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offset, offset_from: allow zero-byte offset on arbitrary pointers

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This commit is contained in:
Ralf Jung 2024-05-09 12:35:11 +02:00
parent ba956ef4b0
commit 5c33a5690d
48 changed files with 200 additions and 475 deletions
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11
compiler/rustc_const_eval/src/interpret/validity.rs
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@ -434,6 +434,10 @@ impl<'rt, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> ValidityVisitor<'rt, 'mir, '
found_bytes: has.bytes()
},
);
// Make sure this is non-null. (ZST references can be dereferenceable and null.)
if self.ecx.scalar_may_be_null(Scalar::from_maybe_pointer(place.ptr(), self.ecx))? {
throw_validation_failure!(self.path, NullPtr { ptr_kind })
}
// Do not allow pointers to uninhabited types.
if place.layout.abi.is_uninhabited() {
let ty = place.layout.ty;
@ -456,8 +460,8 @@ impl<'rt, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> ValidityVisitor<'rt, 'mir, '
// `!` is a ZST and we want to validate it.
if let Ok((alloc_id, _offset, _prov)) = self.ecx.ptr_try_get_alloc_id(place.ptr()) {
let mut skip_recursive_check = false;
let alloc_actual_mutbl = mutability(self.ecx, alloc_id);
if let GlobalAlloc::Static(did) = self.ecx.tcx.global_alloc(alloc_id) {
if let Some(GlobalAlloc::Static(did)) = self.ecx.tcx.try_get_global_alloc(alloc_id)
{
let DefKind::Static { nested, .. } = self.ecx.tcx.def_kind(did) else { bug!() };
// Special handling for pointers to statics (irrespective of their type).
assert!(!self.ecx.tcx.is_thread_local_static(did));
@ -495,6 +499,7 @@ impl<'rt, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> ValidityVisitor<'rt, 'mir, '
// If this allocation has size zero, there is no actual mutability here.
let (size, _align, _alloc_kind) = self.ecx.get_alloc_info(alloc_id);
if size != Size::ZERO {
let alloc_actual_mutbl = mutability(self.ecx, alloc_id);
// Mutable pointer to immutable memory is no good.
if ptr_expected_mutbl == Mutability::Mut
&& alloc_actual_mutbl == Mutability::Not
@ -831,6 +836,8 @@ impl<'rt, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> ValueVisitor<'mir, 'tcx, M>
trace!("visit_value: {:?}, {:?}", *op, op.layout);
// Check primitive types -- the leaves of our recursive descent.
// We assume that the Scalar validity range does not restrict these values
// any further than `try_visit_primitive` does!
if self.try_visit_primitive(op)? {
return Ok(());
}