[clang] a13f036 - [clang][Interp] Check one-past-the-end pointers in GetPtrField

[Timm Bäder via cfe-commits]

Author: Timm Bäder
Date: 2023-09-05T11:00:40+02:00
New Revision: a13f036949b05e5f9d1ac1e33fed465c939aca62

URL: https://github.com/llvm/llvm-project/commit/a13f036949b05e5f9d1ac1e33fed465c939aca62
DIFF: https://github.com/llvm/llvm-project/commit/a13f036949b05e5f9d1ac1e33fed465c939aca62.diff

LOG: [clang][Interp] Check one-past-the-end pointers in GetPtrField

Rename CheckBaseDerived to something more general and call it in
GetPtrField() as well, so we don't crash later in Pointer::toAPValue().

Differential Revision: https://reviews.llvm.org/D149149

Added: 
    

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

Removed: 
    


################################################################################
diff  --git a/clang/lib/AST/Interp/Interp.cpp b/clang/lib/AST/Interp/Interp.cpp
index 23c54b3898e102..719a96daaebdd7 100644
--- a/clang/lib/AST/Interp/Interp.cpp
+++ b/clang/lib/AST/Interp/Interp.cpp
@@ -213,8 +213,8 @@ bool CheckRange(InterpState &S, CodePtr OpPC, const Pointer &Ptr,
   return false;
 }
 
-bool CheckBaseDerived(InterpState &S, CodePtr OpPC, const Pointer &Ptr,
-                      CheckSubobjectKind CSK) {
+bool CheckSubobject(InterpState &S, CodePtr OpPC, const Pointer &Ptr,
+                    CheckSubobjectKind CSK) {
   if (!Ptr.isOnePastEnd())
     return true;
 

diff  --git a/clang/lib/AST/Interp/Interp.h b/clang/lib/AST/Interp/Interp.h
index 006abc0f0e94ac..b87a5c1cbd0e48 100644
--- a/clang/lib/AST/Interp/Interp.h
+++ b/clang/lib/AST/Interp/Interp.h
@@ -67,9 +67,9 @@ bool CheckRange(InterpState &S, CodePtr OpPC, const Pointer &Ptr,
 bool CheckRange(InterpState &S, CodePtr OpPC, const Pointer &Ptr,
                 CheckSubobjectKind CSK);
 
-/// Checks if accessing a base or derived record of the given pointer is valid.
-bool CheckBaseDerived(InterpState &S, CodePtr OpPC, const Pointer &Ptr,
-                      CheckSubobjectKind CSK);
+/// Checks if Ptr is a one-past-the-end pointer.
+bool CheckSubobject(InterpState &S, CodePtr OpPC, const Pointer &Ptr,
+                    CheckSubobjectKind CSK);
 
 /// Checks if a pointer points to const storage.
 bool CheckConst(InterpState &S, CodePtr OpPC, const Pointer &Ptr);
@@ -1121,6 +1121,9 @@ inline bool GetPtrField(InterpState &S, CodePtr OpPC, uint32_t Off) {
     return false;
   if (!CheckRange(S, OpPC, Ptr, CSK_Field))
     return false;
+  if (!CheckSubobject(S, OpPC, Ptr, CSK_Field))
+    return false;
+
   S.Stk.push<Pointer>(Ptr.atField(Off));
   return true;
 }
@@ -1165,7 +1168,7 @@ inline bool GetPtrDerivedPop(InterpState &S, CodePtr OpPC, uint32_t Off) {
   const Pointer &Ptr = S.Stk.pop<Pointer>();
   if (!CheckNull(S, OpPC, Ptr, CSK_Derived))
     return false;
-  if (!CheckBaseDerived(S, OpPC, Ptr, CSK_Derived))
+  if (!CheckSubobject(S, OpPC, Ptr, CSK_Derived))
     return false;
   S.Stk.push<Pointer>(Ptr.atFieldSub(Off));
   return true;
@@ -1175,7 +1178,7 @@ inline bool GetPtrBase(InterpState &S, CodePtr OpPC, uint32_t Off) {
   const Pointer &Ptr = S.Stk.peek<Pointer>();
   if (!CheckNull(S, OpPC, Ptr, CSK_Base))
     return false;
-  if (!CheckBaseDerived(S, OpPC, Ptr, CSK_Base))
+  if (!CheckSubobject(S, OpPC, Ptr, CSK_Base))
     return false;
   S.Stk.push<Pointer>(Ptr.atField(Off));
   return true;
@@ -1185,7 +1188,7 @@ inline bool GetPtrBasePop(InterpState &S, CodePtr OpPC, uint32_t Off) {
   const Pointer &Ptr = S.Stk.pop<Pointer>();
   if (!CheckNull(S, OpPC, Ptr, CSK_Base))
     return false;
-  if (!CheckBaseDerived(S, OpPC, Ptr, CSK_Base))
+  if (!CheckSubobject(S, OpPC, Ptr, CSK_Base))
     return false;
   S.Stk.push<Pointer>(Ptr.atField(Off));
   return true;

diff  --git a/clang/test/AST/Interp/records.cpp b/clang/test/AST/Interp/records.cpp
index b559f1f8b95b0a..2b79ec8be0311d 100644
--- a/clang/test/AST/Interp/records.cpp
+++ b/clang/test/AST/Interp/records.cpp
@@ -531,6 +531,29 @@ namespace DeclRefs {
   //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;
+
+#if 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}}
+
+#endif
+  constexpr const int *pn = &(&b + 1)->n; // expected-error {{must be initialized by a constant expression}} \
+                                          // expected-note {{cannot access field of pointer past the end of object}} \
+                                          // ref-error {{must be initialized by a constant expression}} \
+                                          // ref-note {{cannot access field of pointer past the end of object}}
+
+}
+
 #if __cplusplus >= 202002L
 namespace VirtualCalls {
 namespace Obvious {