[PATCH] D149013: [clang][Interp] Check pointers when accessing base class

[Timm Bäder via Phabricator via cfe-commits]

tbaeder created this revision.
tbaeder added reviewers: aaron.ballman, erichkeane, tahonermann, shafik.
Herald added a project: All.
tbaeder requested review of this revision.
Herald added a project: clang.
Herald added a subscriber: cfe-commits.

Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D149013

Files:
  clang/lib/AST/Interp/Interp.cpp
  clang/lib/AST/Interp/Interp.h
  clang/test/AST/Interp/records.cpp


Index: clang/test/AST/Interp/records.cpp
===================================================================
--- clang/test/AST/Interp/records.cpp
+++ clang/test/AST/Interp/records.cpp
@@ -497,6 +497,21 @@
   //static_assert(b.a.f == 100, "");
 }
 
+namespace PointerArith {
+  struct A {};
+  struct B : A { int n; };
+
+  B b = {};
+  constexpr A *a1 = &b;
+  constexpr B *b1 = &b + 1;
+  constexpr B *b2 = &b + 0;
+
+  constexpr A *a2 = &b + 1; // expected-error {{must be initialized by a constant expression}} \
+                            // expected-note {{cannot access base class of pointer past the end of object}} \
+                            // ref-error {{must be initialized by a constant expression}} \
+                            // ref-note {{cannot access base class of pointer past the end of object}}
+}
+
 #if __cplusplus >= 202002L
 namespace VirtualCalls {
 namespace Obvious {
Index: clang/lib/AST/Interp/Interp.h
===================================================================
--- clang/lib/AST/Interp/Interp.h
+++ clang/lib/AST/Interp/Interp.h
@@ -67,6 +67,9 @@
 bool CheckRange(InterpState &S, CodePtr OpPC, const Pointer &Ptr,
                 CheckSubobjectKind CSK);
 
+/// Checks if accessing a base of the given pointer is valid.
+bool CheckBase(InterpState &S, CodePtr OpPC, const Pointer &Ptr);
+
 /// Checks if a pointer points to const storage.
 bool CheckConst(InterpState &S, CodePtr OpPC, const Pointer &Ptr);
 
@@ -1079,6 +1082,8 @@
   const Pointer &Ptr = S.Stk.peek<Pointer>();
   if (!CheckNull(S, OpPC, Ptr, CSK_Base))
     return false;
+  if (!CheckBase(S, OpPC, Ptr))
+    return false;
   S.Stk.push<Pointer>(Ptr.atField(Off));
   return true;
 }
@@ -1087,6 +1092,8 @@
   const Pointer &Ptr = S.Stk.pop<Pointer>();
   if (!CheckNull(S, OpPC, Ptr, CSK_Base))
     return false;
+  if (!CheckBase(S, OpPC, Ptr))
+    return false;
   S.Stk.push<Pointer>(Ptr.atField(Off));
   return true;
 }
Index: clang/lib/AST/Interp/Interp.cpp
===================================================================
--- clang/lib/AST/Interp/Interp.cpp
+++ clang/lib/AST/Interp/Interp.cpp
@@ -211,6 +211,15 @@
   return false;
 }
 
+bool CheckBase(InterpState &S, CodePtr OpPC, const Pointer &Ptr) {
+  if (!Ptr.isOnePastEnd())
+    return true;
+
+  const SourceInfo &Loc = S.Current->getSource(OpPC);
+  S.FFDiag(Loc, diag::note_constexpr_past_end_subobject) << CSK_Base;
+  return false;
+}
+
 bool CheckConst(InterpState &S, CodePtr OpPC, const Pointer &Ptr) {
   assert(Ptr.isLive() && "Pointer is not live");
   if (!Ptr.isConst())


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D149013.516130.patch
Type: text/x-patch
Size: 2574 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/cfe-commits/attachments/20230423/73b74eaf/attachment-0001.bin>