From 67ec96955f4a08c1005bda843d48ca73ea171c9e Mon Sep 17 00:00:00 2001 From: Ralf Jung Date: Sun, 5 Jun 2022 11:14:30 -0400 Subject: [PATCH] validating the vtable can lead to Stacked Borrows errors --- compiler/rustc_const_eval/src/interpret/validity.rs | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/compiler/rustc_const_eval/src/interpret/validity.rs b/compiler/rustc_const_eval/src/interpret/validity.rs index b39a33aff097e..630281bb09254 100644 --- a/compiler/rustc_const_eval/src/interpret/validity.rs +++ b/compiler/rustc_const_eval/src/interpret/validity.rs @@ -338,6 +338,10 @@ impl<'rt, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> ValidityVisitor<'rt, 'mir, ' { "invalid drop function pointer in vtable (not pointing to a function)" }, err_ub!(InvalidVtableDropFn(..)) => { "invalid drop function pointer in vtable (function has incompatible signature)" }, + // Stacked Borrows errors can happen here, see https://github.com/rust-lang/miri/issues/2123. + // (We assume there are no other MachineStop errors possible here.) + InterpError::MachineStop(_) => + { "vtable pointer does not have permission to read drop function pointer" }, ); try_validation!( self.ecx.read_size_and_align_from_vtable(vtable), @@ -347,6 +351,10 @@ impl<'rt, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> ValidityVisitor<'rt, 'mir, ' err_ub!(InvalidVtableAlignment(msg)) => { "invalid vtable: alignment {}", msg }, err_unsup!(ReadPointerAsBytes) => { "invalid size or align in vtable" }, + // Stacked Borrows errors can happen here, see https://github.com/rust-lang/miri/issues/2123. + // (We assume there are no other MachineStop errors possible here.) + InterpError::MachineStop(_) => + { "vtable pointer does not have permission to read size and alignment" }, ); // FIXME: More checks for the vtable. }