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Rollup merge of #95340 - RalfJung:pnvi, r=oli-obk

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interpret: with enforce_number_validity, ensure integers are truly Scalar::Int (i.e., no pointers)

This is required for https://github.com/rust-lang/miri/pull/2040

r? ```@oli-obk```
This commit is contained in:
Dylan DPC 2022-03-27 05:36:10 +02:00 • committed by GitHub
commit 178a09e672
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2 changed files with 8 additions and 4 deletions
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3
compiler/rustc_const_eval/src/interpret/eval_context.rs
View file

@ -444,6 +444,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
match scalar.try_to_int() {
Ok(int) => int.is_null(),
Err(_) => {
// Can only happen during CTFE.
let ptr = self.scalar_to_ptr(scalar);
match self.memory.ptr_try_get_alloc(ptr) {
Ok((alloc_id, offset, _)) => {
@ -455,7 +456,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
// Note that one-past-the-end (offset == size) is still inbounds, and never null.
offset > size
}
Err(offset) => offset == 0,
Err(_offset) => bug!("a non-int scalar is always a pointer"),
}
}
}

9
compiler/rustc_const_eval/src/interpret/validity.rs
View file

@ -21,7 +21,7 @@ use std::hash::Hash;
use super::{
alloc_range, CheckInAllocMsg, GlobalAlloc, InterpCx, InterpResult, MPlaceTy, Machine,
MemPlaceMeta, OpTy, ScalarMaybeUninit, ValueVisitor,
MemPlaceMeta, OpTy, Scalar, ScalarMaybeUninit, ValueVisitor,
};
macro_rules! throw_validation_failure {
@ -521,8 +521,11 @@ impl<'rt, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> ValidityVisitor<'rt, 'mir, '
// NOTE: Keep this in sync with the array optimization for int/float
// types below!
if M::enforce_number_validity(self.ecx) {
// Integers/floats in CTFE: Must be scalar bits, pointers are dangerous
let is_bits = value.check_init().map_or(false, |v| v.try_to_int().is_ok());
// Integers/floats with number validity: Must be scalar bits, pointers are dangerous.
// As a special exception we *do* match on a `Scalar` here, since we truly want
// to know its underlying representation (and *not* cast it to an integer).
let is_bits =
value.check_init().map_or(false, |v| matches!(v, Scalar::Int(..)));
if !is_bits {
throw_validation_failure!(self.path,
{ "{:x}", value } expected { "initialized plain (non-pointer) bytes" }