bjoernager/rust
bjoernager/rust
1
Fork 0
Code Activity

Turn incorrect vtable size/alignment errors into hard const-UB errors

Browse source 
They were "freeform const UB" error message, but could reach validation
and trigger ICEs there. We now catch them during validation to avoid
that.
This commit is contained in:
Rémy Rakic 2021-06-12 13:13:38 +02:00
parent 0f6ba39fd8
commit cae1918b29
3 changed files with 20 additions and 11 deletions
Download patch file Download diff file Expand all files Collapse all files

13
compiler/rustc_mir/src/interpret/traits.rs
View file

@ -137,9 +137,10 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
// The drop function takes `*mut T` where `T` is the type being dropped, so get that.
let args = fn_sig.inputs();
if args.len() != 1 {
throw_ub!(InvalidDropFn(fn_sig));
throw_ub!(InvalidVtableDropFn(fn_sig));
}
let ty = args[0].builtin_deref(true).ok_or_else(|| err_ub!(InvalidDropFn(fn_sig)))?.ty;
let ty =
args[0].builtin_deref(true).ok_or_else(|| err_ub!(InvalidVtableDropFn(fn_sig)))?.ty;
Ok((drop_instance, ty))
}
@ -158,14 +159,10 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
let size = u64::try_from(self.force_bits(size, pointer_size)?).unwrap();
let align = vtable.read_ptr_sized(pointer_size * 2)?.check_init()?;
let align = u64::try_from(self.force_bits(align, pointer_size)?).unwrap();
let align = Align::from_bytes(align)
.map_err(|e| err_ub_format!("invalid vtable: alignment {}", e))?;
let align = Align::from_bytes(align).map_err(|e| err_ub!(InvalidVtableAlignment(e)))?;
if size >= self.tcx.data_layout.obj_size_bound() {
throw_ub_format!(
"invalid vtable: \
size is bigger than largest supported object"
);
throw_ub!(InvalidVtableSize);
}
Ok((Size::from_bytes(size), align))
}

6
compiler/rustc_mir/src/interpret/validity.rs
View file

@ -349,12 +349,16 @@ impl<'rt, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> ValidityVisitor<'rt, 'mir, '
err_ub!(InvalidFunctionPointer(..)) |
err_unsup!(ReadBytesAsPointer) =>
{ "invalid drop function pointer in vtable (not pointing to a function)" },
err_ub!(InvalidDropFn(..)) =>
err_ub!(InvalidVtableDropFn(..)) =>
{ "invalid drop function pointer in vtable (function has incompatible signature)" },
);
try_validation!(
self.ecx.read_size_and_align_from_vtable(vtable),
self.path,
err_ub!(InvalidVtableSize) =>
{ "invalid vtable: size is bigger than largest supported object" },
err_ub!(InvalidVtableAlignment(msg)) =>
{ "invalid vtable: alignment {}", msg },
err_unsup!(ReadPointerAsBytes) => { "invalid size or align in vtable" },
);
// FIXME: More checks for the vtable.