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, InterpCx, InterpResult, MPlaceTy, Machine,
24 MemPlaceMeta, OpTy, 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::PointerTag>, 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::Binding(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.variants[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::PointerTag>,
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 = self.ecx.scalar_to_ptr(meta.unwrap_meta());
316 // Direct call to `check_ptr_access_align` checks alignment even on CTFE machines.
318 self.ecx.memory.check_ptr_access_align(
320 3 * self.ecx.tcx.data_layout.pointer_size, // drop, size, align
321 self.ecx.tcx.data_layout.pointer_align.abi,
322 CheckInAllocMsg::InboundsTest, // will anyway be replaced by validity message
325 err_ub!(DanglingIntPointer(..)) |
326 err_ub!(PointerUseAfterFree(..)) =>
327 { "dangling vtable pointer in wide pointer" },
328 err_ub!(AlignmentCheckFailed { .. }) =>
329 { "unaligned vtable pointer in wide pointer" },
330 err_ub!(PointerOutOfBounds { .. }) =>
331 { "too small vtable" },
334 self.ecx.read_drop_type_from_vtable(vtable),
336 err_ub!(DanglingIntPointer(..)) |
337 err_ub!(InvalidFunctionPointer(..)) =>
338 { "invalid drop function pointer in vtable (not pointing to a function)" },
339 err_ub!(InvalidVtableDropFn(..)) =>
340 { "invalid drop function pointer in vtable (function has incompatible signature)" },
343 self.ecx.read_size_and_align_from_vtable(vtable),
345 err_ub!(InvalidVtableSize) =>
346 { "invalid vtable: size is bigger than largest supported object" },
347 err_ub!(InvalidVtableAlignment(msg)) =>
348 { "invalid vtable: alignment {}", msg },
349 err_unsup!(ReadPointerAsBytes) => { "invalid size or align in vtable" },
351 // FIXME: More checks for the vtable.
353 ty::Slice(..) | ty::Str => {
354 let _len = try_validation!(
355 meta.unwrap_meta().to_machine_usize(self.ecx),
357 err_unsup!(ReadPointerAsBytes) => { "non-integer slice length in wide pointer" },
359 // We do not check that `len * elem_size <= isize::MAX`:
360 // that is only required for references, and there it falls out of the
361 // "dereferenceable" check performed by Stacked Borrows.
364 // Unsized, but not wide.
366 _ => bug!("Unexpected unsized type tail: {:?}", tail),
372 /// Check a reference or `Box`.
373 fn check_safe_pointer(
375 value: &OpTy<'tcx, M::PointerTag>,
377 ) -> InterpResult<'tcx> {
378 let value = try_validation!(
379 self.ecx.read_immediate(value),
381 err_unsup!(ReadPointerAsBytes) => { "part of a pointer" } expected { "a proper pointer or integer value" },
383 // Handle wide pointers.
384 // Check metadata early, for better diagnostics
385 let place = try_validation!(
386 self.ecx.ref_to_mplace(&value),
388 err_ub!(InvalidUninitBytes(None)) => { "uninitialized {}", kind },
390 if place.layout.is_unsized() {
391 self.check_wide_ptr_meta(place.meta, place.layout)?;
393 // Make sure this is dereferenceable and all.
394 let size_and_align = try_validation!(
395 self.ecx.size_and_align_of_mplace(&place),
397 err_ub!(InvalidMeta(msg)) => { "invalid {} metadata: {}", kind, msg },
399 let (size, align) = size_and_align
400 // for the purpose of validity, consider foreign types to have
401 // alignment and size determined by the layout (size will be 0,
402 // alignment should take attributes into account).
403 .unwrap_or_else(|| (place.layout.size, place.layout.align.abi));
404 // Direct call to `check_ptr_access_align` checks alignment even on CTFE machines.
406 self.ecx.memory.check_ptr_access_align(
410 CheckInAllocMsg::InboundsTest, // will anyway be replaced by validity message
413 err_ub!(AlignmentCheckFailed { required, has }) =>
415 "an unaligned {} (required {} byte alignment but found {})",
420 err_ub!(DanglingIntPointer(0, _)) =>
421 { "a null {}", kind },
422 err_ub!(DanglingIntPointer(i, _)) =>
423 { "a dangling {} (address 0x{:x} is unallocated)", kind, i },
424 err_ub!(PointerOutOfBounds { .. }) =>
425 { "a dangling {} (going beyond the bounds of its allocation)", kind },
426 // This cannot happen during const-eval (because interning already detects
427 // dangling pointers), but it can happen in Miri.
428 err_ub!(PointerUseAfterFree(..)) =>
429 { "a dangling {} (use-after-free)", kind },
431 // Recursive checking
432 if let Some(ref mut ref_tracking) = self.ref_tracking {
433 // Proceed recursively even for ZST, no reason to skip them!
434 // `!` is a ZST and we want to validate it.
435 // Skip validation entirely for some external statics
436 if let Ok((alloc_id, _offset, _ptr)) = self.ecx.memory.ptr_try_get_alloc(place.ptr) {
438 let alloc_kind = self.ecx.tcx.get_global_alloc(alloc_id);
439 if let Some(GlobalAlloc::Static(did)) = alloc_kind {
440 assert!(!self.ecx.tcx.is_thread_local_static(did));
441 assert!(self.ecx.tcx.is_static(did));
444 Some(CtfeValidationMode::Const { allow_static_ptrs: false, .. })
446 // See const_eval::machine::MemoryExtra::can_access_statics for why
447 // this check is so important.
448 // This check is reachable when the const just referenced the static,
449 // but never read it (so we never entered `before_access_global`).
450 throw_validation_failure!(self.path,
451 { "a {} pointing to a static variable", kind }
454 // We skip checking other statics. These statics must be sound by
455 // themselves, and the only way to get broken statics here is by using
457 // The reasons we don't check other statics is twofold. For one, in all
458 // sound cases, the static was already validated on its own, and second, we
459 // trigger cycle errors if we try to compute the value of the other static
460 // and that static refers back to us.
461 // We might miss const-invalid data,
462 // but things are still sound otherwise (in particular re: consts
463 // referring to statics).
467 let path = &self.path;
468 ref_tracking.track(place, || {
469 // We need to clone the path anyway, make sure it gets created
470 // with enough space for the additional `Deref`.
471 let mut new_path = Vec::with_capacity(path.len() + 1);
472 new_path.clone_from(path);
473 new_path.push(PathElem::Deref);
482 op: &OpTy<'tcx, M::PointerTag>,
483 ) -> InterpResult<'tcx, ScalarMaybeUninit<M::PointerTag>> {
485 self.ecx.read_scalar(op),
487 err_unsup!(ReadPointerAsBytes) => { "(potentially part of) a pointer" } expected { "plain (non-pointer) bytes" },
491 /// Check if this is a value of primitive type, and if yes check the validity of the value
492 /// at that type. Return `true` if the type is indeed primitive.
493 fn try_visit_primitive(
495 value: &OpTy<'tcx, M::PointerTag>,
496 ) -> InterpResult<'tcx, bool> {
497 // Go over all the primitive types
498 let ty = value.layout.ty;
501 let value = self.read_scalar(value)?;
505 err_ub!(InvalidBool(..)) | err_ub!(InvalidUninitBytes(None)) =>
506 { "{}", value } expected { "a boolean" },
511 let value = self.read_scalar(value)?;
515 err_ub!(InvalidChar(..)) | err_ub!(InvalidUninitBytes(None)) =>
516 { "{}", value } expected { "a valid unicode scalar value (in `0..=0x10FFFF` but not in `0xD800..=0xDFFF`)" },
520 ty::Float(_) | ty::Int(_) | ty::Uint(_) => {
521 let value = self.read_scalar(value)?;
522 // NOTE: Keep this in sync with the array optimization for int/float
524 if M::enforce_number_validity(self.ecx) {
525 // Integers/floats in CTFE: Must be scalar bits, pointers are dangerous
526 let is_bits = value.check_init().map_or(false, |v| v.try_to_int().is_ok());
528 throw_validation_failure!(self.path,
529 { "{}", value } expected { "initialized plain (non-pointer) bytes" }
536 // We are conservative with uninit for integers, but try to
537 // actually enforce the strict rules for raw pointers (mostly because
538 // that lets us re-use `ref_to_mplace`).
539 let place = try_validation!(
540 self.ecx.read_immediate(value).and_then(|ref i| self.ecx.ref_to_mplace(i)),
542 err_ub!(InvalidUninitBytes(None)) => { "uninitialized raw pointer" },
543 err_unsup!(ReadPointerAsBytes) => { "part of a pointer" } expected { "a proper pointer or integer value" },
545 if place.layout.is_unsized() {
546 self.check_wide_ptr_meta(place.meta, place.layout)?;
550 ty::Ref(_, ty, mutbl) => {
551 if matches!(self.ctfe_mode, Some(CtfeValidationMode::Const { .. }))
552 && *mutbl == hir::Mutability::Mut
554 // A mutable reference inside a const? That does not seem right (except if it is
556 let layout = self.ecx.layout_of(*ty)?;
557 if !layout.is_zst() {
558 throw_validation_failure!(self.path, { "mutable reference in a `const`" });
561 self.check_safe_pointer(value, "reference")?;
564 ty::Adt(def, ..) if def.is_box() => {
565 self.check_safe_pointer(value, "box")?;
569 let value = try_validation!(
570 self.ecx.read_immediate(value),
572 err_unsup!(ReadPointerAsBytes) => { "part of a pointer" } expected { "a proper pointer or integer value" },
574 // Make sure we print a `ScalarMaybeUninit` (and not an `ImmTy`) in the error
576 let value = value.to_scalar_or_uninit();
577 let _fn = try_validation!(
578 value.check_init().and_then(|ptr| self.ecx.memory.get_fn(self.ecx.scalar_to_ptr(ptr))),
580 err_ub!(DanglingIntPointer(..)) |
581 err_ub!(InvalidFunctionPointer(..)) |
582 err_ub!(InvalidUninitBytes(None)) =>
583 { "{}", value } expected { "a function pointer" },
585 // FIXME: Check if the signature matches
588 ty::Never => throw_validation_failure!(self.path, { "a value of the never type `!`" }),
589 ty::Foreign(..) | ty::FnDef(..) => {
593 // The above should be all the primitive types. The rest is compound, we
594 // check them by visiting their fields/variants.
602 | ty::Generator(..) => Ok(false),
603 // Some types only occur during typechecking, they have no layout.
604 // We should not see them here and we could not check them anyway.
607 | ty::Placeholder(..)
612 | ty::GeneratorWitness(..) => bug!("Encountered invalid type {:?}", ty),
618 op: &OpTy<'tcx, M::PointerTag>,
619 scalar_layout: ScalarAbi,
620 ) -> InterpResult<'tcx> {
621 if scalar_layout.valid_range.is_full_for(op.layout.size) {
625 // At least one value is excluded.
626 let valid_range = scalar_layout.valid_range;
627 let WrappingRange { start, end } = valid_range;
628 let max_value = op.layout.size.unsigned_int_max();
629 assert!(end <= max_value);
630 // Determine the allowed range
631 let value = self.read_scalar(op)?;
632 let value = try_validation!(
635 err_ub!(InvalidUninitBytes(None)) => { "{}", value }
636 expected { "something {}", wrapping_range_format(valid_range, max_value) },
638 let bits = match value.try_to_int() {
640 // So this is a pointer then, and casting to an int failed.
641 // Can only happen during CTFE.
642 let ptr = self.ecx.scalar_to_ptr(value);
643 if start == 1 && end == max_value {
644 // Only null is the niche. So make sure the ptr is NOT null.
645 if self.ecx.memory.ptr_may_be_null(ptr) {
646 throw_validation_failure!(self.path,
647 { "a potentially null pointer" }
649 "something that cannot possibly fail to be {}",
650 wrapping_range_format(valid_range, max_value)
656 // Conservatively, we reject, because the pointer *could* have a bad
658 throw_validation_failure!(self.path,
661 "something that cannot possibly fail to be {}",
662 wrapping_range_format(valid_range, max_value)
667 Ok(int) => int.assert_bits(op.layout.size),
669 // Now compare. This is slightly subtle because this is a special "wrap-around" range.
670 if valid_range.contains(bits) {
673 throw_validation_failure!(self.path,
675 expected { "something {}", wrapping_range_format(valid_range, max_value) }
681 impl<'rt, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> ValueVisitor<'mir, 'tcx, M>
682 for ValidityVisitor<'rt, 'mir, 'tcx, M>
684 type V = OpTy<'tcx, M::PointerTag>;
687 fn ecx(&self) -> &InterpCx<'mir, 'tcx, M> {
691 fn read_discriminant(
693 op: &OpTy<'tcx, M::PointerTag>,
694 ) -> InterpResult<'tcx, VariantIdx> {
695 self.with_elem(PathElem::EnumTag, move |this| {
697 this.ecx.read_discriminant(op),
699 err_ub!(InvalidTag(val)) =>
700 { "{}", val } expected { "a valid enum tag" },
701 err_ub!(InvalidUninitBytes(None)) =>
702 { "uninitialized bytes" } expected { "a valid enum tag" },
703 err_unsup!(ReadPointerAsBytes) =>
704 { "a pointer" } expected { "a valid enum tag" },
713 old_op: &OpTy<'tcx, M::PointerTag>,
715 new_op: &OpTy<'tcx, M::PointerTag>,
716 ) -> InterpResult<'tcx> {
717 let elem = self.aggregate_field_path_elem(old_op.layout, field);
718 self.with_elem(elem, move |this| this.visit_value(new_op))
724 old_op: &OpTy<'tcx, M::PointerTag>,
725 variant_id: VariantIdx,
726 new_op: &OpTy<'tcx, M::PointerTag>,
727 ) -> InterpResult<'tcx> {
728 let name = match old_op.layout.ty.kind() {
729 ty::Adt(adt, _) => PathElem::Variant(adt.variants[variant_id].name),
730 // Generators also have variants
731 ty::Generator(..) => PathElem::GeneratorState(variant_id),
732 _ => bug!("Unexpected type with variant: {:?}", old_op.layout.ty),
734 self.with_elem(name, move |this| this.visit_value(new_op))
740 op: &OpTy<'tcx, M::PointerTag>,
741 _fields: NonZeroUsize,
742 ) -> InterpResult<'tcx> {
743 // Special check preventing `UnsafeCell` inside unions in the inner part of constants.
744 if matches!(self.ctfe_mode, Some(CtfeValidationMode::Const { inner: true, .. })) {
745 if !op.layout.ty.is_freeze(self.ecx.tcx.at(DUMMY_SP), self.ecx.param_env) {
746 throw_validation_failure!(self.path, { "`UnsafeCell` in a `const`" });
753 fn visit_value(&mut self, op: &OpTy<'tcx, M::PointerTag>) -> InterpResult<'tcx> {
754 trace!("visit_value: {:?}, {:?}", *op, op.layout);
756 // Check primitive types -- the leafs of our recursive descend.
757 if self.try_visit_primitive(op)? {
760 // Sanity check: `builtin_deref` does not know any pointers that are not primitive.
761 assert!(op.layout.ty.builtin_deref(true).is_none());
763 // Special check preventing `UnsafeCell` in the inner part of constants
764 if let Some(def) = op.layout.ty.ty_adt_def() {
765 if matches!(self.ctfe_mode, Some(CtfeValidationMode::Const { inner: true, .. }))
766 && Some(def.did) == self.ecx.tcx.lang_items().unsafe_cell_type()
768 throw_validation_failure!(self.path, { "`UnsafeCell` in a `const`" });
772 // Recursively walk the value at its type.
773 self.walk_value(op)?;
775 // *After* all of this, check the ABI. We need to check the ABI to handle
776 // types like `NonNull` where the `Scalar` info is more restrictive than what
777 // the fields say (`rustc_layout_scalar_valid_range_start`).
778 // But in most cases, this will just propagate what the fields say,
779 // and then we want the error to point at the field -- so, first recurse,
782 // FIXME: We could avoid some redundant checks here. For newtypes wrapping
783 // scalars, we do the same check on every "level" (e.g., first we check
784 // MyNewtype and then the scalar in there).
785 match op.layout.abi {
786 Abi::Uninhabited => {
787 throw_validation_failure!(self.path,
788 { "a value of uninhabited type {:?}", op.layout.ty }
791 Abi::Scalar(scalar_layout) => {
792 self.visit_scalar(op, scalar_layout)?;
794 Abi::ScalarPair { .. } | Abi::Vector { .. } => {
795 // These have fields that we already visited above, so we already checked
796 // all their scalar-level restrictions.
797 // There is also no equivalent to `rustc_layout_scalar_valid_range_start`
798 // that would make skipping them here an issue.
800 Abi::Aggregate { .. } => {
810 op: &OpTy<'tcx, M::PointerTag>,
811 fields: impl Iterator<Item = InterpResult<'tcx, Self::V>>,
812 ) -> InterpResult<'tcx> {
813 match op.layout.ty.kind() {
815 let mplace = op.assert_mem_place(); // strings are never immediate
816 let len = mplace.len(self.ecx)?;
818 self.ecx.memory.read_bytes(mplace.ptr, Size::from_bytes(len)),
820 err_ub!(InvalidUninitBytes(..)) => { "uninitialized data in `str`" },
821 err_unsup!(ReadPointerAsBytes) => { "a pointer in `str`" },
824 ty::Array(tys, ..) | ty::Slice(tys)
825 // This optimization applies for types that can hold arbitrary bytes (such as
826 // integer and floating point types) or for structs or tuples with no fields.
827 // FIXME(wesleywiser) This logic could be extended further to arbitrary structs
828 // or tuples made up of integer/floating point types or inhabited ZSTs with no
830 if matches!(tys.kind(), ty::Int(..) | ty::Uint(..) | ty::Float(..))
833 // Optimized handling for arrays of integer/float type.
835 // Arrays cannot be immediate, slices are never immediate.
836 let mplace = op.assert_mem_place();
837 // This is the length of the array/slice.
838 let len = mplace.len(self.ecx)?;
839 // This is the element type size.
840 let layout = self.ecx.layout_of(*tys)?;
841 // This is the size in bytes of the whole array. (This checks for overflow.)
842 let size = layout.size * len;
844 // Optimization: we just check the entire range at once.
845 // NOTE: Keep this in sync with the handling of integer and float
846 // types above, in `visit_primitive`.
847 // In run-time mode, we accept pointers in here. This is actually more
848 // permissive than a per-element check would be, e.g., we accept
849 // a &[u8] that contains a pointer even though bytewise checking would
850 // reject it. However, that's good: We don't inherently want
851 // to reject those pointers, we just do not have the machinery to
852 // talk about parts of a pointer.
853 // We also accept uninit, for consistency with the slow path.
854 let alloc = match self.ecx.memory.get(mplace.ptr, size, mplace.align)? {
857 // Size 0, nothing more to check.
862 let allow_uninit_and_ptr = !M::enforce_number_validity(self.ecx);
863 match alloc.check_bytes(
864 alloc_range(Size::ZERO, size),
865 allow_uninit_and_ptr,
867 // In the happy case, we needn't check anything else.
869 // Some error happened, try to provide a more detailed description.
871 // For some errors we might be able to provide extra information.
872 // (This custom logic does not fit the `try_validation!` macro.)
874 err_ub!(InvalidUninitBytes(Some((_alloc_id, access)))) => {
875 // Some byte was uninitialized, determine which
876 // element that byte belongs to so we can
878 let i = usize::try_from(
879 access.uninit_offset.bytes() / layout.size.bytes(),
882 self.path.push(PathElem::ArrayElem(i));
884 throw_validation_failure!(self.path, { "uninitialized bytes" })
886 err_unsup!(ReadPointerAsBytes) => {
887 throw_validation_failure!(self.path, { "a pointer" } expected { "plain (non-pointer) bytes" })
890 // Propagate upwards (that will also check for unexpected errors).
891 _ => return Err(err),
896 // Fast path for arrays and slices of ZSTs. We only need to check a single ZST element
897 // of an array and not all of them, because there's only a single value of a specific
898 // ZST type, so either validation fails for all elements or none.
899 ty::Array(tys, ..) | ty::Slice(tys) if self.ecx.layout_of(*tys)?.is_zst() => {
900 // Validate just the first element (if any).
901 self.walk_aggregate(op, fields.take(1))?
904 self.walk_aggregate(op, fields)? // default handler
911 impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
912 fn validate_operand_internal(
914 op: &OpTy<'tcx, M::PointerTag>,
916 ref_tracking: Option<&mut RefTracking<MPlaceTy<'tcx, M::PointerTag>, Vec<PathElem>>>,
917 ctfe_mode: Option<CtfeValidationMode>,
918 ) -> InterpResult<'tcx> {
919 trace!("validate_operand_internal: {:?}, {:?}", *op, op.layout.ty);
921 // Construct a visitor
922 let mut visitor = ValidityVisitor { path, ref_tracking, ctfe_mode, ecx: self };
925 match visitor.visit_value(&op) {
927 // Pass through validation failures.
928 Err(err) if matches!(err.kind(), err_ub!(ValidationFailure { .. })) => Err(err),
929 // Also pass through InvalidProgram, those just indicate that we could not
930 // validate and each caller will know best what to do with them.
931 Err(err) if matches!(err.kind(), InterpError::InvalidProgram(_)) => Err(err),
932 // Avoid other errors as those do not show *where* in the value the issue lies.
934 err.print_backtrace();
935 bug!("Unexpected error during validation: {}", err);
940 /// This function checks the data at `op` to be const-valid.
941 /// `op` is assumed to cover valid memory if it is an indirect operand.
942 /// It will error if the bits at the destination do not match the ones described by the layout.
944 /// `ref_tracking` is used to record references that we encounter so that they
945 /// can be checked recursively by an outside driving loop.
947 /// `constant` controls whether this must satisfy the rules for constants:
948 /// - no pointers to statics.
949 /// - no `UnsafeCell` or non-ZST `&mut`.
951 pub fn const_validate_operand(
953 op: &OpTy<'tcx, M::PointerTag>,
955 ref_tracking: &mut RefTracking<MPlaceTy<'tcx, M::PointerTag>, Vec<PathElem>>,
956 ctfe_mode: CtfeValidationMode,
957 ) -> InterpResult<'tcx> {
958 self.validate_operand_internal(op, path, Some(ref_tracking), Some(ctfe_mode))
961 /// This function checks the data at `op` to be runtime-valid.
962 /// `op` is assumed to cover valid memory if it is an indirect operand.
963 /// It will error if the bits at the destination do not match the ones described by the layout.
965 pub fn validate_operand(&self, op: &OpTy<'tcx, M::PointerTag>) -> InterpResult<'tcx> {
966 self.validate_operand_internal(op, vec![], None, None)