From 8a36d12d3664ab0e882ce98bacd6f7f95000f6a2 Mon Sep 17 00:00:00 2001
From: Ralf Jung <post@ralfj.de>
Date: Fri, 29 Nov 2019 10:16:03 +0100
Subject: [PATCH] implement proper panicking for failed index check

---
 src/lib.rs         |  3 ++-
 src/machine.rs     | 10 ++++++++++
 src/shims/panic.rs | 40 +++++++++++++++++++++++++++++++++++++---
 3 files changed, 49 insertions(+), 4 deletions(-)

diff --git a/src/lib.rs b/src/lib.rs
index 05234e880f5..abed7ab9dfe 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -38,6 +38,7 @@ pub use crate::shims::dlsym::{Dlsym, EvalContextExt as DlsymEvalContextExt};
 pub use crate::shims::env::{EnvVars, EvalContextExt as EnvEvalContextExt};
 pub use crate::shims::fs::{FileHandler, EvalContextExt as FileEvalContextExt};
 pub use crate::shims::panic::{CatchUnwindData, EvalContextExt as PanicEvalContextExt};
+
 pub use crate::operator::EvalContextExt as OperatorEvalContextExt;
 pub use crate::range_map::RangeMap;
 pub use crate::helpers::{EvalContextExt as HelpersEvalContextExt};
@@ -45,7 +46,7 @@ pub use crate::mono_hash_map::MonoHashMap;
 pub use crate::stacked_borrows::{EvalContextExt as StackedBorEvalContextExt, Tag, Permission, Stack, Stacks, Item};
 pub use crate::machine::{
     PAGE_SIZE, STACK_ADDR, STACK_SIZE, NUM_CPUS,
-    MemoryExtra, AllocExtra, MiriMemoryKind, Evaluator, MiriEvalContext, MiriEvalContextExt,
+    MemoryExtra, AllocExtra, FrameData, MiriMemoryKind, Evaluator, MiriEvalContext, MiriEvalContextExt,
 };
 pub use crate::eval::{eval_main, create_ecx, MiriConfig, TerminationInfo};
 
diff --git a/src/machine.rs b/src/machine.rs
index 94ddee6fc09..07864ac4ee4 100644
--- a/src/machine.rs
+++ b/src/machine.rs
@@ -215,6 +215,16 @@ impl<'mir, 'tcx> Machine<'mir, 'tcx> for Evaluator<'tcx> {
         ecx.call_intrinsic(span, instance, args, ret, unwind)
     }
 
+    #[inline(always)]
+    fn assert_panic(
+        ecx: &mut InterpCx<'mir, 'tcx, Self>,
+        span: Span,
+        msg: &AssertMessage<'tcx>,
+        unwind: Option<mir::BasicBlock>,
+    ) -> InterpResult<'tcx> {
+        ecx.assert_panic(span, msg, unwind)
+    }
+
     #[inline(always)]
     fn binary_ptr_op(
         ecx: &rustc_mir::interpret::InterpCx<'mir, 'tcx, Self>,
diff --git a/src/shims/panic.rs b/src/shims/panic.rs
index 6cc9f176c8f..4b9cb6b4195 100644
--- a/src/shims/panic.rs
+++ b/src/shims/panic.rs
@@ -11,11 +11,12 @@
 //!   gets popped *during unwinding*, we take the panic payload and store it according to the extra
 //!   metadata we remembered when pushing said frame.
 
+use syntax::source_map::Span;
 use rustc::mir;
-use crate::*;
-use super::machine::FrameData;
+use rustc::ty::{self, layout::LayoutOf};
 use rustc_target::spec::PanicStrategy;
-use crate::rustc_target::abi::LayoutOf;
+
+use crate::*;
 
 /// Holds all of the relevant data for a call to
 /// `__rust_maybe_catch_panic`.
@@ -150,4 +151,37 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
         this.memory.extra.stacked_borrows.borrow_mut().end_call(extra.call_id);
         Ok(res)
     }
+
+    fn assert_panic(
+        &mut self,
+        span: Span,
+        msg: &AssertMessage<'tcx>,
+        unwind: Option<mir::BasicBlock>,
+    ) -> InterpResult<'tcx> {
+        use rustc::mir::interpret::PanicInfo::*;
+        let this = self.eval_context_mut();
+
+        match msg {
+            BoundsCheck { ref index, ref len } => {
+                // First arg: Caller location.
+                let location = this.alloc_caller_location_for_span(span)?;
+                // Second arg: index.
+                let index = this.read_scalar(this.eval_operand(index, None)?)?;
+                // Third arg: len.
+                let len = this.read_scalar(this.eval_operand(len, None)?)?;
+
+                // Call the lang item.
+                let panic_bounds_check = this.tcx.lang_items().panic_bounds_check_fn().unwrap();
+                let panic_bounds_check = ty::Instance::mono(this.tcx.tcx, panic_bounds_check);
+                this.call_function(
+                    panic_bounds_check,
+                    &[location.ptr, index.not_undef()?, len.not_undef()?],
+                    None,
+                    StackPopCleanup::Goto { ret: None, unwind },
+                )?;
+            }
+            _ => unimplemented!()
+        }
+        Ok(())
+    }
 }