bjoernager/rust
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const validation: fix ICE on dangling ZST reference

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This commit is contained in:
Ralf Jung 2024-06-13 21:01:00 +02:00
parent f1586001ac
commit a6907100de
5 changed files with 49 additions and 8 deletions
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16
compiler/rustc_const_eval/src/interpret/validity.rs
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@ -29,7 +29,7 @@ use rustc_target::abi::{
use std::hash::Hash;
use super::{
err_ub, format_interp_error, machine::AllocMap, throw_ub, AllocId, CheckInAllocMsg,
err_ub, format_interp_error, machine::AllocMap, throw_ub, AllocId, AllocKind, CheckInAllocMsg,
GlobalAlloc, ImmTy, Immediate, InterpCx, InterpResult, MPlaceTy, Machine, MemPlaceMeta, OpTy,
Pointer, Projectable, Scalar, ValueVisitor,
};
@ -413,8 +413,6 @@ impl<'rt, 'tcx, M: Machine<'tcx>> ValidityVisitor<'rt, 'tcx, M> {
Ub(PointerOutOfBounds { .. }) => DanglingPtrOutOfBounds {
ptr_kind
},
// This cannot happen during const-eval (because interning already detects
// dangling pointers), but it can happen in Miri.
Ub(PointerUseAfterFree(..)) => DanglingPtrUseAfterFree {
ptr_kind,
},
@ -493,9 +491,17 @@ impl<'rt, 'tcx, M: Machine<'tcx>> ValidityVisitor<'rt, 'tcx, M> {
}
}
// Mutability check.
// Dangling and Mutability check.
let (size, _align, alloc_kind) = self.ecx.get_alloc_info(alloc_id);
if alloc_kind == AllocKind::Dead {
// This can happen for zero-sized references. We can't have *any* references to non-existing
// allocations though, interning rejects them all as the rest of rustc isn't happy with them...
// so we throw an error, even though this isn't really UB.
// A potential future alternative would be to resurrect this as a zero-sized allocation
// (which codegen will then compile to an aligned dummy pointer anyway).
throw_validation_failure!(self.path, DanglingPtrUseAfterFree { ptr_kind });
}
// 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.