Rollup merge of rust-lang#107756 - RalfJung:miri-out-of-addresses, r=…

…oli-obk

miri: fix ICE when running out of address space

Fixes rust-lang/miri#2769
r? `@oli-obk`

I didn't add a test since that requires oli-obk/ui_test#38 (host must be 64bit and target 32bit). Also the test takes ~30s, so I am not sure if we want to have it in the test suite?

compiler/rustc_const_eval/src/interpret/intrinsics/caller_location.rs

@@ -78,13 +78,16 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         col: u32,
     ) -> MPlaceTy<'tcx, M::Provenance> {
         let loc_details = &self.tcx.sess.opts.unstable_opts.location_detail;
+        // This can fail if rustc runs out of memory right here. Trying to emit an error would be
+        // pointless, since that would require allocating more memory than these short strings.
         let file = if loc_details.file {
             self.allocate_str(filename.as_str(), MemoryKind::CallerLocation, Mutability::Not)
+                .unwrap()
         } else {
             // FIXME: This creates a new allocation each time. It might be preferable to
             // perform this allocation only once, and re-use the `MPlaceTy`.
             // See https://github.com/rust-lang/rust/pull/89920#discussion_r730012398
-            self.allocate_str("<redacted>", MemoryKind::CallerLocation, Mutability::Not)
+            self.allocate_str("<redacted>", MemoryKind::CallerLocation, Mutability::Not).unwrap()
         };
         let line = if loc_details.line { Scalar::from_u32(line) } else { Scalar::from_u32(0) };
         let col = if loc_details.column { Scalar::from_u32(col) } else { Scalar::from_u32(0) };
@@ -95,8 +98,6 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
             .bound_type_of(self.tcx.require_lang_item(LangItem::PanicLocation, None))
             .subst(*self.tcx, self.tcx.mk_substs([self.tcx.lifetimes.re_erased.into()].iter()));
         let loc_layout = self.layout_of(loc_ty).unwrap();
-        // This can fail if rustc runs out of memory right here. Trying to emit an error would be
-        // pointless, since that would require allocating more memory than a Location.
         let location = self.allocate(loc_layout, MemoryKind::CallerLocation).unwrap();
 
         // Initialize fields.

compiler/rustc_const_eval/src/interpret/machine.rs

@@ -291,7 +291,7 @@ pub trait Machine<'mir, 'tcx>: Sized {
     fn adjust_alloc_base_pointer(
         ecx: &InterpCx<'mir, 'tcx, Self>,
         ptr: Pointer,
-    ) -> Pointer<Self::Provenance>;
+    ) -> InterpResult<'tcx, Pointer<Self::Provenance>>;
 
     /// "Int-to-pointer cast"
     fn ptr_from_addr_cast(
@@ -505,8 +505,8 @@ pub macro compile_time_machine(<$mir: lifetime, $tcx: lifetime>) {
     fn adjust_alloc_base_pointer(
         _ecx: &InterpCx<$mir, $tcx, Self>,
         ptr: Pointer<AllocId>,
-    ) -> Pointer<AllocId> {
-        ptr
+    ) -> InterpResult<$tcx, Pointer<AllocId>> {
+        Ok(ptr)
     }
 
     #[inline(always)]

compiler/rustc_const_eval/src/interpret/memory.rs

@@ -171,7 +171,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
             _ => {}
         }
         // And we need to get the provenance.
-        Ok(M::adjust_alloc_base_pointer(self, ptr))
+        M::adjust_alloc_base_pointer(self, ptr)
     }
 
     pub fn create_fn_alloc_ptr(
@@ -200,8 +200,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         kind: MemoryKind<M::MemoryKind>,
     ) -> InterpResult<'tcx, Pointer<M::Provenance>> {
         let alloc = Allocation::uninit(size, align, M::PANIC_ON_ALLOC_FAIL)?;
-        // We can `unwrap` since `alloc` contains no pointers.
-        Ok(self.allocate_raw_ptr(alloc, kind).unwrap())
+        self.allocate_raw_ptr(alloc, kind)
     }
 
     pub fn allocate_bytes_ptr(
@@ -210,10 +209,9 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         align: Align,
         kind: MemoryKind<M::MemoryKind>,
         mutability: Mutability,
-    ) -> Pointer<M::Provenance> {
+    ) -> InterpResult<'tcx, Pointer<M::Provenance>> {
         let alloc = Allocation::from_bytes(bytes, align, mutability);
-        // We can `unwrap` since `alloc` contains no pointers.
-        self.allocate_raw_ptr(alloc, kind).unwrap()
+        self.allocate_raw_ptr(alloc, kind)
     }
 
     /// This can fail only of `alloc` contains provenance.
@@ -230,7 +228,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         );
         let alloc = M::adjust_allocation(self, id, Cow::Owned(alloc), Some(kind))?;
         self.memory.alloc_map.insert(id, (kind, alloc.into_owned()));
-        Ok(M::adjust_alloc_base_pointer(self, Pointer::from(id)))
+        M::adjust_alloc_base_pointer(self, Pointer::from(id))
     }
 
     pub fn reallocate_ptr(

compiler/rustc_const_eval/src/interpret/place.rs

@@ -754,8 +754,8 @@ where
         str: &str,
         kind: MemoryKind<M::MemoryKind>,
         mutbl: Mutability,
-    ) -> MPlaceTy<'tcx, M::Provenance> {
-        let ptr = self.allocate_bytes_ptr(str.as_bytes(), Align::ONE, kind, mutbl);
+    ) -> InterpResult<'tcx, MPlaceTy<'tcx, M::Provenance>> {
+        let ptr = self.allocate_bytes_ptr(str.as_bytes(), Align::ONE, kind, mutbl)?;
         let meta = Scalar::from_machine_usize(u64::try_from(str.len()).unwrap(), self);
         let mplace = MemPlace { ptr: ptr.into(), meta: MemPlaceMeta::Meta(meta) };
 
@@ -764,7 +764,7 @@ where
             ty::TypeAndMut { ty: self.tcx.types.str_, mutbl },
         );
         let layout = self.layout_of(ty).unwrap();
-        MPlaceTy { mplace, layout, align: layout.align.abi }
+        Ok(MPlaceTy { mplace, layout, align: layout.align.abi })
     }
 
     /// Writes the aggregate to the destination.

compiler/rustc_middle/src/mir/interpret/error.rs

@@ -430,8 +430,10 @@ pub enum ResourceExhaustionInfo {
     ///
     /// The exact limit is set by the `const_eval_limit` attribute.
     StepLimitReached,
-    /// There is not enough memory to perform an allocation.
+    /// There is not enough memory (on the host) to perform an allocation.
     MemoryExhausted,
+    /// The address space (of the target) is full.
+    AddressSpaceFull,
 }
 
 impl fmt::Display for ResourceExhaustionInfo {
@@ -447,6 +449,9 @@ impl fmt::Display for ResourceExhaustionInfo {
             MemoryExhausted => {
                 write!(f, "tried to allocate more memory than available to compiler")
             }
+            AddressSpaceFull => {
+                write!(f, "there are no more free addresses in the address space")
+            }
         }
     }
 }

src/tools/miri/src/intptrcast.rs

@@ -162,11 +162,14 @@ impl<'mir, 'tcx> GlobalStateInner {
         Ok(Pointer::new(Some(Provenance::Wildcard), Size::from_bytes(addr)))
     }
 
-    fn alloc_base_addr(ecx: &MiriInterpCx<'mir, 'tcx>, alloc_id: AllocId) -> u64 {
+    fn alloc_base_addr(
+        ecx: &MiriInterpCx<'mir, 'tcx>,
+        alloc_id: AllocId,
+    ) -> InterpResult<'tcx, u64> {
         let mut global_state = ecx.machine.intptrcast.borrow_mut();
         let global_state = &mut *global_state;
 
-        match global_state.base_addr.entry(alloc_id) {
+        Ok(match global_state.base_addr.entry(alloc_id) {
             Entry::Occupied(entry) => *entry.get(),
             Entry::Vacant(entry) => {
                 // There is nothing wrong with a raw pointer being cast to an integer only after
@@ -181,7 +184,10 @@ impl<'mir, 'tcx> GlobalStateInner {
                     rng.gen_range(0..16)
                 };
                 // From next_base_addr + slack, round up to adjust for alignment.
-                let base_addr = global_state.next_base_addr.checked_add(slack).unwrap();
+                let base_addr = global_state
+                    .next_base_addr
+                    .checked_add(slack)
+                    .ok_or_else(|| err_exhaust!(AddressSpaceFull))?;
                 let base_addr = Self::align_addr(base_addr, align.bytes());
                 entry.insert(base_addr);
                 trace!(
@@ -197,24 +203,33 @@ impl<'mir, 'tcx> GlobalStateInner {
                 // of at least 1 to avoid two allocations having the same base address.
                 // (The logic in `alloc_id_from_addr` assumes unique addresses, and different
                 // function/vtable pointers need to be distinguishable!)
-                global_state.next_base_addr = base_addr.checked_add(max(size.bytes(), 1)).unwrap();
+                global_state.next_base_addr = base_addr
+                    .checked_add(max(size.bytes(), 1))
+                    .ok_or_else(|| err_exhaust!(AddressSpaceFull))?;
+                // Even if `Size` didn't overflow, we might still have filled up the address space.
+                if global_state.next_base_addr > ecx.machine_usize_max() {
+                    throw_exhaust!(AddressSpaceFull);
+                }
                 // Given that `next_base_addr` increases in each allocation, pushing the
                 // corresponding tuple keeps `int_to_ptr_map` sorted
                 global_state.int_to_ptr_map.push((base_addr, alloc_id));
 
                 base_addr
             }
-        }
+        })
     }
 
     /// Convert a relative (tcx) pointer to an absolute address.
-    pub fn rel_ptr_to_addr(ecx: &MiriInterpCx<'mir, 'tcx>, ptr: Pointer<AllocId>) -> u64 {
+    pub fn rel_ptr_to_addr(
+        ecx: &MiriInterpCx<'mir, 'tcx>,
+        ptr: Pointer<AllocId>,
+    ) -> InterpResult<'tcx, u64> {
         let (alloc_id, offset) = ptr.into_parts(); // offset is relative (AllocId provenance)
-        let base_addr = GlobalStateInner::alloc_base_addr(ecx, alloc_id);
+        let base_addr = GlobalStateInner::alloc_base_addr(ecx, alloc_id)?;
 
         // Add offset with the right kind of pointer-overflowing arithmetic.
         let dl = ecx.data_layout();
-        dl.overflowing_offset(base_addr, offset.bytes()).0
+        Ok(dl.overflowing_offset(base_addr, offset.bytes()).0)
     }
 
     /// When a pointer is used for a memory access, this computes where in which allocation the
@@ -232,7 +247,9 @@ impl<'mir, 'tcx> GlobalStateInner {
             GlobalStateInner::alloc_id_from_addr(ecx, addr.bytes())?
         };
 
-        let base_addr = GlobalStateInner::alloc_base_addr(ecx, alloc_id);
+        // This cannot fail: since we already have a pointer with that provenance, rel_ptr_to_addr
+        // must have been called in the past.
+        let base_addr = GlobalStateInner::alloc_base_addr(ecx, alloc_id).unwrap();
 
         // Wrapping "addr - base_addr"
         let dl = ecx.data_layout();

src/tools/miri/src/machine.rs

@@ -971,7 +971,7 @@ impl<'mir, 'tcx> Machine<'mir, 'tcx> for MiriMachine<'mir, 'tcx> {
     fn adjust_alloc_base_pointer(
         ecx: &MiriInterpCx<'mir, 'tcx>,
         ptr: Pointer<AllocId>,
-    ) -> Pointer<Provenance> {
+    ) -> InterpResult<'tcx, Pointer<Provenance>> {
         if cfg!(debug_assertions) {
             // The machine promises to never call us on thread-local or extern statics.
             let alloc_id = ptr.provenance;
@@ -985,17 +985,17 @@ impl<'mir, 'tcx> Machine<'mir, 'tcx> for MiriMachine<'mir, 'tcx> {
                 _ => {}
             }
         }
-        let absolute_addr = intptrcast::GlobalStateInner::rel_ptr_to_addr(ecx, ptr);
+        let absolute_addr = intptrcast::GlobalStateInner::rel_ptr_to_addr(ecx, ptr)?;
         let tag = if let Some(borrow_tracker) = &ecx.machine.borrow_tracker {
             borrow_tracker.borrow_mut().base_ptr_tag(ptr.provenance, &ecx.machine)
         } else {
             // Value does not matter, SB is disabled
             BorTag::default()
         };
-        Pointer::new(
+        Ok(Pointer::new(
             Provenance::Concrete { alloc_id: ptr.provenance, tag },
             Size::from_bytes(absolute_addr),
-        )
+        ))
     }
 
     #[inline(always)]

src/tools/miri/src/shims/backtrace.rs

@@ -190,9 +190,9 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
             0 => {
                 // These are "mutable" allocations as we consider them to be owned by the callee.
                 let name_alloc =
-                    this.allocate_str(&name, MiriMemoryKind::Rust.into(), Mutability::Mut);
+                    this.allocate_str(&name, MiriMemoryKind::Rust.into(), Mutability::Mut)?;
                 let filename_alloc =
-                    this.allocate_str(&filename, MiriMemoryKind::Rust.into(), Mutability::Mut);
+                    this.allocate_str(&filename, MiriMemoryKind::Rust.into(), Mutability::Mut)?;
 
                 this.write_immediate(
                     name_alloc.to_ref(this),

src/tools/miri/src/shims/panic.rs

@@ -172,7 +172,7 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
         let this = self.eval_context_mut();
 
         // First arg: message.
-        let msg = this.allocate_str(msg, MiriMemoryKind::Machine.into(), Mutability::Not);
+        let msg = this.allocate_str(msg, MiriMemoryKind::Machine.into(), Mutability::Not)?;
 
         // Call the lang item.
         let panic = this.tcx.lang_items().panic_fn().unwrap();