Merge pull request #10605 from harisibrar1/fix/rtti-ambiguous-private-base

fix(libc): reject a catch or upcast to a base that a private path repeats

core/libs/prx/libc/src/exception/Runtime.cpp

@@ -202,12 +202,15 @@ void VisitBases(const std::type_info* type, BaseLocation location, bool publicPa
 
 void Bases(const std::type_info* type, void* object, Search& search) {
     std::uintptr_t identity = 0;
+    bool reachedPublicly = false;
     auto visitor = [&](const std::type_info* candidate, BaseLocation location, bool publicPath) {
-        if (!publicPath || !Equal(candidate, search.wanted)) return;
-        if (!search.count) { search.found = location.object; identity = location.identity; search.count = 1; }
+        if (!Equal(candidate, search.wanted)) return;
+        if (!search.count) { search.found = location.object; identity = location.identity; search.count = 1; reachedPublicly = publicPath; }
         else if (search.found != location.object || identity != location.identity) search.count = 2;
+        else if (publicPath) reachedPublicly = true;
     };
     VisitBases(type, {object, 0}, true, visitor);
+    if (search.count == 1 && !reachedPublicly) search.count = 0;
 }
 
 bool PointerMatch(const __cxxabiv1::__pbase_type_info* caught, const __cxxabiv1::__pbase_type_info* thrown,

core/libs/tests/ExceptionRuntime.cpp

@@ -40,6 +40,7 @@ struct Virtual : virtual Base {};
 struct Left : Base {};
 struct Right : Base {};
 struct Repeated : Left, Right {};
+struct MixedRepeated : Left, private Right {};
 struct LeftVirtual : virtual Base {};
 struct RightVirtual : virtual Base {};
 struct Diamond : LeftVirtual, RightVirtual {};
@@ -59,6 +60,9 @@ void CheckRtti() {
     try { throw static_cast<Repeated*>(nullptr); }
     catch (Base*) { assert(false); }
     catch (Repeated* p) { assert(p == nullptr); }
+    try { throw MixedRepeated(); }
+    catch (Base&) { assert(false); }
+    catch (MixedRepeated&) {}
     try { throw static_cast<Diamond*>(nullptr); }
     catch (Base* p) { assert(p == nullptr); }
     try { throw nullptr; }

core/libs/tests/WindowsExceptions.cpp

@@ -56,6 +56,17 @@ static void TestTypeInfoVtables() {
     if (!upcastType(&multiple, &base, &object) || object != storage.data() + 16) throw std::runtime_error("multiple RTTI upcast failed");
     object = storage.data();
     if (catchType(&other, &single, &object, 0)) throw std::runtime_error("unrelated RTTI catch succeeded");
+    TypeRecord shared {classTable + 2 * sizeof(void*), "6Shared"};
+    SingleRecord publicPath {{singleTable + 2 * sizeof(void*), "10PublicPath"}, &shared};
+    SingleRecord privatePath {{singleTable + 2 * sizeof(void*), "11PrivatePath"}, &shared};
+    MultipleRecord mixed {{multipleTable + 2 * sizeof(void*), "5Mixed"}, 1, 2, {{&publicPath.type, 2}, {&privatePath.type, 16 << 8}}};
+    MultipleRecord hidden {{multipleTable + 2 * sizeof(void*), "6Hidden"}, 0, 1, {{&privatePath.type, 0}, {}}};
+    object = storage.data();
+    if (catchType(&shared, &mixed, &object, 0) || object != storage.data()) throw std::runtime_error("RTTI catch of a base repeated through a private path succeeded");
+    if (upcastType(&mixed, &shared, &object) || object != storage.data()) throw std::runtime_error("RTTI upcast to a base repeated through a private path succeeded");
+    if (!catchType(&publicPath, &mixed, &object, 0) || object != storage.data()) throw std::runtime_error("RTTI catch of the public path failed");
+    object = storage.data();
+    if (catchType(&shared, &hidden, &object, 0)) throw std::runtime_error("RTTI catch of a privately inherited base succeeded");
 }
 
 extern "C" [[noreturn]] void NotImplemented_nid_no_patch(const char*);