1 //! Check the validity invariant of a given value, and tell the user
2 //! where in the value it got violated.
3 //! In const context, this goes even further and tries to approximate const safety.
4 //! That's useful because it means other passes (e.g. promotion) can rely on `const`s
7 use std::convert::TryFrom;
9 use std::num::NonZeroUsize;
11 use rustc_data_structures::fx::FxHashSet;
13 use rustc_middle::mir::interpret::InterpError;
15 use rustc_middle::ty::layout::{LayoutOf, TyAndLayout};
16 use rustc_span::symbol::{sym, Symbol};
17 use rustc_span::DUMMY_SP;
18 use rustc_target::abi::{Abi, Scalar as ScalarAbi, Size, VariantIdx, Variants, WrappingRange};
23 alloc_range, CheckInAllocMsg, GlobalAlloc, Immediate, InterpCx, InterpResult, MPlaceTy,
24 Machine, MemPlaceMeta, OpTy, Scalar, ScalarMaybeUninit, ValueVisitor,
27 macro_rules! throw_validation_failure {
28 ($where:expr, { $( $what_fmt:expr ),+ } $( expected { $( $expected_fmt:expr ),+ } )?) => {{
29 let mut msg = String::new();
30 msg.push_str("encountered ");
31 write!(&mut msg, $($what_fmt),+).unwrap();
33 msg.push_str(", but expected ");
34 write!(&mut msg, $($expected_fmt),+).unwrap();
36 let path = rustc_middle::ty::print::with_no_trimmed_paths!({
38 if !where_.is_empty() {
39 let mut path = String::new();
40 write_path(&mut path, where_);
46 throw_ub!(ValidationFailure { path, msg })
50 /// If $e throws an error matching the pattern, throw a validation failure.
51 /// Other errors are passed back to the caller, unchanged -- and if they reach the root of
52 /// the visitor, we make sure only validation errors and `InvalidProgram` errors are left.
53 /// This lets you use the patterns as a kind of validation list, asserting which errors
54 /// can possibly happen:
57 /// let v = try_validation!(some_fn(), some_path, {
58 /// Foo | Bar | Baz => { "some failure" },
62 /// An additional expected parameter can also be added to the failure message:
65 /// let v = try_validation!(some_fn(), some_path, {
66 /// Foo | Bar | Baz => { "some failure" } expected { "something that wasn't a failure" },
70 /// An additional nicety is that both parameters actually take format args, so you can just write
71 /// the format string in directly:
74 /// let v = try_validation!(some_fn(), some_path, {
75 /// Foo | Bar | Baz => { "{:?}", some_failure } expected { "{}", expected_value },
79 macro_rules! try_validation {
80 ($e:expr, $where:expr,
81 $( $( $p:pat_param )|+ => { $( $what_fmt:expr ),+ } $( expected { $( $expected_fmt:expr ),+ } )? ),+ $(,)?
85 // We catch the error and turn it into a validation failure. We are okay with
86 // allocation here as this can only slow down builds that fail anyway.
87 Err(e) => match e.kind() {
90 throw_validation_failure!(
92 { $( $what_fmt ),+ } $( expected { $( $expected_fmt ),+ } )?
95 #[allow(unreachable_patterns)]
102 /// We want to show a nice path to the invalid field for diagnostics,
103 /// but avoid string operations in the happy case where no error happens.
104 /// So we track a `Vec<PathElem>` where `PathElem` contains all the data we
105 /// need to later print something for the user.
106 #[derive(Copy, Clone, Debug)]
110 GeneratorState(VariantIdx),
120 /// Extra things to check for during validation of CTFE results.
121 pub enum CtfeValidationMode {
122 /// Regular validation, nothing special happening.
124 /// Validation of a `const`.
125 /// `inner` says if this is an inner, indirect allocation (as opposed to the top-level const
126 /// allocation). Being an inner allocation makes a difference because the top-level allocation
127 /// of a `const` is copied for each use, but the inner allocations are implicitly shared.
128 /// `allow_static_ptrs` says if pointers to statics are permitted (which is the case for promoteds in statics).
129 Const { inner: bool, allow_static_ptrs: bool },
132 /// State for tracking recursive validation of references
133 pub struct RefTracking<T, PATH = ()> {
134 pub seen: FxHashSet<T>,
135 pub todo: Vec<(T, PATH)>,
138 impl<T: Copy + Eq + Hash + std::fmt::Debug, PATH: Default> RefTracking<T, PATH> {
139 pub fn empty() -> Self {
140 RefTracking { seen: FxHashSet::default(), todo: vec![] }
142 pub fn new(op: T) -> Self {
143 let mut ref_tracking_for_consts =
144 RefTracking { seen: FxHashSet::default(), todo: vec![(op, PATH::default())] };
145 ref_tracking_for_consts.seen.insert(op);
146 ref_tracking_for_consts
149 pub fn track(&mut self, op: T, path: impl FnOnce() -> PATH) {
150 if self.seen.insert(op) {
151 trace!("Recursing below ptr {:#?}", op);
153 // Remember to come back to this later.
154 self.todo.push((op, path));
160 fn write_path(out: &mut String, path: &[PathElem]) {
161 use self::PathElem::*;
163 for elem in path.iter() {
165 Field(name) => write!(out, ".{}", name),
166 EnumTag => write!(out, ".<enum-tag>"),
167 Variant(name) => write!(out, ".<enum-variant({})>", name),
168 GeneratorTag => write!(out, ".<generator-tag>"),
169 GeneratorState(idx) => write!(out, ".<generator-state({})>", idx.index()),
170 CapturedVar(name) => write!(out, ".<captured-var({})>", name),
171 TupleElem(idx) => write!(out, ".{}", idx),
172 ArrayElem(idx) => write!(out, "[{}]", idx),
173 // `.<deref>` does not match Rust syntax, but it is more readable for long paths -- and
174 // some of the other items here also are not Rust syntax. Actually we can't
175 // even use the usual syntax because we are just showing the projections,
177 Deref => write!(out, ".<deref>"),
178 DynDowncast => write!(out, ".<dyn-downcast>"),
184 // Formats such that a sentence like "expected something {}" to mean
185 // "expected something <in the given range>" makes sense.
186 fn wrapping_range_format(r: WrappingRange, max_hi: u128) -> String {
187 let WrappingRange { start: lo, end: hi } = r;
188 assert!(hi <= max_hi);
190 format!("less or equal to {}, or greater or equal to {}", hi, lo)
192 format!("equal to {}", lo)
194 assert!(hi < max_hi, "should not be printing if the range covers everything");
195 format!("less or equal to {}", hi)
196 } else if hi == max_hi {
197 assert!(lo > 0, "should not be printing if the range covers everything");
198 format!("greater or equal to {}", lo)
200 format!("in the range {:?}", r)
204 struct ValidityVisitor<'rt, 'mir, 'tcx, M: Machine<'mir, 'tcx>> {
205 /// The `path` may be pushed to, but the part that is present when a function
206 /// starts must not be changed! `visit_fields` and `visit_array` rely on
207 /// this stack discipline.
209 ref_tracking: Option<&'rt mut RefTracking<MPlaceTy<'tcx, M::Provenance>, Vec<PathElem>>>,
210 /// `None` indicates this is not validating for CTFE (but for runtime).
211 ctfe_mode: Option<CtfeValidationMode>,
212 ecx: &'rt InterpCx<'mir, 'tcx, M>,
215 impl<'rt, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> ValidityVisitor<'rt, 'mir, 'tcx, M> {
216 fn aggregate_field_path_elem(&mut self, layout: TyAndLayout<'tcx>, field: usize) -> PathElem {
217 // First, check if we are projecting to a variant.
218 match layout.variants {
219 Variants::Multiple { tag_field, .. } => {
220 if tag_field == field {
221 return match layout.ty.kind() {
222 ty::Adt(def, ..) if def.is_enum() => PathElem::EnumTag,
223 ty::Generator(..) => PathElem::GeneratorTag,
224 _ => bug!("non-variant type {:?}", layout.ty),
228 Variants::Single { .. } => {}
231 // Now we know we are projecting to a field, so figure out which one.
232 match layout.ty.kind() {
233 // generators and closures.
234 ty::Closure(def_id, _) | ty::Generator(def_id, _, _) => {
236 // FIXME this should be more descriptive i.e. CapturePlace instead of CapturedVar
237 // https://github.com/rust-lang/project-rfc-2229/issues/46
238 if let Some(local_def_id) = def_id.as_local() {
239 let tables = self.ecx.tcx.typeck(local_def_id);
240 if let Some(captured_place) =
241 tables.closure_min_captures_flattened(*def_id).nth(field)
243 // Sometimes the index is beyond the number of upvars (seen
245 let var_hir_id = captured_place.get_root_variable();
246 let node = self.ecx.tcx.hir().get(var_hir_id);
247 if let hir::Node::Pat(pat) = node {
248 if let hir::PatKind::Binding(_, _, ident, _) = pat.kind {
249 name = Some(ident.name);
255 PathElem::CapturedVar(name.unwrap_or_else(|| {
256 // Fall back to showing the field index.
262 ty::Tuple(_) => PathElem::TupleElem(field),
265 ty::Adt(def, ..) if def.is_enum() => {
266 // we might be projecting *to* a variant, or to a field *in* a variant.
267 match layout.variants {
268 Variants::Single { index } => {
270 PathElem::Field(def.variant(index).fields[field].name)
272 Variants::Multiple { .. } => bug!("we handled variants above"),
277 ty::Adt(def, _) => PathElem::Field(def.non_enum_variant().fields[field].name),
280 ty::Array(..) | ty::Slice(..) => PathElem::ArrayElem(field),
283 ty::Dynamic(..) => PathElem::DynDowncast,
285 // nothing else has an aggregate layout
286 _ => bug!("aggregate_field_path_elem: got non-aggregate type {:?}", layout.ty),
293 f: impl FnOnce(&mut Self) -> InterpResult<'tcx, R>,
294 ) -> InterpResult<'tcx, R> {
295 // Remember the old state
296 let path_len = self.path.len();
297 // Record new element
298 self.path.push(elem);
302 self.path.truncate(path_len);
307 fn check_wide_ptr_meta(
309 meta: MemPlaceMeta<M::Provenance>,
310 pointee: TyAndLayout<'tcx>,
311 ) -> InterpResult<'tcx> {
312 let tail = self.ecx.tcx.struct_tail_erasing_lifetimes(pointee.ty, self.ecx.param_env);
315 let vtable = meta.unwrap_meta().to_pointer(self.ecx)?;
316 // Make sure it is a genuine vtable pointer.
317 let (_ty, _trait) = try_validation!(
318 self.ecx.get_ptr_vtable(vtable),
320 err_ub!(DanglingIntPointer(..)) |
321 err_ub!(InvalidVTablePointer(..)) =>
322 { "{vtable}" } expected { "a vtable pointer" },
324 // FIXME: check if the type/trait match what ty::Dynamic says?
326 ty::Slice(..) | ty::Str => {
327 let _len = try_validation!(
328 meta.unwrap_meta().to_machine_usize(self.ecx),
330 err_unsup!(ReadPointerAsBytes) => { "non-integer slice length in wide pointer" },
332 // We do not check that `len * elem_size <= isize::MAX`:
333 // that is only required for references, and there it falls out of the
334 // "dereferenceable" check performed by Stacked Borrows.
337 // Unsized, but not wide.
339 _ => bug!("Unexpected unsized type tail: {:?}", tail),
345 /// Check a reference or `Box`.
346 fn check_safe_pointer(
348 value: &OpTy<'tcx, M::Provenance>,
350 ) -> InterpResult<'tcx> {
351 let value = try_validation!(
352 self.ecx.read_immediate(value),
354 err_unsup!(ReadPointerAsBytes) => { "part of a pointer" } expected { "a proper pointer or integer value" },
356 // Handle wide pointers.
357 // Check metadata early, for better diagnostics
358 let place = try_validation!(
359 self.ecx.ref_to_mplace(&value),
361 err_ub!(InvalidUninitBytes(None)) => { "uninitialized {}", kind },
363 if place.layout.is_unsized() {
364 self.check_wide_ptr_meta(place.meta, place.layout)?;
366 // Make sure this is dereferenceable and all.
367 let size_and_align = try_validation!(
368 self.ecx.size_and_align_of_mplace(&place),
370 err_ub!(InvalidMeta(msg)) => { "invalid {} metadata: {}", kind, msg },
372 let (size, align) = size_and_align
373 // for the purpose of validity, consider foreign types to have
374 // alignment and size determined by the layout (size will be 0,
375 // alignment should take attributes into account).
376 .unwrap_or_else(|| (place.layout.size, place.layout.align.abi));
377 // Direct call to `check_ptr_access_align` checks alignment even on CTFE machines.
379 self.ecx.check_ptr_access_align(
383 CheckInAllocMsg::InboundsTest, // will anyway be replaced by validity message
386 err_ub!(AlignmentCheckFailed { required, has }) =>
388 "an unaligned {kind} (required {} byte alignment but found {})",
392 err_ub!(DanglingIntPointer(0, _)) =>
394 err_ub!(DanglingIntPointer(i, _)) =>
395 { "a dangling {kind} (address {i:#x} is unallocated)" },
396 err_ub!(PointerOutOfBounds { .. }) =>
397 { "a dangling {kind} (going beyond the bounds of its allocation)" },
398 // This cannot happen during const-eval (because interning already detects
399 // dangling pointers), but it can happen in Miri.
400 err_ub!(PointerUseAfterFree(..)) =>
401 { "a dangling {kind} (use-after-free)" },
403 // Do not allow pointers to uninhabited types.
404 if place.layout.abi.is_uninhabited() {
405 throw_validation_failure!(self.path,
406 { "a {kind} pointing to uninhabited type {}", place.layout.ty }
409 // Recursive checking
410 if let Some(ref mut ref_tracking) = self.ref_tracking {
411 // Proceed recursively even for ZST, no reason to skip them!
412 // `!` is a ZST and we want to validate it.
413 if let Ok((alloc_id, _offset, _prov)) = self.ecx.ptr_try_get_alloc_id(place.ptr) {
414 // Special handling for pointers to statics (irrespective of their type).
415 let alloc_kind = self.ecx.tcx.try_get_global_alloc(alloc_id);
416 if let Some(GlobalAlloc::Static(did)) = alloc_kind {
417 assert!(!self.ecx.tcx.is_thread_local_static(did));
418 assert!(self.ecx.tcx.is_static(did));
421 Some(CtfeValidationMode::Const { allow_static_ptrs: false, .. })
423 // See const_eval::machine::MemoryExtra::can_access_statics for why
424 // this check is so important.
425 // This check is reachable when the const just referenced the static,
426 // but never read it (so we never entered `before_access_global`).
427 throw_validation_failure!(self.path,
428 { "a {} pointing to a static variable", kind }
431 // We skip checking other statics. These statics must be sound by
432 // themselves, and the only way to get broken statics here is by using
434 // The reasons we don't check other statics is twofold. For one, in all
435 // sound cases, the static was already validated on its own, and second, we
436 // trigger cycle errors if we try to compute the value of the other static
437 // and that static refers back to us.
438 // We might miss const-invalid data,
439 // but things are still sound otherwise (in particular re: consts
440 // referring to statics).
444 let path = &self.path;
445 ref_tracking.track(place, || {
446 // We need to clone the path anyway, make sure it gets created
447 // with enough space for the additional `Deref`.
448 let mut new_path = Vec::with_capacity(path.len() + 1);
449 new_path.extend(path);
450 new_path.push(PathElem::Deref);
459 op: &OpTy<'tcx, M::Provenance>,
460 ) -> InterpResult<'tcx, ScalarMaybeUninit<M::Provenance>> {
462 self.ecx.read_scalar(op),
464 err_unsup!(ReadPointerAsBytes) => { "(potentially part of) a pointer" } expected { "plain (non-pointer) bytes" },
468 fn read_immediate_forced(
470 op: &OpTy<'tcx, M::Provenance>,
471 ) -> InterpResult<'tcx, Immediate<M::Provenance>> {
473 self.ecx.read_immediate_raw(op, /*force*/ true),
475 err_unsup!(ReadPointerAsBytes) => { "(potentially part of) a pointer" } expected { "plain (non-pointer) bytes" },
479 /// Check if this is a value of primitive type, and if yes check the validity of the value
480 /// at that type. Return `true` if the type is indeed primitive.
481 fn try_visit_primitive(
483 value: &OpTy<'tcx, M::Provenance>,
484 ) -> InterpResult<'tcx, bool> {
485 // Go over all the primitive types
486 let ty = value.layout.ty;
489 let value = self.read_scalar(value)?;
493 err_ub!(InvalidBool(..)) | err_ub!(InvalidUninitBytes(None)) =>
494 { "{:x}", value } expected { "a boolean" },
499 let value = self.read_scalar(value)?;
503 err_ub!(InvalidChar(..)) | err_ub!(InvalidUninitBytes(None)) =>
504 { "{:x}", value } expected { "a valid unicode scalar value (in `0..=0x10FFFF` but not in `0xD800..=0xDFFF`)" },
508 ty::Float(_) | ty::Int(_) | ty::Uint(_) => {
509 let value = self.read_scalar(value)?;
510 // NOTE: Keep this in sync with the array optimization for int/float
512 if M::enforce_number_init(self.ecx) {
516 err_ub!(InvalidUninitBytes(..)) =>
517 { "{:x}", value } expected { "initialized bytes" }
520 // As a special exception we *do* match on a `Scalar` here, since we truly want
521 // to know its underlying representation (and *not* cast it to an integer).
522 let is_ptr = value.check_init().map_or(false, |v| matches!(v, Scalar::Ptr(..)));
524 throw_validation_failure!(self.path,
525 { "{:x}", value } expected { "plain (non-pointer) bytes" }
531 // We are conservative with uninit for integers, but try to
532 // actually enforce the strict rules for raw pointers (mostly because
533 // that lets us re-use `ref_to_mplace`).
534 let place = try_validation!(
535 self.ecx.read_immediate(value).and_then(|ref i| self.ecx.ref_to_mplace(i)),
537 err_ub!(InvalidUninitBytes(None)) => { "uninitialized raw pointer" },
538 err_unsup!(ReadPointerAsBytes) => { "part of a pointer" } expected { "a proper pointer or integer value" },
540 if place.layout.is_unsized() {
541 self.check_wide_ptr_meta(place.meta, place.layout)?;
545 ty::Ref(_, ty, mutbl) => {
546 if matches!(self.ctfe_mode, Some(CtfeValidationMode::Const { .. }))
547 && *mutbl == hir::Mutability::Mut
549 // A mutable reference inside a const? That does not seem right (except if it is
551 let layout = self.ecx.layout_of(*ty)?;
552 if !layout.is_zst() {
553 throw_validation_failure!(self.path, { "mutable reference in a `const`" });
556 self.check_safe_pointer(value, "reference")?;
560 let value = try_validation!(
561 self.ecx.read_scalar(value).and_then(|v| v.check_init()),
563 err_unsup!(ReadPointerAsBytes) => { "part of a pointer" } expected { "a proper pointer or integer value" },
564 err_ub!(InvalidUninitBytes(None)) => { "uninitialized bytes" } expected { "a proper pointer or integer value" },
567 // If we check references recursively, also check that this points to a function.
568 if let Some(_) = self.ref_tracking {
569 let ptr = value.to_pointer(self.ecx)?;
570 let _fn = try_validation!(
571 self.ecx.get_ptr_fn(ptr),
573 err_ub!(DanglingIntPointer(..)) |
574 err_ub!(InvalidFunctionPointer(..)) =>
575 { "{ptr}" } expected { "a function pointer" },
577 // FIXME: Check if the signature matches
579 // Otherwise (for standalone Miri), we have to still check it to be non-null.
580 if self.ecx.scalar_may_be_null(value)? {
581 throw_validation_failure!(self.path, { "a null function pointer" });
586 ty::Never => throw_validation_failure!(self.path, { "a value of the never type `!`" }),
587 ty::Foreign(..) | ty::FnDef(..) => {
591 // The above should be all the primitive types. The rest is compound, we
592 // check them by visiting their fields/variants.
600 | ty::Generator(..) => Ok(false),
601 // Some types only occur during typechecking, they have no layout.
602 // We should not see them here and we could not check them anyway.
605 | ty::Placeholder(..)
610 | ty::GeneratorWitness(..) => bug!("Encountered invalid type {:?}", ty),
616 scalar: ScalarMaybeUninit<M::Provenance>,
617 scalar_layout: ScalarAbi,
618 ) -> InterpResult<'tcx> {
619 // We check `is_full_range` in a slightly complicated way because *if* we are checking
620 // number validity, then we want to ensure that `Scalar::Initialized` is indeed initialized,
621 // i.e. that we go over the `check_init` below.
622 let size = scalar_layout.size(self.ecx);
623 let is_full_range = match scalar_layout {
624 ScalarAbi::Initialized { .. } => {
625 if M::enforce_number_init(self.ecx) {
626 false // not "full" since uninit is not accepted
628 scalar_layout.is_always_valid(self.ecx)
631 ScalarAbi::Union { .. } => true,
634 // Nothing to check. Cruciall we don't even `read_scalar` until here, since that would
635 // fail for `Union` scalars!
638 // We have something to check: it must at least be initialized.
639 let valid_range = scalar_layout.valid_range(self.ecx);
640 let WrappingRange { start, end } = valid_range;
641 let max_value = size.unsigned_int_max();
642 assert!(end <= max_value);
643 let value = try_validation!(
646 err_ub!(InvalidUninitBytes(None)) => { "{:x}", scalar }
647 expected { "something {}", wrapping_range_format(valid_range, max_value) },
649 let bits = match value.try_to_int() {
650 Ok(int) => int.assert_bits(size),
652 // So this is a pointer then, and casting to an int failed.
653 // Can only happen during CTFE.
654 // We support 2 kinds of ranges here: full range, and excluding zero.
655 if start == 1 && end == max_value {
656 // Only null is the niche. So make sure the ptr is NOT null.
657 if self.ecx.scalar_may_be_null(value)? {
658 throw_validation_failure!(self.path,
659 { "a potentially null pointer" }
661 "something that cannot possibly fail to be {}",
662 wrapping_range_format(valid_range, max_value)
668 } else if scalar_layout.is_always_valid(self.ecx) {
669 // Easy. (This is reachable if `enforce_number_validity` is set.)
672 // Conservatively, we reject, because the pointer *could* have a bad
674 throw_validation_failure!(self.path,
677 "something that cannot possibly fail to be {}",
678 wrapping_range_format(valid_range, max_value)
685 if valid_range.contains(bits) {
688 throw_validation_failure!(self.path,
690 expected { "something {}", wrapping_range_format(valid_range, max_value) }
696 impl<'rt, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> ValueVisitor<'mir, 'tcx, M>
697 for ValidityVisitor<'rt, 'mir, 'tcx, M>
699 type V = OpTy<'tcx, M::Provenance>;
702 fn ecx(&self) -> &InterpCx<'mir, 'tcx, M> {
706 fn read_discriminant(
708 op: &OpTy<'tcx, M::Provenance>,
709 ) -> InterpResult<'tcx, VariantIdx> {
710 self.with_elem(PathElem::EnumTag, move |this| {
712 this.ecx.read_discriminant(op),
714 err_ub!(InvalidTag(val)) =>
715 { "{:x}", val } expected { "a valid enum tag" },
716 err_ub!(InvalidUninitBytes(None)) =>
717 { "uninitialized bytes" } expected { "a valid enum tag" },
718 err_unsup!(ReadPointerAsBytes) =>
719 { "a pointer" } expected { "a valid enum tag" },
728 old_op: &OpTy<'tcx, M::Provenance>,
730 new_op: &OpTy<'tcx, M::Provenance>,
731 ) -> InterpResult<'tcx> {
732 let elem = self.aggregate_field_path_elem(old_op.layout, field);
733 self.with_elem(elem, move |this| this.visit_value(new_op))
739 old_op: &OpTy<'tcx, M::Provenance>,
740 variant_id: VariantIdx,
741 new_op: &OpTy<'tcx, M::Provenance>,
742 ) -> InterpResult<'tcx> {
743 let name = match old_op.layout.ty.kind() {
744 ty::Adt(adt, _) => PathElem::Variant(adt.variant(variant_id).name),
745 // Generators also have variants
746 ty::Generator(..) => PathElem::GeneratorState(variant_id),
747 _ => bug!("Unexpected type with variant: {:?}", old_op.layout.ty),
749 self.with_elem(name, move |this| this.visit_value(new_op))
755 op: &OpTy<'tcx, M::Provenance>,
756 _fields: NonZeroUsize,
757 ) -> InterpResult<'tcx> {
758 // Special check preventing `UnsafeCell` inside unions in the inner part of constants.
759 if matches!(self.ctfe_mode, Some(CtfeValidationMode::Const { inner: true, .. })) {
760 if !op.layout.ty.is_freeze(self.ecx.tcx.at(DUMMY_SP), self.ecx.param_env) {
761 throw_validation_failure!(self.path, { "`UnsafeCell` in a `const`" });
768 fn visit_box(&mut self, op: &OpTy<'tcx, M::Provenance>) -> InterpResult<'tcx> {
769 self.check_safe_pointer(op, "box")?;
774 fn visit_value(&mut self, op: &OpTy<'tcx, M::Provenance>) -> InterpResult<'tcx> {
775 trace!("visit_value: {:?}, {:?}", *op, op.layout);
777 // Check primitive types -- the leaves of our recursive descent.
778 if self.try_visit_primitive(op)? {
782 // Special check preventing `UnsafeCell` in the inner part of constants
783 if let Some(def) = op.layout.ty.ty_adt_def() {
784 if matches!(self.ctfe_mode, Some(CtfeValidationMode::Const { inner: true, .. }))
785 && def.is_unsafe_cell()
787 throw_validation_failure!(self.path, { "`UnsafeCell` in a `const`" });
791 // Recursively walk the value at its type.
792 self.walk_value(op)?;
794 // *After* all of this, check the ABI. We need to check the ABI to handle
795 // types like `NonNull` where the `Scalar` info is more restrictive than what
796 // the fields say (`rustc_layout_scalar_valid_range_start`).
797 // But in most cases, this will just propagate what the fields say,
798 // and then we want the error to point at the field -- so, first recurse,
801 // FIXME: We could avoid some redundant checks here. For newtypes wrapping
802 // scalars, we do the same check on every "level" (e.g., first we check
803 // MyNewtype and then the scalar in there).
804 match op.layout.abi {
805 Abi::Uninhabited => {
806 throw_validation_failure!(self.path,
807 { "a value of uninhabited type {:?}", op.layout.ty }
810 Abi::Scalar(scalar_layout) => {
811 // We use a 'forced' read because we always need a `Immediate` here
812 // and treating "partially uninit" as "fully uninit" is fine for us.
813 let scalar = self.read_immediate_forced(op)?.to_scalar_or_uninit();
814 self.visit_scalar(scalar, scalar_layout)?;
816 Abi::ScalarPair(a_layout, b_layout) => {
817 // There is no `rustc_layout_scalar_valid_range_start` for pairs, so
818 // we would validate these things as we descend into the fields,
819 // but that can miss bugs in layout computation. Layout computation
820 // is subtle due to enums having ScalarPair layout, where one field
821 // is the discriminant.
822 if cfg!(debug_assertions) {
823 // We use a 'forced' read because we always need a `Immediate` here
824 // and treating "partially uninit" as "fully uninit" is fine for us.
825 let (a, b) = self.read_immediate_forced(op)?.to_scalar_or_uninit_pair();
826 self.visit_scalar(a, a_layout)?;
827 self.visit_scalar(b, b_layout)?;
830 Abi::Vector { .. } => {
831 // No checks here, we assume layout computation gets this right.
832 // (This is harder to check since Miri does not represent these as `Immediate`. We
833 // also cannot use field projections since this might be a newtype around a vector.)
835 Abi::Aggregate { .. } => {
845 op: &OpTy<'tcx, M::Provenance>,
846 fields: impl Iterator<Item = InterpResult<'tcx, Self::V>>,
847 ) -> InterpResult<'tcx> {
848 match op.layout.ty.kind() {
850 let mplace = op.assert_mem_place(); // strings are unsized and hence never immediate
851 let len = mplace.len(self.ecx)?;
853 self.ecx.read_bytes_ptr(mplace.ptr, Size::from_bytes(len)),
855 err_ub!(InvalidUninitBytes(..)) => { "uninitialized data in `str`" },
856 err_unsup!(ReadPointerAsBytes) => { "a pointer in `str`" },
859 ty::Array(tys, ..) | ty::Slice(tys)
860 // This optimization applies for types that can hold arbitrary bytes (such as
861 // integer and floating point types) or for structs or tuples with no fields.
862 // FIXME(wesleywiser) This logic could be extended further to arbitrary structs
863 // or tuples made up of integer/floating point types or inhabited ZSTs with no
865 if matches!(tys.kind(), ty::Int(..) | ty::Uint(..) | ty::Float(..))
868 // Optimized handling for arrays of integer/float type.
870 // This is the length of the array/slice.
871 let len = op.len(self.ecx)?;
872 // This is the element type size.
873 let layout = self.ecx.layout_of(*tys)?;
874 // This is the size in bytes of the whole array. (This checks for overflow.)
875 let size = layout.size * len;
876 // If the size is 0, there is nothing to check.
877 // (`size` can only be 0 of `len` is 0, and empty arrays are always valid.)
878 if size == Size::ZERO {
881 // Now that we definitely have a non-ZST array, we know it lives in memory.
882 let mplace = match op.try_as_mplace() {
883 Ok(mplace) => mplace,
884 Err(imm) => match *imm {
886 throw_validation_failure!(self.path, { "uninitialized bytes" }),
887 Immediate::Scalar(..) | Immediate::ScalarPair(..) =>
888 bug!("arrays/slices can never have Scalar/ScalarPair layout"),
892 // Optimization: we just check the entire range at once.
893 // NOTE: Keep this in sync with the handling of integer and float
894 // types above, in `visit_primitive`.
895 // In run-time mode, we accept pointers in here. This is actually more
896 // permissive than a per-element check would be, e.g., we accept
897 // a &[u8] that contains a pointer even though bytewise checking would
898 // reject it. However, that's good: We don't inherently want
899 // to reject those pointers, we just do not have the machinery to
900 // talk about parts of a pointer.
901 // We also accept uninit, for consistency with the slow path.
902 let alloc = self.ecx.get_ptr_alloc(mplace.ptr, size, mplace.align)?.expect("we already excluded size 0");
904 match alloc.check_bytes(
905 alloc_range(Size::ZERO, size),
906 /*allow_uninit*/ !M::enforce_number_init(self.ecx),
909 // In the happy case, we needn't check anything else.
911 // Some error happened, try to provide a more detailed description.
913 // For some errors we might be able to provide extra information.
914 // (This custom logic does not fit the `try_validation!` macro.)
916 err_ub!(InvalidUninitBytes(Some((_alloc_id, access)))) => {
917 // Some byte was uninitialized, determine which
918 // element that byte belongs to so we can
920 let i = usize::try_from(
921 access.uninit.start.bytes() / layout.size.bytes(),
924 self.path.push(PathElem::ArrayElem(i));
926 throw_validation_failure!(self.path, { "uninitialized bytes" })
928 err_unsup!(ReadPointerAsBytes) => {
929 throw_validation_failure!(self.path, { "a pointer" } expected { "plain (non-pointer) bytes" })
932 // Propagate upwards (that will also check for unexpected errors).
933 _ => return Err(err),
938 // Fast path for arrays and slices of ZSTs. We only need to check a single ZST element
939 // of an array and not all of them, because there's only a single value of a specific
940 // ZST type, so either validation fails for all elements or none.
941 ty::Array(tys, ..) | ty::Slice(tys) if self.ecx.layout_of(*tys)?.is_zst() => {
942 // Validate just the first element (if any).
943 self.walk_aggregate(op, fields.take(1))?
946 self.walk_aggregate(op, fields)? // default handler
953 impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
954 fn validate_operand_internal(
956 op: &OpTy<'tcx, M::Provenance>,
958 ref_tracking: Option<&mut RefTracking<MPlaceTy<'tcx, M::Provenance>, Vec<PathElem>>>,
959 ctfe_mode: Option<CtfeValidationMode>,
960 ) -> InterpResult<'tcx> {
961 trace!("validate_operand_internal: {:?}, {:?}", *op, op.layout.ty);
963 // Construct a visitor
964 let mut visitor = ValidityVisitor { path, ref_tracking, ctfe_mode, ecx: self };
967 match visitor.visit_value(&op) {
969 // Pass through validation failures.
970 Err(err) if matches!(err.kind(), err_ub!(ValidationFailure { .. })) => Err(err),
971 // Also pass through InvalidProgram, those just indicate that we could not
972 // validate and each caller will know best what to do with them.
973 Err(err) if matches!(err.kind(), InterpError::InvalidProgram(_)) => Err(err),
974 // Avoid other errors as those do not show *where* in the value the issue lies.
976 err.print_backtrace();
977 bug!("Unexpected error during validation: {}", err);
982 /// This function checks the data at `op` to be const-valid.
983 /// `op` is assumed to cover valid memory if it is an indirect operand.
984 /// It will error if the bits at the destination do not match the ones described by the layout.
986 /// `ref_tracking` is used to record references that we encounter so that they
987 /// can be checked recursively by an outside driving loop.
989 /// `constant` controls whether this must satisfy the rules for constants:
990 /// - no pointers to statics.
991 /// - no `UnsafeCell` or non-ZST `&mut`.
993 pub fn const_validate_operand(
995 op: &OpTy<'tcx, M::Provenance>,
997 ref_tracking: &mut RefTracking<MPlaceTy<'tcx, M::Provenance>, Vec<PathElem>>,
998 ctfe_mode: CtfeValidationMode,
999 ) -> InterpResult<'tcx> {
1000 self.validate_operand_internal(op, path, Some(ref_tracking), Some(ctfe_mode))
1003 /// This function checks the data at `op` to be runtime-valid.
1004 /// `op` is assumed to cover valid memory if it is an indirect operand.
1005 /// It will error if the bits at the destination do not match the ones described by the layout.
1007 pub fn validate_operand(&self, op: &OpTy<'tcx, M::Provenance>) -> InterpResult<'tcx> {
1008 self.validate_operand_internal(op, vec![], None, None)