Rollup merge of #130342 - RalfJung:slice-idx-overflow, r=saethlin

interpret, miri: fix dealing with overflow during slice indexing and allocation

This is mostly to fix https://github.com/rust-lang/rust/issues/130284.

I then realized we're using somewhat sketchy arguments for a similar multiplication in `copy`/`copy_nonoverlapping`/`write_bytes`,  so I made them all share the same function that checks exactly the right thing. (The intrinsics would previously fail on allocations larger than `1 << 47` bytes... which are theoretically possible maybe? Anyway it seems conceptually wrong to use any other bound than `isize::MAX` here.)

1 files changed, 4 insertions, 3 deletions

diff --git a/compiler/rustc_const_eval/src/interpret/memory.rs b/compiler/rustc_const_eval/src/interpret/memory.rs
index 2ad675025a2..b1d1dab7c16 100644
--- a/compiler/rustc_const_eval/src/interpret/memory.rs
+++ b/compiler/rustc_const_eval/src/interpret/memory.rs
@@ -222,7 +222,7 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
         } else {
             Allocation::try_uninit(size, align)?
         };
-        self.allocate_raw_ptr(alloc, kind)
+        self.insert_allocation(alloc, kind)
     }
 
     pub fn allocate_bytes_ptr(
@@ -233,14 +233,15 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
         mutability: Mutability,
     ) -> InterpResult<'tcx, Pointer<M::Provenance>> {
         let alloc = Allocation::from_bytes(bytes, align, mutability);
-        self.allocate_raw_ptr(alloc, kind)
+        self.insert_allocation(alloc, kind)
     }
 
-    pub fn allocate_raw_ptr(
+    pub fn insert_allocation(
         &mut self,
         alloc: Allocation<M::Provenance, (), M::Bytes>,
         kind: MemoryKind<M::MemoryKind>,
     ) -> InterpResult<'tcx, Pointer<M::Provenance>> {
+        assert!(alloc.size() <= self.max_size_of_val());
         let id = self.tcx.reserve_alloc_id();
         debug_assert_ne!(
             Some(kind),