954 lines
40 KiB
Rust
954 lines
40 KiB
Rust
//! 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::fmt::Write;
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use std::num::NonZeroUsize;
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use either::{Left, Right};
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use rustc_ast::Mutability;
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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::{
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ExpectedKind, InterpError, InvalidMetaKind, PointerKind, ValidationErrorInfo,
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ValidationErrorKind, ValidationErrorKind::*,
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};
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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::{
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Abi, FieldIdx, Scalar as ScalarAbi, Size, VariantIdx, Variants, WrappingRange,
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};
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use std::hash::Hash;
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use super::{
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AllocId, CheckInAllocMsg, GlobalAlloc, ImmTy, Immediate, InterpCx, InterpResult, MPlaceTy,
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Machine, MemPlaceMeta, OpTy, Pointer, Projectable, Scalar, ValueVisitor,
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};
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// for the validation errors
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use super::InterpError::UndefinedBehavior as Ub;
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use super::InterpError::Unsupported as Unsup;
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use super::UndefinedBehaviorInfo::*;
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use super::UnsupportedOpInfo::*;
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macro_rules! throw_validation_failure {
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($where:expr, $kind: expr) => {{
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let where_ = &$where;
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let path = 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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throw_ub!(ValidationError(ValidationErrorInfo { path, kind: $kind }))
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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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/// ```ignore(illustrative)
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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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/// The patterns must be of type `UndefinedBehaviorInfo`.
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/// An additional expected parameter can also be added to the failure message:
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///
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/// ```ignore(illustrative)
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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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/// ```ignore(illustrative)
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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_param )|+ => $kind: 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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$where,
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$kind
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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: Clone + 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.clone(), 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.clone()) {
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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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// FIXME make this translatable as well?
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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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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::Provenance>, 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 captures = self.ecx.tcx.closure_captures(local_def_id);
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if let Some(captured_place) = captures.get(field) {
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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::Pat(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.variant(index).fields[FieldIdx::from_usize(field)].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, _) => {
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PathElem::Field(def.non_enum_variant().fields[FieldIdx::from_usize(field)].name)
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}
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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 read_immediate(
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&self,
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op: &OpTy<'tcx, M::Provenance>,
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expected: ExpectedKind,
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) -> InterpResult<'tcx, ImmTy<'tcx, M::Provenance>> {
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Ok(try_validation!(
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self.ecx.read_immediate(op),
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self.path,
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Ub(InvalidUninitBytes(None)) =>
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Uninit { expected },
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// The `Unsup` cases can only occur during CTFE
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Unsup(ReadPointerAsInt(_)) =>
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PointerAsInt { expected },
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Unsup(ReadPartialPointer(_)) =>
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PartialPointer,
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))
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}
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fn read_scalar(
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&self,
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op: &OpTy<'tcx, M::Provenance>,
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expected: ExpectedKind,
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) -> InterpResult<'tcx, Scalar<M::Provenance>> {
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Ok(self.read_immediate(op, expected)?.to_scalar())
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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::Provenance>,
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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(_, _, ty::Dyn) => {
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let vtable = meta.unwrap_meta().to_pointer(self.ecx)?;
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// Make sure it is a genuine vtable pointer.
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let (_ty, _trait) = try_validation!(
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self.ecx.get_ptr_vtable(vtable),
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self.path,
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Ub(DanglingIntPointer(..) | InvalidVTablePointer(..)) =>
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InvalidVTablePtr { value: format!("{vtable}") }
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);
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// FIXME: check if the type/trait match what ty::Dynamic says?
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}
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ty::Slice(..) | ty::Str => {
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let _len = meta.unwrap_meta().to_target_usize(self.ecx)?;
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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::Provenance>,
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ptr_kind: PointerKind,
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) -> InterpResult<'tcx> {
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// Not using `deref_pointer` since we do the dereferenceable check ourselves below.
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let place = self.ecx.ref_to_mplace(&self.read_immediate(value, ptr_kind.into())?)?;
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// Handle wide pointers.
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// Check metadata early, for better diagnostics
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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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Ub(InvalidMeta(msg)) => match msg {
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InvalidMetaKind::SliceTooBig => InvalidMetaSliceTooLarge { ptr_kind },
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InvalidMetaKind::TooBig => InvalidMetaTooLarge { ptr_kind },
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}
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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.check_ptr_access_align(
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place.ptr,
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size,
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align,
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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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Ub(AlignmentCheckFailed { required, has }) => UnalignedPtr {
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ptr_kind,
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required_bytes: required.bytes(),
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found_bytes: has.bytes()
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},
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Ub(DanglingIntPointer(0, _)) => NullPtr { ptr_kind },
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Ub(DanglingIntPointer(i, _)) => DanglingPtrNoProvenance {
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ptr_kind,
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// FIXME this says "null pointer" when null but we need translate
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pointer: format!("{}", Pointer::<Option<AllocId>>::from_addr_invalid(*i))
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},
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Ub(PointerOutOfBounds { .. }) => DanglingPtrOutOfBounds {
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ptr_kind
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},
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// This cannot happen during const-eval (because interning already detects
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// dangling pointers), but it can happen in Miri.
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Ub(PointerUseAfterFree(..)) => DanglingPtrUseAfterFree {
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ptr_kind,
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},
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);
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// Do not allow pointers to uninhabited types.
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if place.layout.abi.is_uninhabited() {
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let ty = place.layout.ty;
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throw_validation_failure!(self.path, PtrToUninhabited { ptr_kind, ty })
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}
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// Recursive checking
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if let Some(ref_tracking) = self.ref_tracking.as_deref_mut() {
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// Proceed recursively even for ZST, no reason to skip them!
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// `!` is a ZST and we want to validate it.
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if let Ok((alloc_id, _offset, _prov)) = self.ecx.ptr_try_get_alloc_id(place.ptr) {
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// Let's see what kind of memory this points to.
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let alloc_kind = self.ecx.tcx.try_get_global_alloc(alloc_id);
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match alloc_kind {
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Some(GlobalAlloc::Static(did)) => {
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// Special handling for pointers to statics (irrespective of their type).
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assert!(!self.ecx.tcx.is_thread_local_static(did));
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assert!(self.ecx.tcx.is_static(did));
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if matches!(
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self.ctfe_mode,
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Some(CtfeValidationMode::Const { allow_static_ptrs: false, .. })
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) {
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// See const_eval::machine::MemoryExtra::can_access_statics for why
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// this check is so important.
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// This check is reachable when the const just referenced the static,
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// but never read it (so we never entered `before_access_global`).
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throw_validation_failure!(self.path, PtrToStatic { ptr_kind });
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}
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// We skip recursively checking other statics. These statics must be sound by
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// themselves, and the only way to get broken statics here is by using
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// unsafe code.
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// The reasons we don't check other statics is twofold. For one, in all
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// sound cases, the static was already validated on its own, and second, we
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// trigger cycle errors if we try to compute the value of the other static
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// and that static refers back to us.
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// We might miss const-invalid data,
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// but things are still sound otherwise (in particular re: consts
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// referring to statics).
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return Ok(());
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}
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Some(GlobalAlloc::Memory(alloc)) => {
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if alloc.inner().mutability == Mutability::Mut
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&& matches!(self.ctfe_mode, Some(CtfeValidationMode::Const { .. }))
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{
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// This should be unreachable, but if someone manages to copy a pointer
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// out of a `static`, then that pointer might point to mutable memory,
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// and we would catch that here.
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throw_validation_failure!(self.path, PtrToMut { ptr_kind });
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}
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}
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// Nothing to check for these.
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None | Some(GlobalAlloc::Function(..) | GlobalAlloc::VTable(..)) => {}
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}
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}
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let path = &self.path;
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ref_tracking.track(place, || {
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// We need to clone the path anyway, make sure it gets created
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// with enough space for the additional `Deref`.
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let mut new_path = Vec::with_capacity(path.len() + 1);
|
|
new_path.extend(path);
|
|
new_path.push(PathElem::Deref);
|
|
new_path
|
|
});
|
|
}
|
|
Ok(())
|
|
}
|
|
|
|
/// 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.
|
|
///
|
|
/// Note that not all of these have `FieldsShape::Primitive`, e.g. wide references.
|
|
fn try_visit_primitive(
|
|
&mut self,
|
|
value: &OpTy<'tcx, M::Provenance>,
|
|
) -> 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, ExpectedKind::Bool)?;
|
|
try_validation!(
|
|
value.to_bool(),
|
|
self.path,
|
|
Ub(InvalidBool(..)) => ValidationErrorKind::InvalidBool {
|
|
value: format!("{value:x}"),
|
|
}
|
|
);
|
|
Ok(true)
|
|
}
|
|
ty::Char => {
|
|
let value = self.read_scalar(value, ExpectedKind::Char)?;
|
|
try_validation!(
|
|
value.to_char(),
|
|
self.path,
|
|
Ub(InvalidChar(..)) => ValidationErrorKind::InvalidChar {
|
|
value: format!("{value:x}"),
|
|
}
|
|
);
|
|
Ok(true)
|
|
}
|
|
ty::Float(_) | ty::Int(_) | ty::Uint(_) => {
|
|
// NOTE: Keep this in sync with the array optimization for int/float
|
|
// types below!
|
|
self.read_scalar(
|
|
value,
|
|
if matches!(ty.kind(), ty::Float(..)) {
|
|
ExpectedKind::Float
|
|
} else {
|
|
ExpectedKind::Int
|
|
},
|
|
)?;
|
|
Ok(true)
|
|
}
|
|
ty::RawPtr(..) => {
|
|
let place =
|
|
self.ecx.ref_to_mplace(&self.read_immediate(value, ExpectedKind::RawPtr)?)?;
|
|
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 == 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, MutableRefInConst);
|
|
}
|
|
}
|
|
self.check_safe_pointer(value, PointerKind::Ref)?;
|
|
Ok(true)
|
|
}
|
|
ty::FnPtr(_sig) => {
|
|
let value = self.read_scalar(value, ExpectedKind::FnPtr)?;
|
|
|
|
// If we check references recursively, also check that this points to a function.
|
|
if let Some(_) = self.ref_tracking {
|
|
let ptr = value.to_pointer(self.ecx)?;
|
|
let _fn = try_validation!(
|
|
self.ecx.get_ptr_fn(ptr),
|
|
self.path,
|
|
Ub(DanglingIntPointer(..) | InvalidFunctionPointer(..)) =>
|
|
InvalidFnPtr { value: format!("{ptr}") },
|
|
);
|
|
// FIXME: Check if the signature matches
|
|
} else {
|
|
// Otherwise (for standalone Miri), we have to still check it to be non-null.
|
|
if self.ecx.scalar_may_be_null(value)? {
|
|
throw_validation_failure!(self.path, NullFnPtr);
|
|
}
|
|
}
|
|
Ok(true)
|
|
}
|
|
ty::Never => throw_validation_failure!(self.path, NeverVal),
|
|
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::Alias(..)
|
|
| ty::GeneratorWitnessMIR(..)
|
|
| ty::GeneratorWitness(..) => bug!("Encountered invalid type {:?}", ty),
|
|
}
|
|
}
|
|
|
|
fn visit_scalar(
|
|
&mut self,
|
|
scalar: Scalar<M::Provenance>,
|
|
scalar_layout: ScalarAbi,
|
|
) -> InterpResult<'tcx> {
|
|
let size = scalar_layout.size(self.ecx);
|
|
let valid_range = scalar_layout.valid_range(self.ecx);
|
|
let WrappingRange { start, end } = valid_range;
|
|
let max_value = size.unsigned_int_max();
|
|
assert!(end <= max_value);
|
|
let bits = match scalar.try_to_int() {
|
|
Ok(int) => int.assert_bits(size),
|
|
Err(_) => {
|
|
// So this is a pointer then, and casting to an int failed.
|
|
// Can only happen during CTFE.
|
|
// We support 2 kinds of ranges here: full range, and excluding zero.
|
|
if start == 1 && end == max_value {
|
|
// Only null is the niche. So make sure the ptr is NOT null.
|
|
if self.ecx.scalar_may_be_null(scalar)? {
|
|
throw_validation_failure!(
|
|
self.path,
|
|
NullablePtrOutOfRange { range: valid_range, max_value }
|
|
)
|
|
} else {
|
|
return Ok(());
|
|
}
|
|
} else if scalar_layout.is_always_valid(self.ecx) {
|
|
// Easy. (This is reachable if `enforce_number_validity` is set.)
|
|
return Ok(());
|
|
} else {
|
|
// Conservatively, we reject, because the pointer *could* have a bad
|
|
// value.
|
|
throw_validation_failure!(
|
|
self.path,
|
|
PtrOutOfRange { range: valid_range, max_value }
|
|
)
|
|
}
|
|
}
|
|
};
|
|
// Now compare.
|
|
if valid_range.contains(bits) {
|
|
Ok(())
|
|
} else {
|
|
throw_validation_failure!(
|
|
self.path,
|
|
OutOfRange { value: format!("{bits}"), range: valid_range, max_value }
|
|
)
|
|
}
|
|
}
|
|
}
|
|
|
|
impl<'rt, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> ValueVisitor<'mir, 'tcx, M>
|
|
for ValidityVisitor<'rt, 'mir, 'tcx, M>
|
|
{
|
|
type V = OpTy<'tcx, M::Provenance>;
|
|
|
|
#[inline(always)]
|
|
fn ecx(&self) -> &InterpCx<'mir, 'tcx, M> {
|
|
&self.ecx
|
|
}
|
|
|
|
fn read_discriminant(
|
|
&mut self,
|
|
op: &OpTy<'tcx, M::Provenance>,
|
|
) -> InterpResult<'tcx, VariantIdx> {
|
|
self.with_elem(PathElem::EnumTag, move |this| {
|
|
Ok(try_validation!(
|
|
this.ecx.read_discriminant(op),
|
|
this.path,
|
|
Ub(InvalidTag(val)) => InvalidEnumTag {
|
|
value: format!("{val:x}"),
|
|
},
|
|
Ub(UninhabitedEnumVariantRead(_)) => UninhabitedEnumVariant,
|
|
// Uninit / bad provenance are not possible since the field was already previously
|
|
// checked at its integer type.
|
|
))
|
|
})
|
|
}
|
|
|
|
#[inline]
|
|
fn visit_field(
|
|
&mut self,
|
|
old_op: &OpTy<'tcx, M::Provenance>,
|
|
field: usize,
|
|
new_op: &OpTy<'tcx, M::Provenance>,
|
|
) -> 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::Provenance>,
|
|
variant_id: VariantIdx,
|
|
new_op: &OpTy<'tcx, M::Provenance>,
|
|
) -> InterpResult<'tcx> {
|
|
let name = match old_op.layout.ty.kind() {
|
|
ty::Adt(adt, _) => PathElem::Variant(adt.variant(variant_id).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::Provenance>,
|
|
_fields: NonZeroUsize,
|
|
) -> InterpResult<'tcx> {
|
|
// Special check preventing `UnsafeCell` inside unions in the inner part of constants.
|
|
if matches!(self.ctfe_mode, Some(CtfeValidationMode::Const { inner: true, .. })) {
|
|
if !op.layout.ty.is_freeze(*self.ecx.tcx, self.ecx.param_env) {
|
|
throw_validation_failure!(self.path, UnsafeCell);
|
|
}
|
|
}
|
|
Ok(())
|
|
}
|
|
|
|
#[inline]
|
|
fn visit_box(&mut self, op: &OpTy<'tcx, M::Provenance>) -> InterpResult<'tcx> {
|
|
self.check_safe_pointer(op, PointerKind::Box)?;
|
|
Ok(())
|
|
}
|
|
|
|
#[inline]
|
|
fn visit_value(&mut self, op: &OpTy<'tcx, M::Provenance>) -> InterpResult<'tcx> {
|
|
trace!("visit_value: {:?}, {:?}", *op, op.layout);
|
|
|
|
// Check primitive types -- the leaves of our recursive descent.
|
|
if self.try_visit_primitive(op)? {
|
|
return Ok(());
|
|
}
|
|
|
|
// 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, .. }))
|
|
&& def.is_unsafe_cell()
|
|
{
|
|
throw_validation_failure!(self.path, UnsafeCell);
|
|
}
|
|
}
|
|
|
|
// Recursively walk the value at its type. Apply optimizations for some large types.
|
|
match op.layout.ty.kind() {
|
|
ty::Str => {
|
|
let mplace = op.assert_mem_place(); // strings are unsized and hence never immediate
|
|
let len = mplace.len(self.ecx)?;
|
|
try_validation!(
|
|
self.ecx.read_bytes_ptr_strip_provenance(mplace.ptr, Size::from_bytes(len)),
|
|
self.path,
|
|
Ub(InvalidUninitBytes(..)) => Uninit { expected: ExpectedKind::Str },
|
|
Unsup(ReadPointerAsInt(_)) => PointerAsInt { expected: ExpectedKind::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(..))
|
|
=>
|
|
{
|
|
let expected = if tys.is_integral() { ExpectedKind::Int } else { ExpectedKind::Float };
|
|
// Optimized handling for arrays of integer/float type.
|
|
|
|
// This is the length of the array/slice.
|
|
let len = op.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;
|
|
// If the size is 0, there is nothing to check.
|
|
// (`size` can only be 0 of `len` is 0, and empty arrays are always valid.)
|
|
if size == Size::ZERO {
|
|
return Ok(());
|
|
}
|
|
// Now that we definitely have a non-ZST array, we know it lives in memory.
|
|
let mplace = match op.as_mplace_or_imm() {
|
|
Left(mplace) => mplace,
|
|
Right(imm) => match *imm {
|
|
Immediate::Uninit =>
|
|
throw_validation_failure!(self.path, Uninit { expected }),
|
|
Immediate::Scalar(..) | Immediate::ScalarPair(..) =>
|
|
bug!("arrays/slices can never have Scalar/ScalarPair layout"),
|
|
}
|
|
};
|
|
|
|
// 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 = self.ecx.get_ptr_alloc(mplace.ptr, size, mplace.align)?.expect("we already excluded size 0");
|
|
|
|
match alloc.get_bytes_strip_provenance() {
|
|
// 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() {
|
|
Ub(InvalidUninitBytes(Some((_alloc_id, access)))) | Unsup(ReadPointerAsInt(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.bad.start.bytes() / layout.size.bytes(),
|
|
)
|
|
.unwrap();
|
|
self.path.push(PathElem::ArrayElem(i));
|
|
|
|
if matches!(err.kind(), Ub(InvalidUninitBytes(_))) {
|
|
throw_validation_failure!(self.path, Uninit { expected })
|
|
} else {
|
|
throw_validation_failure!(self.path, PointerAsInt { expected })
|
|
}
|
|
}
|
|
|
|
// 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).
|
|
if op.len(self.ecx)? > 0 {
|
|
self.visit_field(op, 0, &self.ecx.project_index(op, 0)?)?;
|
|
}
|
|
}
|
|
_ => {
|
|
self.walk_value(op)?; // default handler
|
|
}
|
|
}
|
|
|
|
// *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 => {
|
|
let ty = op.layout.ty;
|
|
throw_validation_failure!(self.path, UninhabitedVal { ty });
|
|
}
|
|
Abi::Scalar(scalar_layout) => {
|
|
if !scalar_layout.is_uninit_valid() {
|
|
// There is something to check here.
|
|
let scalar = self.read_scalar(op, ExpectedKind::InitScalar)?;
|
|
self.visit_scalar(scalar, scalar_layout)?;
|
|
}
|
|
}
|
|
Abi::ScalarPair(a_layout, b_layout) => {
|
|
// We can only proceed if *both* scalars need to be initialized.
|
|
// FIXME: find a way to also check ScalarPair when one side can be uninit but
|
|
// the other must be init.
|
|
if !a_layout.is_uninit_valid() && !b_layout.is_uninit_valid() {
|
|
let (a, b) =
|
|
self.read_immediate(op, ExpectedKind::InitScalar)?.to_scalar_pair();
|
|
self.visit_scalar(a, a_layout)?;
|
|
self.visit_scalar(b, b_layout)?;
|
|
}
|
|
}
|
|
Abi::Vector { .. } => {
|
|
// No checks here, we assume layout computation gets this right.
|
|
// (This is harder to check since Miri does not represent these as `Immediate`. We
|
|
// also cannot use field projections since this might be a newtype around a vector.)
|
|
}
|
|
Abi::Aggregate { .. } => {
|
|
// Nothing to do.
|
|
}
|
|
}
|
|
|
|
Ok(())
|
|
}
|
|
}
|
|
|
|
impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
|
|
fn validate_operand_internal(
|
|
&self,
|
|
op: &OpTy<'tcx, M::Provenance>,
|
|
path: Vec<PathElem>,
|
|
ref_tracking: Option<&mut RefTracking<MPlaceTy<'tcx, M::Provenance>, 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 and "invalid program" issues.
|
|
Err(err)
|
|
if matches!(
|
|
err.kind(),
|
|
err_ub!(ValidationError { .. }) | InterpError::InvalidProgram(_)
|
|
) =>
|
|
{
|
|
Err(err)
|
|
}
|
|
// Complain about any other kind of error -- those are bad because we'd like to
|
|
// report them in a way that shows *where* in the value the issue lies.
|
|
Err(err) => {
|
|
let (err, backtrace) = err.into_parts();
|
|
backtrace.print_backtrace();
|
|
bug!("Unexpected Undefined Behavior 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::Provenance>,
|
|
path: Vec<PathElem>,
|
|
ref_tracking: &mut RefTracking<MPlaceTy<'tcx, M::Provenance>, 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::Provenance>) -> InterpResult<'tcx> {
|
|
// Note that we *could* actually be in CTFE here with `-Zextra-const-ub-checks`, but it's
|
|
// still correct to not use `ctfe_mode`: that mode is for validation of the final constant
|
|
// value, it rules out things like `UnsafeCell` in awkward places. It also can make checking
|
|
// recurse through references which, for now, we don't want here, either.
|
|
self.validate_operand_internal(op, vec![], None, None)
|
|
}
|
|
}
|