diff options
Diffstat (limited to 'compiler')
| -rw-r--r-- | compiler/rustc_mir_transform/src/ffi_unwind_calls.rs | 21 |
1 files changed, 21 insertions, 0 deletions
diff --git a/compiler/rustc_mir_transform/src/ffi_unwind_calls.rs b/compiler/rustc_mir_transform/src/ffi_unwind_calls.rs index d09d2a0b263..7728fdaffb0 100644 --- a/compiler/rustc_mir_transform/src/ffi_unwind_calls.rs +++ b/compiler/rustc_mir_transform/src/ffi_unwind_calls.rs @@ -136,6 +136,27 @@ fn required_panic_strategy(tcx: TyCtxt<'_>, cnum: CrateNum) -> Option<PanicStrat for def_id in tcx.hir().body_owners() { if tcx.has_ffi_unwind_calls(def_id) { + // Given that this crate is compiled in `-C panic=unwind`, the `AbortUnwindingCalls` + // MIR pass will not be run on FFI-unwind call sites, therefore a foreign exception + // can enter Rust through these sites. + // + // On the other hand, crates compiled with `-C panic=abort` expects that all Rust + // functions cannot unwind (whether it's caused by Rust panic or foreign exception), + // and this expectation mismatch can cause unsoundness (#96926). + // + // To address this issue, we enforce that if FFI-unwind calls are used in a crate + // compiled with `panic=unwind`, then the final panic strategy must be `panic=unwind`. + // This will ensure that no crates will have wrong unwindability assumption. + // + // It should be noted that it is okay to link `panic=unwind` into a `panic=abort` + // program if it contains no FFI-unwind calls. In such case foreign exception can only + // enter Rust in a `panic=abort` crate, which will lead to an abort. There will also + // be no exceptions generated from Rust, so the assumption which `panic=abort` crates + // make, that no Rust function can unwind, indeed holds for crates compiled with + // `panic=unwind` as well. In such case this function returns `None`, indicating that + // the crate does not require a particular final panic strategy, and can be freely + // linked to crates with either strategy (we need such ability for libstd and its + // dependencies). return Some(PanicStrategy::Unwind); } } |