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;
10 use std::ops::RangeInclusive;
12 use rustc_data_structures::fx::FxHashSet;
14 use rustc_middle::mir::interpret::{InterpError, InterpErrorInfo};
16 use rustc_middle::ty::layout::TyAndLayout;
17 use rustc_span::symbol::{sym, Symbol};
18 use rustc_target::abi::{Abi, LayoutOf, Scalar, VariantIdx, Variants};
23 CheckInAllocMsg, GlobalAlloc, InterpCx, InterpResult, MPlaceTy, Machine, MemPlaceMeta, OpTy,
27 macro_rules! throw_validation_failure {
28 ($what:expr, $where:expr $(, $expected:expr )?) => {{
29 let mut msg = format!("encountered {}", $what);
31 if !where_.is_empty() {
33 write_path(&mut msg, where_);
35 $( write!(&mut msg, ", but expected {}", $expected).unwrap(); )?
36 throw_ub!(ValidationFailure(msg))
40 /// Returns a validation failure for any Err value of $e.
41 // FIXME: Replace all usages of try_validation! with try_validation_pat!.
42 macro_rules! try_validation {
43 ($e:expr, $what:expr, $where:expr $(, $expected:expr )?) => {{
44 try_validation_pat!($e, $where, {
45 _ => { "{}", $what } $( expected { "{}", $expected } )?,
49 /// Like try_validation, but will throw a validation error if any of the patterns in $p are
50 /// matched. Other errors are passed back to the caller, unchanged. This lets you use the patterns
51 /// as a kind of validation blacklist:
54 /// let v = try_validation_pat!(some_fn(), some_path, {
55 /// Foo | Bar | Baz => { "some failure" },
57 /// // Failures that match $p are thrown up as validation errors, but other errors are passed back
61 /// An additional expected parameter can also be added to the failure message:
64 /// let v = try_validation_pat!(some_fn(), some_path, {
65 /// Foo | Bar | Baz => { "some failure" } expected { "something that wasn't a failure" },
69 /// An additional nicety is that both parameters actually take format args, so you can just write
70 /// the format string in directly:
73 /// let v = try_validation_pat!(some_fn(), some_path, {
74 /// Foo | Bar | Baz => { "{:?}", some_failure } expected { "{}", expected_value },
78 macro_rules! try_validation_pat {
79 ($e:expr, $where:expr, { $( $p:pat )|+ =>
80 { $( $what_fmt:expr ),+ } $( expected { $( $expected_fmt:expr ),+ } )? $( , )?}) => {{
83 // We catch the error and turn it into a validation failure. We are okay with
84 // allocation here as this can only slow down builds that fail anyway.
85 $( Err(InterpErrorInfo { kind: $p, .. }) )|+ =>
86 throw_validation_failure!(
87 format_args!($( $what_fmt ),+),
89 $(, format_args!($( $expected_fmt ),+))?
91 #[allow(unreachable_patterns)]
92 Err(e) => Err::<!, _>(e)?,
97 /// We want to show a nice path to the invalid field for diagnostics,
98 /// but avoid string operations in the happy case where no error happens.
99 /// So we track a `Vec<PathElem>` where `PathElem` contains all the data we
100 /// need to later print something for the user.
101 #[derive(Copy, Clone, Debug)]
105 GeneratorState(VariantIdx),
115 /// State for tracking recursive validation of references
116 pub struct RefTracking<T, PATH = ()> {
117 pub seen: FxHashSet<T>,
118 pub todo: Vec<(T, PATH)>,
121 impl<T: Copy + Eq + Hash + std::fmt::Debug, PATH: Default> RefTracking<T, PATH> {
122 pub fn empty() -> Self {
123 RefTracking { seen: FxHashSet::default(), todo: vec![] }
125 pub fn new(op: T) -> Self {
126 let mut ref_tracking_for_consts =
127 RefTracking { seen: FxHashSet::default(), todo: vec![(op, PATH::default())] };
128 ref_tracking_for_consts.seen.insert(op);
129 ref_tracking_for_consts
132 pub fn track(&mut self, op: T, path: impl FnOnce() -> PATH) {
133 if self.seen.insert(op) {
134 trace!("Recursing below ptr {:#?}", op);
136 // Remember to come back to this later.
137 self.todo.push((op, path));
143 fn write_path(out: &mut String, path: &Vec<PathElem>) {
144 use self::PathElem::*;
146 for elem in path.iter() {
148 Field(name) => write!(out, ".{}", name),
149 EnumTag => write!(out, ".<enum-tag>"),
150 Variant(name) => write!(out, ".<enum-variant({})>", name),
151 GeneratorTag => write!(out, ".<generator-tag>"),
152 GeneratorState(idx) => write!(out, ".<generator-state({})>", idx.index()),
153 CapturedVar(name) => write!(out, ".<captured-var({})>", name),
154 TupleElem(idx) => write!(out, ".{}", idx),
155 ArrayElem(idx) => write!(out, "[{}]", idx),
156 // `.<deref>` does not match Rust syntax, but it is more readable for long paths -- and
157 // some of the other items here also are not Rust syntax. Actually we can't
158 // even use the usual syntax because we are just showing the projections,
160 Deref => write!(out, ".<deref>"),
161 DynDowncast => write!(out, ".<dyn-downcast>"),
167 // Test if a range that wraps at overflow contains `test`
168 fn wrapping_range_contains(r: &RangeInclusive<u128>, test: u128) -> bool {
169 let (lo, hi) = r.clone().into_inner();
172 (..=hi).contains(&test) || (lo..).contains(&test)
179 // Formats such that a sentence like "expected something {}" to mean
180 // "expected something <in the given range>" makes sense.
181 fn wrapping_range_format(r: &RangeInclusive<u128>, max_hi: u128) -> String {
182 let (lo, hi) = r.clone().into_inner();
183 assert!(hi <= max_hi);
185 format!("less or equal to {}, or greater or equal to {}", hi, lo)
187 format!("equal to {}", lo)
189 assert!(hi < max_hi, "should not be printing if the range covers everything");
190 format!("less or equal to {}", hi)
191 } else if hi == max_hi {
192 assert!(lo > 0, "should not be printing if the range covers everything");
193 format!("greater or equal to {}", lo)
195 format!("in the range {:?}", r)
199 struct ValidityVisitor<'rt, 'mir, 'tcx, M: Machine<'mir, 'tcx>> {
200 /// The `path` may be pushed to, but the part that is present when a function
201 /// starts must not be changed! `visit_fields` and `visit_array` rely on
202 /// this stack discipline.
204 ref_tracking_for_consts:
205 Option<&'rt mut RefTracking<MPlaceTy<'tcx, M::PointerTag>, Vec<PathElem>>>,
206 may_ref_to_static: bool,
207 ecx: &'rt InterpCx<'mir, 'tcx, M>,
210 impl<'rt, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> ValidityVisitor<'rt, 'mir, 'tcx, M> {
211 fn aggregate_field_path_elem(&mut self, layout: TyAndLayout<'tcx>, field: usize) -> PathElem {
212 // First, check if we are projecting to a variant.
213 match layout.variants {
214 Variants::Multiple { discr_index, .. } => {
215 if discr_index == field {
216 return match layout.ty.kind {
217 ty::Adt(def, ..) if def.is_enum() => PathElem::EnumTag,
218 ty::Generator(..) => PathElem::GeneratorTag,
219 _ => bug!("non-variant type {:?}", layout.ty),
223 Variants::Single { .. } => {}
226 // Now we know we are projecting to a field, so figure out which one.
227 match layout.ty.kind {
228 // generators and closures.
229 ty::Closure(def_id, _) | ty::Generator(def_id, _, _) => {
231 if let Some(def_id) = def_id.as_local() {
232 let tables = self.ecx.tcx.typeck_tables_of(def_id);
233 if let Some(upvars) = tables.upvar_list.get(&def_id.to_def_id()) {
234 // Sometimes the index is beyond the number of upvars (seen
236 if let Some((&var_hir_id, _)) = upvars.get_index(field) {
237 let node = self.ecx.tcx.hir().get(var_hir_id);
238 if let hir::Node::Binding(pat) = node {
239 if let hir::PatKind::Binding(_, _, ident, _) = pat.kind {
240 name = Some(ident.name);
247 PathElem::CapturedVar(name.unwrap_or_else(|| {
248 // Fall back to showing the field index.
254 ty::Tuple(_) => PathElem::TupleElem(field),
257 ty::Adt(def, ..) if def.is_enum() => {
258 // we might be projecting *to* a variant, or to a field *in* a variant.
259 match layout.variants {
260 Variants::Single { index } => {
262 PathElem::Field(def.variants[index].fields[field].ident.name)
264 Variants::Multiple { .. } => bug!("we handled variants above"),
269 ty::Adt(def, _) => PathElem::Field(def.non_enum_variant().fields[field].ident.name),
272 ty::Array(..) | ty::Slice(..) => PathElem::ArrayElem(field),
275 ty::Dynamic(..) => PathElem::DynDowncast,
277 // nothing else has an aggregate layout
278 _ => bug!("aggregate_field_path_elem: got non-aggregate type {:?}", layout.ty),
284 new_op: OpTy<'tcx, M::PointerTag>,
286 ) -> InterpResult<'tcx> {
287 // Remember the old state
288 let path_len = self.path.len();
290 self.path.push(elem);
291 self.visit_value(new_op)?;
293 self.path.truncate(path_len);
297 fn check_wide_ptr_meta(
299 meta: MemPlaceMeta<M::PointerTag>,
300 pointee: TyAndLayout<'tcx>,
301 ) -> InterpResult<'tcx> {
302 let tail = self.ecx.tcx.struct_tail_erasing_lifetimes(pointee.ty, self.ecx.param_env);
305 let vtable = meta.unwrap_meta();
307 self.ecx.memory.check_ptr_access(
309 3 * self.ecx.tcx.data_layout.pointer_size, // drop, size, align
310 self.ecx.tcx.data_layout.pointer_align.abi,
312 "dangling or unaligned vtable pointer in wide pointer or too small vtable",
316 self.ecx.read_drop_type_from_vtable(vtable),
317 "invalid drop fn in vtable",
321 self.ecx.read_size_and_align_from_vtable(vtable),
322 "invalid size or align in vtable",
325 // FIXME: More checks for the vtable.
327 ty::Slice(..) | ty::Str => {
328 let _len = try_validation!(
329 meta.unwrap_meta().to_machine_usize(self.ecx),
330 "non-integer slice length in wide pointer",
333 // We do not check that `len * elem_size <= isize::MAX`:
334 // that is only required for references, and there it falls out of the
335 // "dereferenceable" check performed by Stacked Borrows.
338 // Unsized, but not wide.
340 _ => bug!("Unexpected unsized type tail: {:?}", tail),
346 /// Check a reference or `Box`.
347 fn check_safe_pointer(
349 value: OpTy<'tcx, M::PointerTag>,
351 ) -> InterpResult<'tcx> {
352 let value = self.ecx.read_immediate(value)?;
353 // Handle wide pointers.
354 // Check metadata early, for better diagnostics
355 let place = try_validation!(
356 self.ecx.ref_to_mplace(value),
357 format_args!("uninitialized {}", kind),
360 if place.layout.is_unsized() {
361 self.check_wide_ptr_meta(place.meta, place.layout)?;
363 // Make sure this is dereferenceable and all.
364 let size_and_align = match self.ecx.size_and_align_of(place.meta, place.layout) {
366 Err(err) => match err.kind {
367 err_ub!(InvalidMeta(msg)) => throw_validation_failure!(
368 format_args!("invalid {} metadata: {}", kind, msg),
371 _ => bug!("unexpected error during ptr size_and_align_of: {}", err),
374 let (size, align) = size_and_align
375 // for the purpose of validity, consider foreign types to have
376 // alignment and size determined by the layout (size will be 0,
377 // alignment should take attributes into account).
378 .unwrap_or_else(|| (place.layout.size, place.layout.align.abi));
379 let ptr: Option<_> = match self.ecx.memory.check_ptr_access_align(
383 CheckInAllocMsg::InboundsTest,
388 "{:?} did not pass access check for size {:?}, align {:?}",
389 place.ptr, size, align
392 err_ub!(DanglingIntPointer(0, _)) => {
393 throw_validation_failure!(format_args!("a NULL {}", kind), self.path)
395 err_ub!(DanglingIntPointer(i, _)) => throw_validation_failure!(
396 format_args!("a {} to unallocated address {}", kind, i),
399 err_ub!(AlignmentCheckFailed { required, has }) => throw_validation_failure!(
401 "an unaligned {} (required {} byte alignment but found {})",
408 err_unsup!(ReadBytesAsPointer) => throw_validation_failure!(
409 format_args!("a dangling {} (created from integer)", kind),
412 err_ub!(PointerOutOfBounds { .. }) => throw_validation_failure!(
414 "a dangling {} (going beyond the bounds of its allocation)",
419 // This cannot happen during const-eval (because interning already detects
420 // dangling pointers), but it can happen in Miri.
421 err_ub!(PointerUseAfterFree(_)) => throw_validation_failure!(
422 format_args!("a dangling {} (use-after-free)", kind),
425 _ => bug!("Unexpected error during ptr inbounds test: {}", err),
429 // Recursive checking
430 if let Some(ref mut ref_tracking) = self.ref_tracking_for_consts {
431 if let Some(ptr) = ptr {
433 // Skip validation entirely for some external statics
434 let alloc_kind = self.ecx.tcx.alloc_map.lock().get(ptr.alloc_id);
435 if let Some(GlobalAlloc::Static(did)) = alloc_kind {
436 // See const_eval::machine::MemoryExtra::can_access_statics for why
437 // this check is so important.
438 // This check is reachable when the const just referenced the static,
439 // but never read it (so we never entered `before_access_global`).
440 // We also need to do it here instead of going on to avoid running
441 // into the `before_access_global` check during validation.
442 if !self.may_ref_to_static && self.ecx.tcx.is_static(did) {
443 throw_validation_failure!(
444 format_args!("a {} pointing to a static variable", kind),
448 // `extern static` cannot be validated as they have no body.
449 // FIXME: Statics from other crates are also skipped.
450 // They might be checked at a different type, but for now we
451 // want to avoid recursing too deeply. We might miss const-invalid data,
452 // but things are still sound otherwise (in particular re: consts
453 // referring to statics).
454 if !did.is_local() || self.ecx.tcx.is_foreign_item(did) {
459 // Proceed recursively even for ZST, no reason to skip them!
460 // `!` is a ZST and we want to validate it.
461 // Normalize before handing `place` to tracking because that will
462 // check for duplicates.
463 let place = if size.bytes() > 0 {
464 self.ecx.force_mplace_ptr(place).expect("we already bounds-checked")
468 let path = &self.path;
469 ref_tracking.track(place, || {
470 // We need to clone the path anyway, make sure it gets created
471 // with enough space for the additional `Deref`.
472 let mut new_path = Vec::with_capacity(path.len() + 1);
473 new_path.clone_from(path);
474 new_path.push(PathElem::Deref);
481 /// Check if this is a value of primitive type, and if yes check the validity of the value
482 /// at that type. Return `true` if the type is indeed primitive.
483 fn try_visit_primitive(
485 value: OpTy<'tcx, M::PointerTag>,
486 ) -> InterpResult<'tcx, bool> {
487 // Go over all the primitive types
488 let ty = value.layout.ty;
491 let value = self.ecx.read_scalar(value)?;
492 try_validation!(value.to_bool(), value, self.path, "a boolean");
496 let value = self.ecx.read_scalar(value)?;
497 try_validation!(value.to_char(), value, self.path, "a valid unicode codepoint");
500 ty::Float(_) | ty::Int(_) | ty::Uint(_) => {
501 let value = self.ecx.read_scalar(value)?;
502 // NOTE: Keep this in sync with the array optimization for int/float
504 if self.ref_tracking_for_consts.is_some() {
505 // Integers/floats in CTFE: Must be scalar bits, pointers are dangerous
506 let is_bits = value.not_undef().map_or(false, |v| v.is_bits());
508 throw_validation_failure!(
511 "initialized plain (non-pointer) bytes"
515 // At run-time, for now, we accept *anything* for these types, including
516 // undef. We should fix that, but let's start low.
521 // We are conservative with undef for integers, but try to
522 // actually enforce the strict rules for raw pointers (mostly because
523 // that lets us re-use `ref_to_mplace`).
524 let place = try_validation_pat!(self.ecx.ref_to_mplace(self.ecx.read_immediate(value)?), self.path, {
525 err_ub!(InvalidUndefBytes(..)) => { "uninitialized raw pointer" },
527 if place.layout.is_unsized() {
528 self.check_wide_ptr_meta(place.meta, place.layout)?;
533 self.check_safe_pointer(value, "reference")?;
536 ty::Adt(def, ..) if def.is_box() => {
537 self.check_safe_pointer(value, "box")?;
541 let value = self.ecx.read_scalar(value)?;
542 let _fn = try_validation!(
543 value.not_undef().and_then(|ptr| self.ecx.memory.get_fn(ptr)),
548 // FIXME: Check if the signature matches
551 ty::Never => throw_validation_failure!("a value of the never type `!`", self.path),
552 ty::Foreign(..) | ty::FnDef(..) => {
556 // The above should be all the (inhabited) primitive types. The rest is compound, we
557 // check them by visiting their fields/variants.
558 // (`Str` UTF-8 check happens in `visit_aggregate`, too.)
566 | ty::Generator(..) => Ok(false),
567 // Some types only occur during typechecking, they have no layout.
568 // We should not see them here and we could not check them anyway.
571 | ty::Placeholder(..)
575 | ty::UnnormalizedProjection(..)
577 | ty::GeneratorWitness(..) => bug!("Encountered invalid type {:?}", ty),
583 op: OpTy<'tcx, M::PointerTag>,
584 scalar_layout: &Scalar,
585 ) -> InterpResult<'tcx> {
586 let value = self.ecx.read_scalar(op)?;
587 let valid_range = &scalar_layout.valid_range;
588 let (lo, hi) = valid_range.clone().into_inner();
589 // Determine the allowed range
590 // `max_hi` is as big as the size fits
591 let max_hi = u128::MAX >> (128 - op.layout.size.bits());
592 assert!(hi <= max_hi);
593 // We could also write `(hi + 1) % (max_hi + 1) == lo` but `max_hi + 1` overflows for `u128`
594 if (lo == 0 && hi == max_hi) || (hi + 1 == lo) {
598 // At least one value is excluded. Get the bits.
599 let value = try_validation!(
603 format_args!("something {}", wrapping_range_format(valid_range, max_hi),)
605 let bits = match value.to_bits_or_ptr(op.layout.size, self.ecx) {
607 if lo == 1 && hi == max_hi {
608 // Only NULL is the niche. So make sure the ptr is NOT NULL.
609 if self.ecx.memory.ptr_may_be_null(ptr) {
610 throw_validation_failure!(
611 "a potentially NULL pointer",
614 "something that cannot possibly fail to be {}",
615 wrapping_range_format(valid_range, max_hi)
621 // Conservatively, we reject, because the pointer *could* have a bad
623 throw_validation_failure!(
627 "something that cannot possibly fail to be {}",
628 wrapping_range_format(valid_range, max_hi)
635 // Now compare. This is slightly subtle because this is a special "wrap-around" range.
636 if wrapping_range_contains(&valid_range, bits) {
639 throw_validation_failure!(
642 format_args!("something {}", wrapping_range_format(valid_range, max_hi))
648 impl<'rt, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> ValueVisitor<'mir, 'tcx, M>
649 for ValidityVisitor<'rt, 'mir, 'tcx, M>
651 type V = OpTy<'tcx, M::PointerTag>;
654 fn ecx(&self) -> &InterpCx<'mir, 'tcx, M> {
661 old_op: OpTy<'tcx, M::PointerTag>,
663 new_op: OpTy<'tcx, M::PointerTag>,
664 ) -> InterpResult<'tcx> {
665 let elem = self.aggregate_field_path_elem(old_op.layout, field);
666 self.visit_elem(new_op, elem)
672 old_op: OpTy<'tcx, M::PointerTag>,
673 variant_id: VariantIdx,
674 new_op: OpTy<'tcx, M::PointerTag>,
675 ) -> InterpResult<'tcx> {
676 let name = match old_op.layout.ty.kind {
677 ty::Adt(adt, _) => PathElem::Variant(adt.variants[variant_id].ident.name),
678 // Generators also have variants
679 ty::Generator(..) => PathElem::GeneratorState(variant_id),
680 _ => bug!("Unexpected type with variant: {:?}", old_op.layout.ty),
682 self.visit_elem(new_op, name)
688 _op: OpTy<'tcx, M::PointerTag>,
689 _fields: NonZeroUsize,
690 ) -> InterpResult<'tcx> {
695 fn visit_value(&mut self, op: OpTy<'tcx, M::PointerTag>) -> InterpResult<'tcx> {
696 trace!("visit_value: {:?}, {:?}", *op, op.layout);
698 // Check primitive types -- the leafs of our recursive descend.
699 if self.try_visit_primitive(op)? {
702 // Sanity check: `builtin_deref` does not know any pointers that are not primitive.
703 assert!(op.layout.ty.builtin_deref(true).is_none());
705 // Recursively walk the type. Translate some possible errors to something nicer.
706 match self.walk_value(op) {
708 Err(err) => match err.kind {
709 err_ub!(InvalidDiscriminant(val)) => {
710 throw_validation_failure!(val, self.path, "a valid enum discriminant")
712 err_unsup!(ReadPointerAsBytes) => {
713 throw_validation_failure!("a pointer", self.path, "plain (non-pointer) bytes")
715 // Propagate upwards (that will also check for unexpected errors).
716 _ => return Err(err),
720 // *After* all of this, check the ABI. We need to check the ABI to handle
721 // types like `NonNull` where the `Scalar` info is more restrictive than what
722 // the fields say (`rustc_layout_scalar_valid_range_start`).
723 // But in most cases, this will just propagate what the fields say,
724 // and then we want the error to point at the field -- so, first recurse,
727 // FIXME: We could avoid some redundant checks here. For newtypes wrapping
728 // scalars, we do the same check on every "level" (e.g., first we check
729 // MyNewtype and then the scalar in there).
730 match op.layout.abi {
731 Abi::Uninhabited => {
732 throw_validation_failure!(
733 format_args!("a value of uninhabited type {:?}", op.layout.ty),
737 Abi::Scalar(ref scalar_layout) => {
738 self.visit_scalar(op, scalar_layout)?;
740 Abi::ScalarPair { .. } | Abi::Vector { .. } => {
741 // These have fields that we already visited above, so we already checked
742 // all their scalar-level restrictions.
743 // There is also no equivalent to `rustc_layout_scalar_valid_range_start`
744 // that would make skipping them here an issue.
746 Abi::Aggregate { .. } => {
756 op: OpTy<'tcx, M::PointerTag>,
757 fields: impl Iterator<Item = InterpResult<'tcx, Self::V>>,
758 ) -> InterpResult<'tcx> {
759 match op.layout.ty.kind {
761 let mplace = op.assert_mem_place(self.ecx); // strings are never immediate
763 self.ecx.read_str(mplace),
764 "uninitialized or non-UTF-8 data in str",
768 ty::Array(tys, ..) | ty::Slice(tys)
770 // This optimization applies for types that can hold arbitrary bytes (such as
771 // integer and floating point types) or for structs or tuples with no fields.
772 // FIXME(wesleywiser) This logic could be extended further to arbitrary structs
773 // or tuples made up of integer/floating point types or inhabited ZSTs with no
776 ty::Int(..) | ty::Uint(..) | ty::Float(..) => true,
781 // Optimized handling for arrays of integer/float type.
783 // Arrays cannot be immediate, slices are never immediate.
784 let mplace = op.assert_mem_place(self.ecx);
785 // This is the length of the array/slice.
786 let len = mplace.len(self.ecx)?;
787 // Zero length slices have nothing to be checked.
791 // This is the element type size.
792 let layout = self.ecx.layout_of(tys)?;
793 // This is the size in bytes of the whole array. (This checks for overflow.)
794 let size = layout.size * len;
795 // Size is not 0, get a pointer.
796 let ptr = self.ecx.force_ptr(mplace.ptr)?;
798 // Optimization: we just check the entire range at once.
799 // NOTE: Keep this in sync with the handling of integer and float
800 // types above, in `visit_primitive`.
801 // In run-time mode, we accept pointers in here. This is actually more
802 // permissive than a per-element check would be, e.g., we accept
803 // an &[u8] that contains a pointer even though bytewise checking would
804 // reject it. However, that's good: We don't inherently want
805 // to reject those pointers, we just do not have the machinery to
806 // talk about parts of a pointer.
807 // We also accept undef, for consistency with the slow path.
808 match self.ecx.memory.get_raw(ptr.alloc_id)?.check_bytes(
812 /*allow_ptr_and_undef*/ self.ref_tracking_for_consts.is_none(),
814 // In the happy case, we needn't check anything else.
816 // Some error happened, try to provide a more detailed description.
818 // For some errors we might be able to provide extra information
820 err_ub!(InvalidUndefBytes(Some(ptr))) => {
821 // Some byte was uninitialized, determine which
822 // element that byte belongs to so we can
824 let i = usize::try_from(ptr.offset.bytes() / layout.size.bytes())
826 self.path.push(PathElem::ArrayElem(i));
828 throw_validation_failure!("uninitialized bytes", self.path)
830 // Propagate upwards (that will also check for unexpected errors).
831 _ => return Err(err),
836 // Fast path for arrays and slices of ZSTs. We only need to check a single ZST element
837 // of an array and not all of them, because there's only a single value of a specific
838 // ZST type, so either validation fails for all elements or none.
839 ty::Array(tys, ..) | ty::Slice(tys) if self.ecx.layout_of(tys)?.is_zst() => {
840 // Validate just the first element
841 self.walk_aggregate(op, fields.take(1))?
844 self.walk_aggregate(op, fields)? // default handler
851 impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
852 fn validate_operand_internal(
854 op: OpTy<'tcx, M::PointerTag>,
856 ref_tracking_for_consts: Option<
857 &mut RefTracking<MPlaceTy<'tcx, M::PointerTag>, Vec<PathElem>>,
859 may_ref_to_static: bool,
860 ) -> InterpResult<'tcx> {
861 trace!("validate_operand_internal: {:?}, {:?}", *op, op.layout.ty);
863 // Construct a visitor
865 ValidityVisitor { path, ref_tracking_for_consts, may_ref_to_static, ecx: self };
867 // Try to cast to ptr *once* instead of all the time.
868 let op = self.force_op_ptr(op).unwrap_or(op);
871 match visitor.visit_value(op) {
873 // Pass through validation failures.
874 Err(err) if matches!(err.kind, err_ub!(ValidationFailure { .. })) => Err(err),
875 // Also pass through InvalidProgram, those just indicate that we could not
876 // validate and each caller will know best what to do with them.
877 Err(err) if matches!(err.kind, InterpError::InvalidProgram(_)) => Err(err),
878 // Avoid other errors as those do not show *where* in the value the issue lies.
879 Err(err) => bug!("Unexpected error during validation: {}", err),
883 /// This function checks the data at `op` to be const-valid.
884 /// `op` is assumed to cover valid memory if it is an indirect operand.
885 /// It will error if the bits at the destination do not match the ones described by the layout.
887 /// `ref_tracking` is used to record references that we encounter so that they
888 /// can be checked recursively by an outside driving loop.
890 /// `may_ref_to_static` controls whether references are allowed to point to statics.
892 pub fn const_validate_operand(
894 op: OpTy<'tcx, M::PointerTag>,
896 ref_tracking: &mut RefTracking<MPlaceTy<'tcx, M::PointerTag>, Vec<PathElem>>,
897 may_ref_to_static: bool,
898 ) -> InterpResult<'tcx> {
899 self.validate_operand_internal(op, path, Some(ref_tracking), may_ref_to_static)
902 /// This function checks the data at `op` to be runtime-valid.
903 /// `op` is assumed to cover valid memory if it is an indirect operand.
904 /// It will error if the bits at the destination do not match the ones described by the layout.
906 pub fn validate_operand(&self, op: OpTy<'tcx, M::PointerTag>) -> InterpResult<'tcx> {
907 self.validate_operand_internal(op, vec![], None, false)