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audit check_mul uses in interpret

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Ralf Jung 2022-03-27 19:49:52 -04:00
parent a421cbbead
commit 53c540a666
1 changed files with 7 additions and 1 deletions
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8
compiler/rustc_const_eval/src/interpret/intrinsics.rs
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@ -531,7 +531,9 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
) -> InterpResult<'tcx, Pointer<Option<M::PointerTag>>> { ) -> InterpResult<'tcx, Pointer<Option<M::PointerTag>>> {
// We cannot overflow i64 as a type's size must be <= isize::MAX. // We cannot overflow i64 as a type's size must be <= isize::MAX.
let pointee_size = i64::try_from(self.layout_of(pointee_ty)?.size.bytes()).unwrap(); let pointee_size = i64::try_from(self.layout_of(pointee_ty)?.size.bytes()).unwrap();
// The computed offset, in bytes, cannot overflow an isize. // The computed offset, in bytes, must not overflow an isize.
// `checked_mul` enforces a too small bound, but no actual allocation can be big enough for
// the difference to be noticeable.
let offset_bytes = let offset_bytes =
offset_count.checked_mul(pointee_size).ok_or(err_ub!(PointerArithOverflow))?; offset_count.checked_mul(pointee_size).ok_or(err_ub!(PointerArithOverflow))?;
// The offset being in bounds cannot rely on "wrapping around" the address space. // The offset being in bounds cannot rely on "wrapping around" the address space.
@ -563,6 +565,8 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
let count = self.read_scalar(&count)?.to_machine_usize(self)?; let count = self.read_scalar(&count)?.to_machine_usize(self)?;
let layout = self.layout_of(src.layout.ty.builtin_deref(true).unwrap().ty)?; let layout = self.layout_of(src.layout.ty.builtin_deref(true).unwrap().ty)?;
let (size, align) = (layout.size, layout.align.abi); let (size, align) = (layout.size, layout.align.abi);
// `checked_mul` enforces a too small bound (the correct one would probably be machine_isize_max),
// but no actual allocation can be big enough for the difference to be noticeable.
let size = size.checked_mul(count, self).ok_or_else(|| { let size = size.checked_mul(count, self).ok_or_else(|| {
err_ub_format!( err_ub_format!(
"overflow computing total size of `{}`", "overflow computing total size of `{}`",
@ -588,6 +592,8 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
let byte = self.read_scalar(&byte)?.to_u8()?; let byte = self.read_scalar(&byte)?.to_u8()?;
let count = self.read_scalar(&count)?.to_machine_usize(self)?; let count = self.read_scalar(&count)?.to_machine_usize(self)?;
// `checked_mul` enforces a too small bound (the correct one would probably be machine_isize_max),
// but no actual allocation can be big enough for the difference to be noticeable.
let len = layout let len = layout
.size .size
.checked_mul(count, self) .checked_mul(count, self)