but it is more readable for long paths -- and
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// some of the other items here also are not Rust syntax. Actually we can't
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// even use the usual syntax because we are just showing the projections,
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// not the root.
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Deref => write!(out, ".<deref>"),
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DynDowncast => write!(out, ".<dyn-downcast>"),
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}
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.unwrap()
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}
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}
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// Formats such that a sentence like "expected something {}" to mean
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// "expected something <in the given range>" makes sense.
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fn wrapping_range_format(r: WrappingRange, max_hi: u128) -> String {
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let WrappingRange { start: lo, end: hi } = r;
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assert!(hi <= max_hi);
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if lo > hi {
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format!("less or equal to {}, or greater or equal to {}", hi, lo)
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} else if lo == hi {
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format!("equal to {}", lo)
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} else if lo == 0 {
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assert!(hi < max_hi, "should not be printing if the range covers everything");
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format!("less or equal to {}", hi)
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} else if hi == max_hi {
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assert!(lo > 0, "should not be printing if the range covers everything");
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format!("greater or equal to {}", lo)
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} else {
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format!("in the range {:?}", r)
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}
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}
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struct ValidityVisitor<'rt, 'mir, 'tcx, M: Machine<'mir, 'tcx>> {
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/// The `path` may be pushed to, but the part that is present when a function
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/// starts must not be changed! `visit_fields` and `visit_array` rely on
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/// this stack discipline.
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path: Vec<PathElem>,
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ref_tracking: Option<&'rt mut RefTracking<MPlaceTy<'tcx, M::PointerTag>, Vec<PathElem>>>,
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/// `None` indicates this is not validating for CTFE (but for runtime).
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ctfe_mode: Option<CtfeValidationMode>,
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ecx: &'rt InterpCx<'mir, 'tcx, M>,
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}
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impl<'rt, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> ValidityVisitor<'rt, 'mir, 'tcx, M> {
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fn aggregate_field_path_elem(&mut self, layout: TyAndLayout<'tcx>, field: usize) -> PathElem {
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// First, check if we are projecting to a variant.
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match layout.variants {
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Variants::Multiple { tag_field, .. } => {
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if tag_field == field {
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return match layout.ty.kind() {
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ty::Adt(def, ..) if def.is_enum() => PathElem::EnumTag,
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ty::Generator(..) => PathElem::GeneratorTag,
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_ => bug!("non-variant type {:?}", layout.ty),
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};
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}
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}
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Variants::Single { .. } => {}
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}
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// Now we know we are projecting to a field, so figure out which one.
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match layout.ty.kind() {
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// generators and closures.
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ty::Closure(def_id, _) | ty::Generator(def_id, _, _) => {
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let mut name = None;
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// FIXME this should be more descriptive i.e. CapturePlace instead of CapturedVar
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// https://github.com/rust-lang/project-rfc-2229/issues/46
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if let Some(local_def_id) = def_id.as_local() {
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let tables = self.ecx.tcx.typeck(local_def_id);
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if let Some(captured_place) =
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tables.closure_min_captures_flattened(*def_id).nth(field)
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{
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// Sometimes the index is beyond the number of upvars (seen
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// for a generator).
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let var_hir_id = captured_place.get_root_variable();
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let node = self.ecx.tcx.hir().get(var_hir_id);
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if let hir::Node::Binding(pat) = node {
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if let hir::PatKind::Binding(_, _, ident, _) = pat.kind {
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name = Some(ident.name);
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}
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}
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}
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}
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PathElem::CapturedVar(name.unwrap_or_else(|| {
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// Fall back to showing the field index.
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sym::integer(field)
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}))
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}
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// tuples
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ty::Tuple(_) => PathElem::TupleElem(field),
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// enums
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ty::Adt(def, ..) if def.is_enum() => {
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// we might be projecting *to* a variant, or to a field *in* a variant.
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match layout.variants {
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Variants::Single { index } => {
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// Inside a variant
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PathElem::Field(def.variants[index].fields[field].ident.name)
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}
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Variants::Multiple { .. } => bug!("we handled variants above"),
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}
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}
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// other ADTs
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ty::Adt(def, _) => PathElem::Field(def.non_enum_variant().fields[field].ident.name),
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// arrays/slices
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ty::Array(..) | ty::Slice(..) => PathElem::ArrayElem(field),
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// dyn traits
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ty::Dynamic(..) => PathElem::DynDowncast,
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// nothing else has an aggregate layout
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_ => bug!("aggregate_field_path_elem: got non-aggregate type {:?}", layout.ty),
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}
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}
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fn with_elem<R>(
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&mut self,
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elem: PathElem,
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f: impl FnOnce(&mut Self) -> InterpResult<'tcx, R>,
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) -> InterpResult<'tcx, R> {
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// Remember the old state
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let path_len = self.path.len();
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// Record new element
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self.path.push(elem);
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// Perform operation
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let r = f(self)?;
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// Undo changes
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self.path.truncate(path_len);
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// Done
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Ok(r)
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}
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fn check_wide_ptr_meta(
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&mut self,
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meta: MemPlaceMeta<M::PointerTag>,
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pointee: TyAndLayout<'tcx>,
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) -> InterpResult<'tcx> {
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let tail = self.ecx.tcx.struct_tail_erasing_lifetimes(pointee.ty, self.ecx.param_env);
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match tail.kind() {
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ty::Dynamic(..) => {
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let vtable = self.ecx.scalar_to_ptr(meta.unwrap_meta());
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// Direct call to `check_ptr_access_align` checks alignment even on CTFE machines.
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try_validation!(
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self.ecx.memory.check_ptr_access_align(
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vtable,
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3 * self.ecx.tcx.data_layout.pointer_size, // drop, size, align
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self.ecx.tcx.data_layout.pointer_align.abi,
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CheckInAllocMsg::InboundsTest, // will anyway be replaced by validity message
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),
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self.path,
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err_ub!(DanglingIntPointer(..)) |
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err_ub!(PointerUseAfterFree(..)) =>
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{ "dangling vtable pointer in wide pointer" },
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err_ub!(AlignmentCheckFailed { .. }) =>
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{ "unaligned vtable pointer in wide pointer" },
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err_ub!(PointerOutOfBounds { .. }) =>
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{ "too small vtable" },
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);
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try_validation!(
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self.ecx.read_drop_type_from_vtable(vtable),
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self.path,
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err_ub!(DanglingIntPointer(..)) |
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err_ub!(InvalidFunctionPointer(..)) =>
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{ "invalid drop function pointer in vtable (not pointing to a function)" },
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err_ub!(InvalidVtableDropFn(..)) =>
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{ "invalid drop function pointer in vtable (function has incompatible signature)" },
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);
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try_validation!(
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self.ecx.read_size_and_align_from_vtable(vtable),
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self.path,
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err_ub!(InvalidVtableSize) =>
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{ "invalid vtable: size is bigger than largest supported object" },
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err_ub!(InvalidVtableAlignment(msg)) =>
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{ "invalid vtable: alignment {}", msg },
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err_unsup!(ReadPointerAsBytes) => { "invalid size or align in vtable" },
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);
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// FIXME: More checks for the vtable.
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}
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ty::Slice(..) | ty::Str => {
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let _len = try_validation!(
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meta.unwrap_meta().to_machine_usize(self.ecx),
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self.path,
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err_unsup!(ReadPointerAsBytes) => { "non-integer slice length in wide pointer" },
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);
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// We do not check that `len * elem_size <= isize::MAX`:
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// that is only required for references, and there it falls out of the
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// "dereferenceable" check performed by Stacked Borrows.
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}
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ty::Foreign(..) => {
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// Unsized, but not wide.
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}
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_ => bug!("Unexpected unsized type tail: {:?}", tail),
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}
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Ok(())
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}
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/// Check a reference or `Box`.
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fn check_safe_pointer(
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&mut self,
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value: &OpTy<'tcx, M::PointerTag>,
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kind: &str,
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) -> InterpResult<'tcx> {
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let value = try_validation!(
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self.ecx.read_immediate(value),
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self.path,
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err_unsup!(ReadPointerAsBytes) => { "part of a pointer" } expected { "a proper pointer or integer value" },
|
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);
|
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// Handle wide pointers.
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// Check metadata early, for better diagnostics
|
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let place = try_validation!(
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self.ecx.ref_to_mplace(&value),
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self.path,
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err_ub!(InvalidUninitBytes(None)) => { "uninitialized {}", kind },
|
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);
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if place.layout.is_unsized() {
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self.check_wide_ptr_meta(place.meta, place.layout)?;
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}
|
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// Make sure this is dereferenceable and all.
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let size_and_align = try_validation!(
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self.ecx.size_and_align_of_mplace(&place),
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self.path,
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err_ub!(InvalidMeta(msg)) => { "invalid {} metadata: {}", kind, msg },
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);
|
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let (size, align) = size_and_align
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// for the purpose of validity, consider foreign types to have
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// alignment and size determined by the layout (size will be 0,
|
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// alignment should take attributes into account).
|
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.unwrap_or_else(|| (place.layout.size, place.layout.align.abi));
|
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// Direct call to `check_ptr_access_align` checks alignment even on CTFE machines.
|
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try_validation!(
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self.ecx.memory.check_ptr_access_align(
|
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place.ptr,
|
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size,
|
||||
align,
|
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CheckInAllocMsg::InboundsTest, // will anyway be replaced by validity message
|
||||
),
|
||||
self.path,
|
||||
err_ub!(AlignmentCheckFailed { required, has }) =>
|
||||
{
|
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"an unaligned {} (required {} byte alignment but found {})",
|
||||
kind,
|
||||
required.bytes(),
|
||||
has.bytes()
|
||||
},
|
||||
err_ub!(DanglingIntPointer(0, _)) =>
|
||||
{ "a null {}", kind },
|
||||
err_ub!(DanglingIntPointer(i, _)) =>
|
||||
{ "a dangling {} (address 0x{:x} is unallocated)", kind, i },
|
||||
err_ub!(PointerOutOfBounds { .. }) =>
|
||||
{ "a dangling {} (going beyond the bounds of its allocation)", kind },
|
||||
// This cannot happen during const-eval (because interning already detects
|
||||
// dangling pointers), but it can happen in Miri.
|
||||
err_ub!(PointerUseAfterFree(..)) =>
|
||||
{ "a dangling {} (use-after-free)", kind },
|
||||
);
|
||||
// Recursive checking
|
||||
if let Some(ref mut ref_tracking) = self.ref_tracking {
|
||||
// Proceed recursively even for ZST, no reason to skip them!
|
||||
// `!` is a ZST and we want to validate it.
|
||||
// Skip validation entirely for some external statics
|
||||
if let Ok((alloc_id, _offset, _ptr)) = self.ecx.memory.ptr_try_get_alloc(place.ptr) {
|
||||
// not a ZST
|
||||
let alloc_kind = self.ecx.tcx.get_global_alloc(alloc_id);
|
||||
if let Some(GlobalAlloc::Static(did)) = alloc_kind {
|
||||
assert!(!self.ecx.tcx.is_thread_local_static(did));
|
||||
assert!(self.ecx.tcx.is_static(did));
|
||||
if matches!(
|
||||
self.ctfe_mode,
|
||||
Some(CtfeValidationMode::Const { allow_static_ptrs: false, .. })
|
||||
) {
|
||||
// See const_eval::machine::MemoryExtra::can_access_statics for why
|
||||
// this check is so important.
|
||||
// This check is reachable when the const just referenced the static,
|
||||
// but never read it (so we never entered `before_access_global`).
|
||||
throw_validation_failure!(self.path,
|
||||
{ "a {} pointing to a static variable", kind }
|
||||
);
|
||||
}
|
||||
// We skip checking other statics. These statics must be sound by
|
||||
// themselves, and the only way to get broken statics here is by using
|
||||
// unsafe code.
|
||||
// The reasons we don't check other statics is twofold. For one, in all
|
||||
// sound cases, the static was already validated on its own, and second, we
|
||||
// trigger cycle errors if we try to compute the value of the other static
|
||||
// and that static refers back to us.
|
||||
// We might miss const-invalid data,
|
||||
// but things are still sound otherwise (in particular re: consts
|
||||
// referring to statics).
|
||||
return Ok(());
|
||||
}
|
||||
}
|
||||
let path = &self.path;
|
||||
ref_tracking.track(place, || {
|
||||
// We need to clone the path anyway, make sure it gets created
|
||||
// with enough space for the additional `Deref`.
|
||||
let mut new_path = Vec::with_capacity(path.len() + 1);
|
||||
new_path.clone_from(path);
|
||||
new_path.push(PathElem::Deref);
|
||||
new_path
|
||||
});
|
||||
}
|
||||
Ok(())
|
||||
}
|
||||
|
||||
fn read_scalar(
|
||||
&self,
|
||||
op: &OpTy<'tcx, M::PointerTag>,
|
||||
) -> InterpResult<'tcx, ScalarMaybeUninit<M::PointerTag>> {
|
||||
Ok(try_validation!(
|
||||
self.ecx.read_scalar(op),
|
||||
self.path,
|
||||
err_unsup!(ReadPointerAsBytes) => { "(potentially part of) a pointer" } expected { "plain (non-pointer) bytes" },
|
||||
))
|
||||
}
|
||||
|
||||
/// Check if this is a value of primitive type, and if yes check the validity of the value
|
||||
/// at that type. Return `true` if the type is indeed primitive.
|
||||
fn try_visit_primitive(
|
||||
&mut self,
|
||||
value: &OpTy<'tcx, M::PointerTag>,
|
||||
) -> InterpResult<'tcx, bool> {
|
||||
// Go over all the primitive types
|
||||
let ty = value.layout.ty;
|
||||
match ty.kind() {
|
||||
ty::Bool => {
|
||||
let value = self.read_scalar(value)?;
|
||||
try_validation!(
|
||||
value.to_bool(),
|
||||
self.path,
|
||||
err_ub!(InvalidBool(..)) | err_ub!(InvalidUninitBytes(None)) =>
|
||||
{ "{}", value } expected { "a boolean" },
|
||||
);
|
||||
Ok(true)
|
||||
}
|
||||
ty::Char => {
|
||||
let value = self.read_scalar(value)?;
|
||||
try_validation!(
|
||||
value.to_char(),
|
||||
self.path,
|
||||
err_ub!(InvalidChar(..)) | err_ub!(InvalidUninitBytes(None)) =>
|
||||
{ "{}", value } expected { "a valid unicode scalar value (in `0..=0x10FFFF` but not in `0xD800..=0xDFFF`)" },
|
||||
);
|
||||
Ok(true)
|
||||
}
|
||||
ty::Float(_) | ty::Int(_) | ty::Uint(_) => {
|
||||
let value = self.read_scalar(value)?;
|
||||
// NOTE: Keep this in sync with the array optimization for int/float
|
||||
// types below!
|
||||
if self.ctfe_mode.is_some() {
|
||||
// Integers/floats in CTFE: Must be scalar bits, pointers are dangerous
|
||||
let is_bits = value.check_init().map_or(false, |v| v.try_to_int().is_ok());
|
||||
if !is_bits {
|
||||
throw_validation_failure!(self.path,
|
||||
{ "{}", value } expected { "initialized plain (non-pointer) bytes" }
|
||||
)
|
||||
}
|
||||
} else {
|
||||
// At run-time, for now, we accept *anything* for these types, including
|
||||
// uninit. We should fix that, but let's start low.
|
||||
}
|
||||
Ok(true)
|
||||
}
|
||||
ty::RawPtr(..) => {
|
||||
// We are conservative with uninit for integers, but try to
|
||||
// actually enforce the strict rules for raw pointers (mostly because
|
||||
// that lets us re-use `ref_to_mplace`).
|
||||
let place = try_validation!(
|
||||
self.ecx.read_immediate(value).and_then(|ref i| self.ecx.ref_to_mplace(i)),
|
||||
self.path,
|
||||
err_ub!(InvalidUninitBytes(None)) => { "uninitialized raw pointer" },
|
||||
err_unsup!(ReadPointerAsBytes) => { "part of a pointer" } expected { "a proper pointer or integer value" },
|
||||
);
|
||||
if place.layout.is_unsized() {
|
||||
self.check_wide_ptr_meta(place.meta, place.layout)?;
|
||||
}
|
||||
Ok(true)
|
||||
}
|
||||
ty::Ref(_, ty, mutbl) => {
|
||||
if matches!(self.ctfe_mode, Some(CtfeValidationMode::Const { .. }))
|
||||
&& *mutbl == hir::Mutability::Mut
|
||||
{
|
||||
// A mutable reference inside a const? That does not seem right (except if it is
|
||||
// a ZST).
|
||||
let layout = self.ecx.layout_of(ty)?;
|
||||
if !layout.is_zst() {
|
||||
throw_validation_failure!(self.path, { "mutable reference in a `const`" });
|
||||
}
|
||||
}
|
||||
self.check_safe_pointer(value, "reference")?;
|
||||
Ok(true)
|
||||
}
|
||||
ty::Adt(def, ..) if def.is_box() => {
|
||||
self.check_safe_pointer(value, "box")?;
|
||||
Ok(true)
|
||||
}
|
||||
ty::FnPtr(_sig) => {
|
||||
let value = try_validation!(
|
||||
self.ecx.read_immediate(value),
|
||||
self.path,
|
||||
err_unsup!(ReadPointerAsBytes) => { "part of a pointer" } expected { "a proper pointer or integer value" },
|
||||
);
|
||||
// Make sure we print a `ScalarMaybeUninit` (and not an `ImmTy`) in the error
|
||||
// message below.
|
||||
let value = value.to_scalar_or_uninit();
|
||||
let _fn = try_validation!(
|
||||
value.check_init().and_then(|ptr| self.ecx.memory.get_fn(self.ecx.scalar_to_ptr(ptr))),
|
||||
self.path,
|
||||
err_ub!(DanglingIntPointer(..)) |
|
||||
err_ub!(InvalidFunctionPointer(..)) |
|
||||
err_ub!(InvalidUninitBytes(None)) =>
|
||||
{ "{}", value } expected { "a function pointer" },
|
||||
);
|
||||
// FIXME: Check if the signature matches
|
||||
Ok(true)
|
||||
}
|
||||
ty::Never => throw_validation_failure!(self.path, { "a value of the never type `!`" }),
|
||||
ty::Foreign(..) | ty::FnDef(..) => {
|
||||
// Nothing to check.
|
||||
Ok(true)
|
||||
}
|
||||
// The above should be all the primitive types. The rest is compound, we
|
||||
// check them by visiting their fields/variants.
|
||||
ty::Adt(..)
|
||||
| ty::Tuple(..)
|
||||
| ty::Array(..)
|
||||
| ty::Slice(..)
|
||||
| ty::Str
|
||||
| ty::Dynamic(..)
|
||||
| ty::Closure(..)
|
||||
| ty::Generator(..) => Ok(false),
|
||||
// Some types only occur during typechecking, they have no layout.
|
||||
// We should not see them here and we could not check them anyway.
|
||||
ty::Error(_)
|
||||
| ty::Infer(..)
|
||||
| ty::Placeholder(..)
|
||||
| ty::Bound(..)
|
||||
| ty::Param(..)
|
||||
| ty::Opaque(..)
|
||||
| ty::Projection(..)
|
||||
| ty::GeneratorWitness(..) => bug!("Encountered invalid type {:?}", ty),
|
||||
}
|
||||
}
|
||||
|
||||
fn visit_scalar(
|
||||
&mut self,
|
||||
op: &OpTy<'tcx, M::PointerTag>,
|
||||
scalar_layout: &ScalarAbi,
|
||||
) -> InterpResult<'tcx> {
|
||||
let value = self.read_scalar(op)?;
|
||||
let valid_range = scalar_layout.valid_range.clone();
|
||||
let WrappingRange { start: lo, end: hi } = valid_range;
|
||||
// Determine the allowed range
|
||||
// `max_hi` is as big as the size fits
|
||||
let max_hi = u128::MAX >> (128 - op.layout.size.bits());
|
||||
assert!(hi <= max_hi);
|
||||
// We could also write `(hi + 1) % (max_hi + 1) == lo` but `max_hi + 1` overflows for `u128`
|
||||
if (lo == 0 && hi == max_hi) || (hi + 1 == lo) {
|
||||
// Nothing to check
|
||||
return Ok(());
|
||||
}
|
||||
// At least one value is excluded. Get the bits.
|
||||
let value = try_validation!(
|
||||
value.check_init(),
|
||||
self.path,
|
||||
err_ub!(InvalidUninitBytes(None)) => { "{}", value }
|
||||
expected { "something {}", wrapping_range_format(valid_range, max_hi) },
|
||||
);
|
||||
let bits = match value.try_to_int() {
|
||||
Err(_) => {
|
||||
// So this is a pointer then, and casting to an int failed.
|
||||
// Can only happen during CTFE.
|
||||
let ptr = self.ecx.scalar_to_ptr(value);
|
||||
if lo == 1 && hi == max_hi {
|
||||
// Only null is the niche. So make sure the ptr is NOT null.
|
||||
if self.ecx.memory.ptr_may_be_null(ptr) {
|
||||
throw_validation_failure!(self.path,
|
||||
{ "a potentially null pointer" }
|
||||
expected {
|
||||
"something that cannot possibly fail to be {}",
|
||||
wrapping_range_format(valid_range, max_hi)
|
||||
}
|
||||
)
|
||||
}
|
||||
return Ok(());
|
||||
} else {
|
||||
// Conservatively, we reject, because the pointer *could* have a bad
|
||||
// value.
|
||||
throw_validation_failure!(self.path,
|
||||
{ "a pointer" }
|
||||
expected {
|
||||
"something that cannot possibly fail to be {}",
|
||||
wrapping_range_format(valid_range, max_hi)
|
||||
}
|
||||
)
|
||||
}
|
||||
}
|
||||
Ok(int) => int.assert_bits(op.layout.size),
|
||||
};
|
||||
// Now compare. This is slightly subtle because this is a special "wrap-around" range.
|
||||
if valid_range.contains(bits) {
|
||||
Ok(())
|
||||
} else {
|
||||
throw_validation_failure!(self.path,
|
||||
{ "{}", bits }
|
||||
expected { "something {}", wrapping_range_format(valid_range, max_hi) }
|
||||
)
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
impl<'rt, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> ValueVisitor<'mir, 'tcx, M>
|
||||
for ValidityVisitor<'rt, 'mir, 'tcx, M>
|
||||
{
|
||||
type V = OpTy<'tcx, M::PointerTag>;
|
||||
|
||||
#[inline(always)]
|
||||
fn ecx(&self) -> &InterpCx<'mir, 'tcx, M> {
|
||||
&self.ecx
|
||||
}
|
||||
|
||||
fn read_discriminant(
|
||||
&mut self,
|
||||
op: &OpTy<'tcx, M::PointerTag>,
|
||||
) -> InterpResult<'tcx, VariantIdx> {
|
||||
self.with_elem(PathElem::EnumTag, move |this| {
|
||||
Ok(try_validation!(
|
||||
this.ecx.read_discriminant(op),
|
||||
this.path,
|
||||
err_ub!(InvalidTag(val)) =>
|
||||
{ "{}", val } expected { "a valid enum tag" },
|
||||
err_ub!(InvalidUninitBytes(None)) =>
|
||||
{ "uninitialized bytes" } expected { "a valid enum tag" },
|
||||
err_unsup!(ReadPointerAsBytes) =>
|
||||
{ "a pointer" } expected { "a valid enum tag" },
|
||||
)
|
||||
.1)
|
||||
})
|
||||
}
|
||||
|
||||
#[inline]
|
||||
fn visit_field(
|
||||
&mut self,
|
||||
old_op: &OpTy<'tcx, M::PointerTag>,
|
||||
field: usize,
|
||||
new_op: &OpTy<'tcx, M::PointerTag>,
|
||||
) -> InterpResult<'tcx> {
|
||||
let elem = self.aggregate_field_path_elem(old_op.layout, field);
|
||||
self.with_elem(elem, move |this| this.visit_value(new_op))
|
||||
}
|
||||
|
||||
#[inline]
|
||||
fn visit_variant(
|
||||
&mut self,
|
||||
old_op: &OpTy<'tcx, M::PointerTag>,
|
||||
variant_id: VariantIdx,
|
||||
new_op: &OpTy<'tcx, M::PointerTag>,
|
||||
) -> InterpResult<'tcx> {
|
||||
let name = match old_op.layout.ty.kind() {
|
||||
ty::Adt(adt, _) => PathElem::Variant(adt.variants[variant_id].ident.name),
|
||||
// Generators also have variants
|
||||
ty::Generator(..) => PathElem::GeneratorState(variant_id),
|
||||
_ => bug!("Unexpected type with variant: {:?}", old_op.layout.ty),
|
||||
};
|
||||
self.with_elem(name, move |this| this.visit_value(new_op))
|
||||
}
|
||||
|
||||
#[inline(always)]
|
||||
fn visit_union(
|
||||
&mut self,
|
||||
_op: &OpTy<'tcx, M::PointerTag>,
|
||||
_fields: NonZeroUsize,
|
||||
) -> InterpResult<'tcx> {
|
||||
Ok(())
|
||||
}
|
||||
|
||||
#[inline]
|
||||
fn visit_value(&mut self, op: &OpTy<'tcx, M::PointerTag>) -> InterpResult<'tcx> {
|
||||
trace!("visit_value: {:?}, {:?}", *op, op.layout);
|
||||
|
||||
// Check primitive types -- the leafs of our recursive descend.
|
||||
if self.try_visit_primitive(op)? {
|
||||
return Ok(());
|
||||
}
|
||||
// Sanity check: `builtin_deref` does not know any pointers that are not primitive.
|
||||
assert!(op.layout.ty.builtin_deref(true).is_none());
|
||||
|
||||
// Special check preventing `UnsafeCell` in the inner part of constants
|
||||
if let Some(def) = op.layout.ty.ty_adt_def() {
|
||||
if matches!(self.ctfe_mode, Some(CtfeValidationMode::Const { inner: true, .. }))
|
||||
&& Some(def.did) == self.ecx.tcx.lang_items().unsafe_cell_type()
|
||||
{
|
||||
throw_validation_failure!(self.path, { "`UnsafeCell` in a `const`" });
|
||||
}
|
||||
}
|
||||
|
||||
// Recursively walk the value at its type.
|
||||
self.walk_value(op)?;
|
||||
|
||||
// *After* all of this, check the ABI. We need to check the ABI to handle
|
||||
// types like `NonNull` where the `Scalar` info is more restrictive than what
|
||||
// the fields say (`rustc_layout_scalar_valid_range_start`).
|
||||
// But in most cases, this will just propagate what the fields say,
|
||||
// and then we want the error to point at the field -- so, first recurse,
|
||||
// then check ABI.
|
||||
//
|
||||
// FIXME: We could avoid some redundant checks here. For newtypes wrapping
|
||||
// scalars, we do the same check on every "level" (e.g., first we check
|
||||
// MyNewtype and then the scalar in there).
|
||||
match op.layout.abi {
|
||||
Abi::Uninhabited => {
|
||||
throw_validation_failure!(self.path,
|
||||
{ "a value of uninhabited type {:?}", op.layout.ty }
|
||||
);
|
||||
}
|
||||
Abi::Scalar(ref scalar_layout) => {
|
||||
self.visit_scalar(op, scalar_layout)?;
|
||||
}
|
||||
Abi::ScalarPair { .. } | Abi::Vector { .. } => {
|
||||
// These have fields that we already visited above, so we already checked
|
||||
// all their scalar-level restrictions.
|
||||
// There is also no equivalent to `rustc_layout_scalar_valid_range_start`
|
||||
// that would make skipping them here an issue.
|
||||
}
|
||||
Abi::Aggregate { .. } => {
|
||||
// Nothing to do.
|
||||
}
|
||||
}
|
||||
|
||||
Ok(())
|
||||
}
|
||||
|
||||
fn visit_aggregate(
|
||||
&mut self,
|
||||
op: &OpTy<'tcx, M::PointerTag>,
|
||||
fields: impl Iterator<Item = InterpResult<'tcx, Self::V>>,
|
||||
) -> InterpResult<'tcx> {
|
||||
match op.layout.ty.kind() {
|
||||
ty::Str => {
|
||||
let mplace = op.assert_mem_place(); // strings are never immediate
|
||||
let len = mplace.len(self.ecx)?;
|
||||
try_validation!(
|
||||
self.ecx.memory.read_bytes(mplace.ptr, Size::from_bytes(len)),
|
||||
self.path,
|
||||
err_ub!(InvalidUninitBytes(..)) => { "uninitialized data in `str`" },
|
||||
err_unsup!(ReadPointerAsBytes) => { "a pointer in `str`" },
|
||||
);
|
||||
}
|
||||
ty::Array(tys, ..) | ty::Slice(tys)
|
||||
// This optimization applies for types that can hold arbitrary bytes (such as
|
||||
// integer and floating point types) or for structs or tuples with no fields.
|
||||
// FIXME(wesleywiser) This logic could be extended further to arbitrary structs
|
||||
// or tuples made up of integer/floating point types or inhabited ZSTs with no
|
||||
// padding.
|
||||
if matches!(tys.kind(), ty::Int(..) | ty::Uint(..) | ty::Float(..))
|
||||
=>
|
||||
{
|
||||
// Optimized handling for arrays of integer/float type.
|
||||
|
||||
// Arrays cannot be immediate, slices are never immediate.
|
||||
let mplace = op.assert_mem_place();
|
||||
// This is the length of the array/slice.
|
||||
let len = mplace.len(self.ecx)?;
|
||||
// This is the element type size.
|
||||
let layout = self.ecx.layout_of(tys)?;
|
||||
// This is the size in bytes of the whole array. (This checks for overflow.)
|
||||
let size = layout.size * len;
|
||||
|
||||
// Optimization: we just check the entire range at once.
|
||||
// NOTE: Keep this in sync with the handling of integer and float
|
||||
// types above, in `visit_primitive`.
|
||||
// In run-time mode, we accept pointers in here. This is actually more
|
||||
// permissive than a per-element check would be, e.g., we accept
|
||||
// a &[u8] that contains a pointer even though bytewise checking would
|
||||
// reject it. However, that's good: We don't inherently want
|
||||
// to reject those pointers, we just do not have the machinery to
|
||||
// talk about parts of a pointer.
|
||||
// We also accept uninit, for consistency with the slow path.
|
||||
let alloc = match self.ecx.memory.get(mplace.ptr, size, mplace.align)? {
|
||||
Some(a) => a,
|
||||
None => {
|
||||
// Size 0, nothing more to check.
|
||||
return Ok(());
|
||||
}
|
||||
};
|
||||
|
||||
match alloc.check_bytes(
|
||||
alloc_range(Size::ZERO, size),
|
||||
/*allow_uninit_and_ptr*/ self.ctfe_mode.is_none(),
|
||||
) {
|
||||
// In the happy case, we needn't check anything else.
|
||||
Ok(()) => {}
|
||||
// Some error happened, try to provide a more detailed description.
|
||||
Err(err) => {
|
||||
// For some errors we might be able to provide extra information.
|
||||
// (This custom logic does not fit the `try_validation!` macro.)
|
||||
match err.kind() {
|
||||
err_ub!(InvalidUninitBytes(Some((_alloc_id, access)))) => {
|
||||
// Some byte was uninitialized, determine which
|
||||
// element that byte belongs to so we can
|
||||
// provide an index.
|
||||
let i = usize::try_from(
|
||||
access.uninit_offset.bytes() / layout.size.bytes(),
|
||||
)
|
||||
.unwrap();
|
||||
self.path.push(PathElem::ArrayElem(i));
|
||||
|
||||
throw_validation_failure!(self.path, { "uninitialized bytes" })
|
||||
}
|
||||
err_unsup!(ReadPointerAsBytes) => {
|
||||
throw_validation_failure!(self.path, { "a pointer" } expected { "plain (non-pointer) bytes" })
|
||||
}
|
||||
|
||||
// Propagate upwards (that will also check for unexpected errors).
|
||||
_ => return Err(err),
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
// Fast path for arrays and slices of ZSTs. We only need to check a single ZST element
|
||||
// of an array and not all of them, because there's only a single value of a specific
|
||||
// ZST type, so either validation fails for all elements or none.
|
||||
ty::Array(tys, ..) | ty::Slice(tys) if self.ecx.layout_of(tys)?.is_zst() => {
|
||||
// Validate just the first element (if any).
|
||||
self.walk_aggregate(op, fields.take(1))?
|
||||
}
|
||||
_ => {
|
||||
self.walk_aggregate(op, fields)? // default handler
|
||||
}
|
||||
}
|
||||
Ok(())
|
||||
}
|
||||
}
|
||||
|
||||
impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
|
||||
fn validate_operand_internal(
|
||||
&self,
|
||||
op: &OpTy<'tcx, M::PointerTag>,
|
||||
path: Vec<PathElem>,
|
||||
ref_tracking: Option<&mut RefTracking<MPlaceTy<'tcx, M::PointerTag>, Vec<PathElem>>>,
|
||||
ctfe_mode: Option<CtfeValidationMode>,
|
||||
) -> InterpResult<'tcx> {
|
||||
trace!("validate_operand_internal: {:?}, {:?}", *op, op.layout.ty);
|
||||
|
||||
// Construct a visitor
|
||||
let mut visitor = ValidityVisitor { path, ref_tracking, ctfe_mode, ecx: self };
|
||||
|
||||
// Run it.
|
||||
match visitor.visit_value(&op) {
|
||||
Ok(()) => Ok(()),
|
||||
// Pass through validation failures.
|
||||
Err(err) if matches!(err.kind(), err_ub!(ValidationFailure { .. })) => Err(err),
|
||||
// Also pass through InvalidProgram, those just indicate that we could not
|
||||
// validate and each caller will know best what to do with them.
|
||||
Err(err) if matches!(err.kind(), InterpError::InvalidProgram(_)) => Err(err),
|
||||
// Avoid other errors as those do not show *where* in the value the issue lies.
|
||||
Err(err) => {
|
||||
err.print_backtrace();
|
||||
bug!("Unexpected error during validation: {}", err);
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
/// This function checks the data at `op` to be const-valid.
|
||||
/// `op` is assumed to cover valid memory if it is an indirect operand.
|
||||
/// It will error if the bits at the destination do not match the ones described by the layout.
|
||||
///
|
||||
/// `ref_tracking` is used to record references that we encounter so that they
|
||||
/// can be checked recursively by an outside driving loop.
|
||||
///
|
||||
/// `constant` controls whether this must satisfy the rules for constants:
|
||||
/// - no pointers to statics.
|
||||
/// - no `UnsafeCell` or non-ZST `&mut`.
|
||||
#[inline(always)]
|
||||
pub fn const_validate_operand(
|
||||
&self,
|
||||
op: &OpTy<'tcx, M::PointerTag>,
|
||||
path: Vec<PathElem>,
|
||||
ref_tracking: &mut RefTracking<MPlaceTy<'tcx, M::PointerTag>, Vec<PathElem>>,
|
||||
ctfe_mode: CtfeValidationMode,
|
||||
) -> InterpResult<'tcx> {
|
||||
self.validate_operand_internal(op, path, Some(ref_tracking), Some(ctfe_mode))
|
||||
}
|
||||
|
||||
/// This function checks the data at `op` to be runtime-valid.
|
||||
/// `op` is assumed to cover valid memory if it is an indirect operand.
|
||||
/// It will error if the bits at the destination do not match the ones described by the layout.
|
||||
#[inline(always)]
|
||||
pub fn validate_operand(&self, op: &OpTy<'tcx, M::PointerTag>) -> InterpResult<'tcx> {
|
||||
self.validate_operand_internal(op, vec![], None, None)
|
||||
}
|
||||
}
|
||||
Reference in New Issue
Block a user