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const-eval: disallow unwinding across functions that !fn_can_unwind()

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hyd-dev 2021-05-21 20:40:36 +08:00
parent ed20e1e533
commit 7b3e10c751
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4 changed files with 108 additions and 45 deletions
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37
compiler/rustc_mir/src/interpret/eval_context.rs
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@ -134,6 +134,15 @@ pub struct FrameInfo<'tcx> {
pub lint_root: Option<hir::HirId>,
}
/// Unwind information.
#[derive(Clone, Copy, Eq, PartialEq, Debug, HashStable)]
pub enum StackPopUnwind {
/// The cleanup block.
Cleanup(Option<mir::BasicBlock>),
/// Unwinding is not allowed (UB).
NotAllowed,
}
#[derive(Clone, Eq, PartialEq, Debug, HashStable)] // Miri debug-prints these
pub enum StackPopCleanup {
/// Jump to the next block in the caller, or cause UB if None (that's a function
@ -141,7 +150,7 @@ pub enum StackPopCleanup {
/// we can validate it at that layout.
/// `ret` stores the block we jump to on a normal return, while `unwind`
/// stores the block used for cleanup during unwinding.
Goto { ret: Option<mir::BasicBlock>, unwind: Option<mir::BasicBlock> },
Goto { ret: Option<mir::BasicBlock>, unwind: StackPopUnwind },
/// Just do nothing: Used by Main and for the `box_alloc` hook in miri.
/// `cleanup` says whether locals are deallocated. Static computation
/// wants them leaked to intern what they need (and just throw away
@ -807,9 +816,29 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
// In that case, we return early. We also avoid validation in that case,
// because this is CTFE and the final value will be thoroughly validated anyway.
let (cleanup, next_block) = match frame.return_to_block {
StackPopCleanup::Goto { ret, unwind } => {
(true, Some(if unwinding { unwind } else { ret }))
}
StackPopCleanup::Goto { ret, unwind } => (
true,
Some(if unwinding {
let def_id = frame.body.source.def_id();
match unwind {
StackPopUnwind::Cleanup(unwind)
// `fn_sig()` can't be used on closures, but closures always have
// "rust-call" ABI, which always allows unwinding anyway.
if self.tcx.is_closure(def_id) || self.fn_can_unwind(
self.tcx.codegen_fn_attrs(def_id).flags,
self.tcx.fn_sig(def_id).abi(),
) =>
{
unwind
}
_ => {
throw_ub_format!("unwind past a frame that does not allow unwinding")
}
}
} else {
ret
}),
),
StackPopCleanup::None { cleanup, .. } => (cleanup, None),
};