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properly track why we checked whether a pointer is in-bounds

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also simplify the in-bounds checking in Miri's borrow trackers
This commit is contained in:
Ralf Jung
2023-08-01 17:03:19 +02:00
parent 7d5886504c
commit 8496292dda
44 changed files with 130 additions and 122 deletions
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23
compiler/rustc_const_eval/src/interpret/memory.rs
View File

@@ -317,7 +317,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
kind = "static_mem"
)
}
None => err_ub!(PointerUseAfterFree(alloc_id)),
None => err_ub!(PointerUseAfterFree(alloc_id, CheckInAllocMsg::MemoryAccessTest)),
}
.into());
};
@@ -380,7 +380,8 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
M::enforce_alignment(self),
CheckInAllocMsg::MemoryAccessTest,
|alloc_id, offset, prov| {
let (size, align) = self.get_live_alloc_size_and_align(alloc_id)?;
let (size, align) = self
.get_live_alloc_size_and_align(alloc_id, CheckInAllocMsg::MemoryAccessTest)?;
Ok((size, align, (alloc_id, offset, prov)))
},
)
@@ -404,7 +405,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
CheckAlignment::Error,
msg,
|alloc_id, _, _| {
let (size, align) = self.get_live_alloc_size_and_align(alloc_id)?;
let (size, align) = self.get_live_alloc_size_and_align(alloc_id, msg)?;
Ok((size, align, ()))
},
)?;
@@ -414,7 +415,9 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
/// Low-level helper function to check if a ptr is in-bounds and potentially return a reference
/// to the allocation it points to. Supports both shared and mutable references, as the actual
/// checking is offloaded to a helper closure. `align` defines whether and which alignment check
/// is done. Returns `None` for size 0, and otherwise `Some` of what `alloc_size` returned.
/// is done.
///
/// If this returns `None`, the size is 0; it can however return `Some` even for size 0.
fn check_and_deref_ptr<T>(
&self,
ptr: Pointer<Option<M::Provenance>>,
@@ -515,7 +518,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
}
Some(GlobalAlloc::Function(..)) => throw_ub!(DerefFunctionPointer(id)),
Some(GlobalAlloc::VTable(..)) => throw_ub!(DerefVTablePointer(id)),
None => throw_ub!(PointerUseAfterFree(id)),
None => throw_ub!(PointerUseAfterFree(id, CheckInAllocMsg::MemoryAccessTest)),
Some(GlobalAlloc::Static(def_id)) => {
assert!(self.tcx.is_static(def_id));
assert!(!self.tcx.is_thread_local_static(def_id));
@@ -761,11 +764,15 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
}
}
/// Obtain the size and alignment of a live allocation.
pub fn get_live_alloc_size_and_align(&self, id: AllocId) -> InterpResult<'tcx, (Size, Align)> {
/// Obtain the size and alignment of a *live* allocation.
fn get_live_alloc_size_and_align(
&self,
id: AllocId,
msg: CheckInAllocMsg,
) -> InterpResult<'tcx, (Size, Align)> {
let (size, align, kind) = self.get_alloc_info(id);
if matches!(kind, AllocKind::Dead) {
throw_ub!(PointerUseAfterFree(id))
throw_ub!(PointerUseAfterFree(id, msg))
}
Ok((size, align))
}

3
compiler/rustc_const_eval/src/interpret/step.rs
View File

@@ -224,8 +224,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
Len(place) => {
let src = self.eval_place(place)?;
let op = self.place_to_op(&src)?;
let len = op.len(self)?;
let len = src.len(self)?;
self.write_scalar(Scalar::from_target_usize(len, self), &dest)?;
}