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
;
16 use rustc_middle
::ty
::layout
::TyAndLayout
;
17 use rustc_span
::symbol
::{sym, Symbol}
;
18 use rustc_target
::abi
::{Abi, LayoutOf, Scalar as ScalarAbi, Size, VariantIdx, Variants}
;
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
)|+ => { $( $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 // Test if a range that wraps at overflow contains `test`
185 fn wrapping_range_contains(r
: &RangeInclusive
<u128
>, test
: u128
) -> bool
{
186 let (lo
, hi
) = r
.clone().into_inner();
189 (..=hi
).contains(&test
) || (lo
..).contains(&test
)
196 // Formats such that a sentence like "expected something {}" to mean
197 // "expected something <in the given range>" makes sense.
198 fn wrapping_range_format(r
: &RangeInclusive
<u128
>, max_hi
: u128
) -> String
{
199 let (lo
, hi
) = r
.clone().into_inner();
200 assert
!(hi
<= max_hi
);
202 format
!("less or equal to {}, or greater or equal to {}", hi
, lo
)
204 format
!("equal to {}", lo
)
206 assert
!(hi
< max_hi
, "should not be printing if the range covers everything");
207 format
!("less or equal to {}", hi
)
208 } else if hi
== max_hi
{
209 assert
!(lo
> 0, "should not be printing if the range covers everything");
210 format
!("greater or equal to {}", lo
)
212 format
!("in the range {:?}", r
)
216 struct ValidityVisitor
<'rt
, 'mir
, 'tcx
, M
: Machine
<'mir
, 'tcx
>> {
217 /// The `path` may be pushed to, but the part that is present when a function
218 /// starts must not be changed! `visit_fields` and `visit_array` rely on
219 /// this stack discipline.
221 ref_tracking
: Option
<&'rt
mut RefTracking
<MPlaceTy
<'tcx
, M
::PointerTag
>, Vec
<PathElem
>>>,
222 /// `None` indicates this is not validating for CTFE (but for runtime).
223 ctfe_mode
: Option
<CtfeValidationMode
>,
224 ecx
: &'rt InterpCx
<'mir
, 'tcx
, M
>,
227 impl<'rt
, 'mir
, 'tcx
: 'mir
, M
: Machine
<'mir
, 'tcx
>> ValidityVisitor
<'rt
, 'mir
, 'tcx
, M
> {
228 fn aggregate_field_path_elem(&mut self, layout
: TyAndLayout
<'tcx
>, field
: usize) -> PathElem
{
229 // First, check if we are projecting to a variant.
230 match layout
.variants
{
231 Variants
::Multiple { tag_field, .. }
=> {
232 if tag_field
== field
{
233 return match layout
.ty
.kind() {
234 ty
::Adt(def
, ..) if def
.is_enum() => PathElem
::EnumTag
,
235 ty
::Generator(..) => PathElem
::GeneratorTag
,
236 _
=> bug
!("non-variant type {:?}", layout
.ty
),
240 Variants
::Single { .. }
=> {}
243 // Now we know we are projecting to a field, so figure out which one.
244 match layout
.ty
.kind() {
245 // generators and closures.
246 ty
::Closure(def_id
, _
) | ty
::Generator(def_id
, _
, _
) => {
248 // FIXME this should be more descriptive i.e. CapturePlace instead of CapturedVar
249 // https://github.com/rust-lang/project-rfc-2229/issues/46
250 if let Some(local_def_id
) = def_id
.as_local() {
251 let tables
= self.ecx
.tcx
.typeck(local_def_id
);
252 if let Some(captured_place
) =
253 tables
.closure_min_captures_flattened(*def_id
).nth(field
)
255 // Sometimes the index is beyond the number of upvars (seen
257 let var_hir_id
= captured_place
.get_root_variable();
258 let node
= self.ecx
.tcx
.hir().get(var_hir_id
);
259 if let hir
::Node
::Binding(pat
) = node
{
260 if let hir
::PatKind
::Binding(_
, _
, ident
, _
) = pat
.kind
{
261 name
= Some(ident
.name
);
267 PathElem
::CapturedVar(name
.unwrap_or_else(|| {
268 // Fall back to showing the field index.
274 ty
::Tuple(_
) => PathElem
::TupleElem(field
),
277 ty
::Adt(def
, ..) if def
.is_enum() => {
278 // we might be projecting *to* a variant, or to a field *in* a variant.
279 match layout
.variants
{
280 Variants
::Single { index }
=> {
282 PathElem
::Field(def
.variants
[index
].fields
[field
].ident
.name
)
284 Variants
::Multiple { .. }
=> bug
!("we handled variants above"),
289 ty
::Adt(def
, _
) => PathElem
::Field(def
.non_enum_variant().fields
[field
].ident
.name
),
292 ty
::Array(..) | ty
::Slice(..) => PathElem
::ArrayElem(field
),
295 ty
::Dynamic(..) => PathElem
::DynDowncast
,
297 // nothing else has an aggregate layout
298 _
=> bug
!("aggregate_field_path_elem: got non-aggregate type {:?}", layout
.ty
),
305 f
: impl FnOnce(&mut Self) -> InterpResult
<'tcx
, R
>,
306 ) -> InterpResult
<'tcx
, R
> {
307 // Remember the old state
308 let path_len
= self.path
.len();
309 // Record new element
310 self.path
.push(elem
);
314 self.path
.truncate(path_len
);
319 fn check_wide_ptr_meta(
321 meta
: MemPlaceMeta
<M
::PointerTag
>,
322 pointee
: TyAndLayout
<'tcx
>,
323 ) -> InterpResult
<'tcx
> {
324 let tail
= self.ecx
.tcx
.struct_tail_erasing_lifetimes(pointee
.ty
, self.ecx
.param_env
);
327 let vtable
= self.ecx
.scalar_to_ptr(meta
.unwrap_meta());
328 // Direct call to `check_ptr_access_align` checks alignment even on CTFE machines.
330 self.ecx
.memory
.check_ptr_access_align(
332 3 * self.ecx
.tcx
.data_layout
.pointer_size
, // drop, size, align
333 self.ecx
.tcx
.data_layout
.pointer_align
.abi
,
334 CheckInAllocMsg
::InboundsTest
, // will anyway be replaced by validity message
337 err_ub
!(DanglingIntPointer(..)) |
338 err_ub
!(PointerUseAfterFree(..)) =>
339 { "dangling vtable pointer in wide pointer" }
,
340 err_ub
!(AlignmentCheckFailed { .. }
) =>
341 { "unaligned vtable pointer in wide pointer" }
,
342 err_ub
!(PointerOutOfBounds { .. }
) =>
343 { "too small vtable" }
,
346 self.ecx
.read_drop_type_from_vtable(vtable
),
348 err_ub
!(DanglingIntPointer(..)) |
349 err_ub
!(InvalidFunctionPointer(..)) =>
350 { "invalid drop function pointer in vtable (not pointing to a function)" }
,
351 err_ub
!(InvalidVtableDropFn(..)) =>
352 { "invalid drop function pointer in vtable (function has incompatible signature)" }
,
355 self.ecx
.read_size_and_align_from_vtable(vtable
),
357 err_ub
!(InvalidVtableSize
) =>
358 { "invalid vtable: size is bigger than largest supported object" }
,
359 err_ub
!(InvalidVtableAlignment(msg
)) =>
360 { "invalid vtable: alignment {}
", msg },
361 err_unsup!(ReadPointerAsBytes) => { "invalid size or align in vtable" },
363 // FIXME: More checks for the vtable.
365 ty::Slice(..) | ty::Str => {
366 let _len = try_validation!(
367 meta.unwrap_meta().to_machine_usize(self.ecx),
369 err_unsup!(ReadPointerAsBytes) => { "non-integer slice length in wide pointer" },
371 // We do not check that `len * elem_size <= isize::MAX`:
372 // that is only required for references, and there it falls out of the
373 // "dereferenceable
" check performed by Stacked Borrows.
376 // Unsized, but not wide.
378 _ => bug!("Unexpected
unsized type tail
: {:?}
", tail),
384 /// Check a reference or `Box`.
385 fn check_safe_pointer(
387 value: &OpTy<'tcx, M::PointerTag>,
389 ) -> InterpResult<'tcx> {
390 let value = try_validation!(
391 self.ecx.read_immediate(value),
393 err_unsup!(ReadPointerAsBytes) => { "part of a pointer" } expected { "a proper pointer or integer value" },
395 // Handle wide pointers.
396 // Check metadata early, for better diagnostics
397 let place = try_validation!(
398 self.ecx.ref_to_mplace(&value),
400 err_ub!(InvalidUninitBytes(None)) => { "uninitialized {}", kind
},
402 if place
.layout
.is_unsized() {
403 self.check_wide_ptr_meta(place
.meta
, place
.layout
)?
;
405 // Make sure this is dereferenceable and all.
406 let size_and_align
= try_validation
!(
407 self.ecx
.size_and_align_of_mplace(&place
),
409 err_ub
!(InvalidMeta(msg
)) => { "invalid {} metadata
: {}
", kind, msg },
411 let (size, align) = size_and_align
412 // for the purpose of validity, consider foreign types to have
413 // alignment and size determined by the layout (size will be 0,
414 // alignment should take attributes into account).
415 .unwrap_or_else(|| (place.layout.size, place.layout.align.abi));
416 // Direct call to `check_ptr_access_align` checks alignment even on CTFE machines.
418 self.ecx.memory.check_ptr_access_align(
422 CheckInAllocMsg::InboundsTest, // will anyway be replaced by validity message
425 err_ub!(AlignmentCheckFailed { required, has }) =>
427 "an unaligned {}
(required {} byte alignment but found {}
)",
432 err_ub!(DanglingIntPointer(0, _)) =>
433 { "a null {}", kind
},
434 err_ub
!(DanglingIntPointer(i
, _
)) =>
435 { "a dangling {}
(address
0x{:x} is unallocated
)", kind, i },
436 err_ub!(PointerOutOfBounds { .. }) =>
437 { "a dangling {} (going beyond the bounds of its allocation)", kind
},
438 // This cannot happen during const-eval (because interning already detects
439 // dangling pointers), but it can happen in Miri.
440 err_ub
!(PointerUseAfterFree(..)) =>
441 { "a dangling {}
(use-after
-free
)", kind },
443 // Recursive checking
444 if let Some(ref mut ref_tracking) = self.ref_tracking {
445 // Proceed recursively even for ZST, no reason to skip them!
446 // `!` is a ZST and we want to validate it.
447 // Skip validation entirely for some external statics
448 if let Ok((alloc_id, _offset, _ptr)) = self.ecx.memory.ptr_try_get_alloc(place.ptr) {
450 let alloc_kind = self.ecx.tcx.get_global_alloc(alloc_id);
451 if let Some(GlobalAlloc::Static(did)) = alloc_kind {
452 assert!(!self.ecx.tcx.is_thread_local_static(did));
453 assert!(self.ecx.tcx.is_static(did));
456 Some(CtfeValidationMode::Const { allow_static_ptrs: false, .. })
458 // See const_eval::machine::MemoryExtra::can_access_statics for why
459 // this check is so important.
460 // This check is reachable when the const just referenced the static,
461 // but never read it (so we never entered `before_access_global`).
462 throw_validation_failure!(self.path,
463 { "a {} pointing to a static variable", kind
}
466 // We skip checking other statics. These statics must be sound by
467 // themselves, and the only way to get broken statics here is by using
469 // The reasons we don't check other statics is twofold. For one, in all
470 // sound cases, the static was already validated on its own, and second, we
471 // trigger cycle errors if we try to compute the value of the other static
472 // and that static refers back to us.
473 // We might miss const-invalid data,
474 // but things are still sound otherwise (in particular re: consts
475 // referring to statics).
479 let path
= &self.path
;
480 ref_tracking
.track(place
, || {
481 // We need to clone the path anyway, make sure it gets created
482 // with enough space for the additional `Deref`.
483 let mut new_path
= Vec
::with_capacity(path
.len() + 1);
484 new_path
.clone_from(path
);
485 new_path
.push(PathElem
::Deref
);
494 op
: &OpTy
<'tcx
, M
::PointerTag
>,
495 ) -> InterpResult
<'tcx
, ScalarMaybeUninit
<M
::PointerTag
>> {
497 self.ecx
.read_scalar(op
),
499 err_unsup
!(ReadPointerAsBytes
) => { "(potentially part of) a pointer" } expected { "plain (non-pointer) bytes" }
,
503 /// Check if this is a value of primitive type, and if yes check the validity of the value
504 /// at that type. Return `true` if the type is indeed primitive.
505 fn try_visit_primitive(
507 value
: &OpTy
<'tcx
, M
::PointerTag
>,
508 ) -> InterpResult
<'tcx
, bool
> {
509 // Go over all the primitive types
510 let ty
= value
.layout
.ty
;
513 let value
= self.read_scalar(value
)?
;
517 err_ub
!(InvalidBool(..)) | err_ub
!(InvalidUninitBytes(None
)) =>
518 { "{}
", value } expected { "a boolean" },
523 let value = self.read_scalar(value)?;
527 err_ub!(InvalidChar(..)) | err_ub!(InvalidUninitBytes(None)) =>
528 { "{}", value
} expected { "a valid unicode scalar value (in `0..=0x10FFFF` but not in `0xD800..=0xDFFF`)" }
,
532 ty
::Float(_
) | ty
::Int(_
) | ty
::Uint(_
) => {
533 let value
= self.read_scalar(value
)?
;
534 // NOTE: Keep this in sync with the array optimization for int/float
536 if self.ctfe_mode
.is_some() {
537 // Integers/floats in CTFE: Must be scalar bits, pointers are dangerous
538 let is_bits
= value
.check_init().map_or(false, |v
| v
.try_to_int().is_ok());
540 throw_validation_failure
!(self.path
,
541 { "{}
", value } expected { "initialized plain (non-pointer) bytes" }
545 // At run-time, for now, we accept *anything* for these types, including
546 // uninit. We should fix that, but let's start low.
551 // We are conservative with uninit for integers, but try to
552 // actually enforce the strict rules for raw pointers (mostly because
553 // that lets us re-use `ref_to_mplace`).
554 let place = try_validation!(
555 self.ecx.read_immediate(value).and_then(|ref i| self.ecx.ref_to_mplace(i)),
557 err_ub!(InvalidUninitBytes(None)) => { "uninitialized raw pointer" },
558 err_unsup!(ReadPointerAsBytes) => { "part of a pointer" } expected { "a proper pointer or integer value" },
560 if place.layout.is_unsized() {
561 self.check_wide_ptr_meta(place.meta, place.layout)?;
565 ty::Ref(_, ty, mutbl) => {
566 if matches!(self.ctfe_mode, Some(CtfeValidationMode::Const { .. }))
567 && *mutbl == hir::Mutability::Mut
569 // A mutable reference inside a const? That does not seem right (except if it is
571 let layout = self.ecx.layout_of(ty)?;
572 if !layout.is_zst() {
573 throw_validation_failure!(self.path, { "mutable reference in a `const`" });
576 self.check_safe_pointer(value, "reference
")?;
579 ty::Adt(def, ..) if def.is_box() => {
580 self.check_safe_pointer(value, "box")?;
584 let value = try_validation!(
585 self.ecx.read_immediate(value),
587 err_unsup!(ReadPointerAsBytes) => { "part of a pointer" } expected { "a proper pointer or integer value" },
589 // Make sure we print a `ScalarMaybeUninit` (and not an `ImmTy`) in the error
591 let value = value.to_scalar_or_uninit();
592 let _fn = try_validation!(
593 value.check_init().and_then(|ptr| self.ecx.memory.get_fn(self.ecx.scalar_to_ptr(ptr))),
595 err_ub!(DanglingIntPointer(..)) |
596 err_ub!(InvalidFunctionPointer(..)) |
597 err_ub!(InvalidUninitBytes(None)) =>
598 { "{}", value
} expected { "a function pointer" }
,
600 // FIXME: Check if the signature matches
603 ty
::Never
=> throw_validation_failure
!(self.path
, { "a value of the never type `!`" }
),
604 ty
::Foreign(..) | ty
::FnDef(..) => {
608 // The above should be all the primitive types. The rest is compound, we
609 // check them by visiting their fields/variants.
617 | ty
::Generator(..) => Ok(false),
618 // Some types only occur during typechecking, they have no layout.
619 // We should not see them here and we could not check them anyway.
622 | ty
::Placeholder(..)
627 | ty
::GeneratorWitness(..) => bug
!("Encountered invalid type {:?}", ty
),
633 op
: &OpTy
<'tcx
, M
::PointerTag
>,
634 scalar_layout
: &ScalarAbi
,
635 ) -> InterpResult
<'tcx
> {
636 let value
= self.read_scalar(op
)?
;
637 let valid_range
= &scalar_layout
.valid_range
;
638 let (lo
, hi
) = valid_range
.clone().into_inner();
639 // Determine the allowed range
640 // `max_hi` is as big as the size fits
641 let max_hi
= u128
::MAX
>> (128 - op
.layout
.size
.bits());
642 assert
!(hi
<= max_hi
);
643 // We could also write `(hi + 1) % (max_hi + 1) == lo` but `max_hi + 1` overflows for `u128`
644 if (lo
== 0 && hi
== max_hi
) || (hi
+ 1 == lo
) {
648 // At least one value is excluded. Get the bits.
649 let value
= try_validation
!(
652 err_ub
!(InvalidUninitBytes(None
)) => { "{}
", value }
653 expected { "something {}", wrapping_range_format(valid_range
, max_hi
) },
655 let bits
= match value
.try_to_int() {
657 // So this is a pointer then, and casting to an int failed.
658 // Can only happen during CTFE.
659 let ptr
= self.ecx
.scalar_to_ptr(value
);
660 if lo
== 1 && hi
== max_hi
{
661 // Only null is the niche. So make sure the ptr is NOT null.
662 if self.ecx
.memory
.ptr_may_be_null(ptr
) {
663 throw_validation_failure
!(self.path
,
664 { "a potentially null pointer" }
666 "something that cannot possibly fail to be {}",
667 wrapping_range_format(valid_range
, max_hi
)
673 // Conservatively, we reject, because the pointer *could* have a bad
675 throw_validation_failure
!(self.path
,
678 "something that cannot possibly fail to be {}",
679 wrapping_range_format(valid_range
, max_hi
)
684 Ok(int
) => int
.assert_bits(op
.layout
.size
),
686 // Now compare. This is slightly subtle because this is a special "wrap-around" range.
687 if wrapping_range_contains(&valid_range
, bits
) {
690 throw_validation_failure
!(self.path
,
692 expected { "something {}", wrapping_range_format(valid_range
, max_hi
) }
698 impl<'rt
, 'mir
, 'tcx
: 'mir
, M
: Machine
<'mir
, 'tcx
>> ValueVisitor
<'mir
, 'tcx
, M
>
699 for ValidityVisitor
<'rt
, 'mir
, 'tcx
, M
>
701 type V
= OpTy
<'tcx
, M
::PointerTag
>;
704 fn ecx(&self) -> &InterpCx
<'mir
, 'tcx
, M
> {
708 fn read_discriminant(
710 op
: &OpTy
<'tcx
, M
::PointerTag
>,
711 ) -> InterpResult
<'tcx
, VariantIdx
> {
712 self.with_elem(PathElem
::EnumTag
, move |this
| {
714 this
.ecx
.read_discriminant(op
),
716 err_ub
!(InvalidTag(val
)) =>
717 { "{}
", val } expected { "a valid enum tag" },
718 err_ub!(InvalidUninitBytes(None)) =>
719 { "uninitialized bytes" } expected { "a valid enum tag" },
720 err_unsup!(ReadPointerAsBytes) =>
721 { "a pointer" } expected { "a valid enum tag" },
730 old_op: &OpTy<'tcx, M::PointerTag>,
732 new_op: &OpTy<'tcx, M::PointerTag>,
733 ) -> InterpResult<'tcx> {
734 let elem = self.aggregate_field_path_elem(old_op.layout, field);
735 self.with_elem(elem, move |this| this.visit_value(new_op))
741 old_op: &OpTy<'tcx, M::PointerTag>,
742 variant_id: VariantIdx,
743 new_op: &OpTy<'tcx, M::PointerTag>,
744 ) -> InterpResult<'tcx> {
745 let name = match old_op.layout.ty.kind() {
746 ty::Adt(adt, _) => PathElem::Variant(adt.variants[variant_id].ident.name),
747 // Generators also have variants
748 ty::Generator(..) => PathElem::GeneratorState(variant_id),
749 _ => bug!("Unexpected
type with variant
: {:?}
", old_op.layout.ty),
751 self.with_elem(name, move |this| this.visit_value(new_op))
757 _op: &OpTy<'tcx, M::PointerTag>,
758 _fields: NonZeroUsize,
759 ) -> InterpResult<'tcx> {
764 fn visit_value(&mut self, op: &OpTy<'tcx, M::PointerTag>) -> InterpResult<'tcx> {
765 trace!("visit_value
: {:?}
, {:?}
", *op, op.layout);
767 // Check primitive types -- the leafs of our recursive descend.
768 if self.try_visit_primitive(op)? {
771 // Sanity check: `builtin_deref` does not know any pointers that are not primitive.
772 assert!(op.layout.ty.builtin_deref(true).is_none());
774 // Special check preventing `UnsafeCell` in the inner part of constants
775 if let Some(def) = op.layout.ty.ty_adt_def() {
776 if matches!(self.ctfe_mode, Some(CtfeValidationMode::Const { inner: true, .. }))
777 && Some(def.did) == self.ecx.tcx.lang_items().unsafe_cell_type()
779 throw_validation_failure!(self.path, { "`UnsafeCell` in a `const`" });
783 // Recursively walk the value at its type.
784 self.walk_value(op)?;
786 // *After* all of this, check the ABI. We need to check the ABI to handle
787 // types like `NonNull` where the `Scalar` info is more restrictive than what
788 // the fields say (`rustc_layout_scalar_valid_range_start`).
789 // But in most cases, this will just propagate what the fields say,
790 // and then we want the error to point at the field -- so, first recurse,
793 // FIXME: We could avoid some redundant checks here. For newtypes wrapping
794 // scalars, we do the same check on every "level
" (e.g., first we check
795 // MyNewtype and then the scalar in there).
796 match op.layout.abi {
797 Abi::Uninhabited => {
798 throw_validation_failure!(self.path,
799 { "a value of uninhabited type {:?}", op
.layout
.ty
}
802 Abi
::Scalar(ref scalar_layout
) => {
803 self.visit_scalar(op
, scalar_layout
)?
;
805 Abi
::ScalarPair { .. }
| Abi
::Vector { .. }
=> {
806 // These have fields that we already visited above, so we already checked
807 // all their scalar-level restrictions.
808 // There is also no equivalent to `rustc_layout_scalar_valid_range_start`
809 // that would make skipping them here an issue.
811 Abi
::Aggregate { .. }
=> {
821 op
: &OpTy
<'tcx
, M
::PointerTag
>,
822 fields
: impl Iterator
<Item
= InterpResult
<'tcx
, Self::V
>>,
823 ) -> InterpResult
<'tcx
> {
824 match op
.layout
.ty
.kind() {
826 let mplace
= op
.assert_mem_place(); // strings are never immediate
827 let len
= mplace
.len(self.ecx
)?
;
829 self.ecx
.memory
.read_bytes(mplace
.ptr
, Size
::from_bytes(len
)),
831 err_ub
!(InvalidUninitBytes(..)) => { "uninitialized data in `str`" }
,
832 err_unsup
!(ReadPointerAsBytes
) => { "a pointer in `str`" }
,
835 ty
::Array(tys
, ..) | ty
::Slice(tys
)
836 // This optimization applies for types that can hold arbitrary bytes (such as
837 // integer and floating point types) or for structs or tuples with no fields.
838 // FIXME(wesleywiser) This logic could be extended further to arbitrary structs
839 // or tuples made up of integer/floating point types or inhabited ZSTs with no
841 if matches
!(tys
.kind(), ty
::Int(..) | ty
::Uint(..) | ty
::Float(..))
844 // Optimized handling for arrays of integer/float type.
846 // Arrays cannot be immediate, slices are never immediate.
847 let mplace
= op
.assert_mem_place();
848 // This is the length of the array/slice.
849 let len
= mplace
.len(self.ecx
)?
;
850 // This is the element type size.
851 let layout
= self.ecx
.layout_of(tys
)?
;
852 // This is the size in bytes of the whole array. (This checks for overflow.)
853 let size
= layout
.size
* len
;
855 // Optimization: we just check the entire range at once.
856 // NOTE: Keep this in sync with the handling of integer and float
857 // types above, in `visit_primitive`.
858 // In run-time mode, we accept pointers in here. This is actually more
859 // permissive than a per-element check would be, e.g., we accept
860 // an &[u8] that contains a pointer even though bytewise checking would
861 // reject it. However, that's good: We don't inherently want
862 // to reject those pointers, we just do not have the machinery to
863 // talk about parts of a pointer.
864 // We also accept uninit, for consistency with the slow path.
865 let alloc
= match self.ecx
.memory
.get(mplace
.ptr
, size
, mplace
.align
)?
{
868 // Size 0, nothing more to check.
873 match alloc
.check_bytes(
874 alloc_range(Size
::ZERO
, size
),
875 /*allow_uninit_and_ptr*/ self.ctfe_mode
.is_none(),
877 // In the happy case, we needn't check anything else.
879 // Some error happened, try to provide a more detailed description.
881 // For some errors we might be able to provide extra information.
882 // (This custom logic does not fit the `try_validation!` macro.)
884 err_ub
!(InvalidUninitBytes(Some((_alloc_id
, access
)))) => {
885 // Some byte was uninitialized, determine which
886 // element that byte belongs to so we can
888 let i
= usize::try_from(
889 access
.uninit_offset
.bytes() / layout
.size
.bytes(),
892 self.path
.push(PathElem
::ArrayElem(i
));
894 throw_validation_failure
!(self.path
, { "uninitialized bytes" }
)
896 err_unsup
!(ReadPointerAsBytes
) => {
897 throw_validation_failure
!(self.path
, { "a pointer" } expected { "plain (non-pointer) bytes" }
)
900 // Propagate upwards (that will also check for unexpected errors).
901 _
=> return Err(err
),
906 // Fast path for arrays and slices of ZSTs. We only need to check a single ZST element
907 // of an array and not all of them, because there's only a single value of a specific
908 // ZST type, so either validation fails for all elements or none.
909 ty
::Array(tys
, ..) | ty
::Slice(tys
) if self.ecx
.layout_of(tys
)?
.is_zst() => {
910 // Validate just the first element (if any).
911 self.walk_aggregate(op
, fields
.take(1))?
914 self.walk_aggregate(op
, fields
)?
// default handler
921 impl<'mir
, 'tcx
: 'mir
, M
: Machine
<'mir
, 'tcx
>> InterpCx
<'mir
, 'tcx
, M
> {
922 fn validate_operand_internal(
924 op
: &OpTy
<'tcx
, M
::PointerTag
>,
926 ref_tracking
: Option
<&mut RefTracking
<MPlaceTy
<'tcx
, M
::PointerTag
>, Vec
<PathElem
>>>,
927 ctfe_mode
: Option
<CtfeValidationMode
>,
928 ) -> InterpResult
<'tcx
> {
929 trace
!("validate_operand_internal: {:?}, {:?}", *op
, op
.layout
.ty
);
931 // Construct a visitor
932 let mut visitor
= ValidityVisitor { path, ref_tracking, ctfe_mode, ecx: self }
;
935 match visitor
.visit_value(&op
) {
937 // Pass through validation failures.
938 Err(err
) if matches
!(err
.kind(), err_ub
!(ValidationFailure { .. }
)) => Err(err
),
939 // Also pass through InvalidProgram, those just indicate that we could not
940 // validate and each caller will know best what to do with them.
941 Err(err
) if matches
!(err
.kind(), InterpError
::InvalidProgram(_
)) => Err(err
),
942 // Avoid other errors as those do not show *where* in the value the issue lies.
944 err
.print_backtrace();
945 bug
!("Unexpected error during validation: {}", err
);
950 /// This function checks the data at `op` to be const-valid.
951 /// `op` is assumed to cover valid memory if it is an indirect operand.
952 /// It will error if the bits at the destination do not match the ones described by the layout.
954 /// `ref_tracking` is used to record references that we encounter so that they
955 /// can be checked recursively by an outside driving loop.
957 /// `constant` controls whether this must satisfy the rules for constants:
958 /// - no pointers to statics.
959 /// - no `UnsafeCell` or non-ZST `&mut`.
961 pub fn const_validate_operand(
963 op
: &OpTy
<'tcx
, M
::PointerTag
>,
965 ref_tracking
: &mut RefTracking
<MPlaceTy
<'tcx
, M
::PointerTag
>, Vec
<PathElem
>>,
966 ctfe_mode
: CtfeValidationMode
,
967 ) -> InterpResult
<'tcx
> {
968 self.validate_operand_internal(op
, path
, Some(ref_tracking
), Some(ctfe_mode
))
971 /// This function checks the data at `op` to be runtime-valid.
972 /// `op` is assumed to cover valid memory if it is an indirect operand.
973 /// It will error if the bits at the destination do not match the ones described by the layout.
975 pub fn validate_operand(&self, op
: &OpTy
<'tcx
, M
::PointerTag
>) -> InterpResult
<'tcx
> {
976 self.validate_operand_internal(op
, vec
![], None
, None
)