Hello folks! Just the other day, we run into a problem in our C++ project, which we tracked down to static initialization order fiasco. Specifically, we have a global variable/constant container, which includes elements that have a proto object container a map. https://godbolt.org/z/49Mx6h7Yz
What happened is that the global variable "store_t::m_map" is initialized first. The stack trace shows that the code in protobuf UntypedMapBase::TableEntryIsNonEmptyList() gets executed. ==275==ERROR: ThreadSanitizer: SEGV on unknown address 0x0001c8c56070 (pc 0x7f347b67db2a bp 0x7ffdd006baf0 sp 0x7ffdd006ba90 T275) ==275==The signal is caused by a READ memory access. #0 google::protobuf::internal::UntypedMapBase::TableEntryIsNonEmptyList(unsigned long) const bazel-out/k8-dbg/bin/external/com_google_protobuf/src/google/protobuf/_virtual_includes/protobuf_lite/google/protobuf/map.h:514 #1 google::protobuf::internal::UntypedMapBase::NodeAndBucket google::protobuf::internal::KeyMapBase<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >::FindHelper<char const*>(char const* const&, absl::container_internal::btree_iterator<absl::container_internal::btree_node<absl::container_internal::map_params<std::reference_wrapper<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const>, google::protobuf::internal::NodeBase*, google::protobuf::internal::TransparentSupport<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >::less, google::protobuf::internal::MapAllocator<std::pair<std::reference_wrapper<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const> const, google::protobuf::internal::NodeBase*> >, 256, false> >, std::pair<std::reference_wrapper<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const> const, google::protobuf::internal::NodeBase*>&, std::pair<std::reference_wrapper<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const> const, google::protobuf::internal::NodeBase*>*>*) const bazel-out/k8-dbg/bin/external/com_google_protobuf/src/google/protobuf/_virtual_includes/protobuf_lite/google/protobuf/map.h:767 #2 std::pair<google::protobuf::Map<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, md::redundancyType>::iterator, bool> google::protobuf::Map<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, md::redundancyType>::TryEmplaceInternal<char const* const&>(char const* const&) bazel-out/k8-dbg/bin/external/com_google_protobuf/src/google/protobuf/_virtual_includes/protobuf_lite/google/protobuf/map.h:1463 #3 std::pair<google::protobuf::Map<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, md::redundancyType>::iterator, bool> google::protobuf::Map<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, md::redundancyType>::ArenaAwareTryEmplace<char const* const&>(std::integral_constant<bool, false>, char const* const&) bazel-out/k8-dbg/bin/external/com_google_protobuf/src/google/protobuf/_virtual_includes/protobuf_lite/google/protobuf/map.h:1532 #4 std::pair<google::protobuf::Map<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, md::redundancyType>::iterator, bool> google::protobuf::Map<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, md::redundancyType>::try_emplace<char const* const&>(char const* const&) bazel-out/k8-dbg/bin/external/com_google_protobuf/src/google/protobuf/_virtual_includes/protobuf_lite/google/protobuf/map.h:1300 #5 md::redundancyType& google::protobuf::Map<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, md::redundancyType>::operator[]<char const*>(char const* const&) bazel-out/k8-dbg/bin/external/com_google_protobuf/src/google/protobuf/_virtual_includes/protobuf_lite/google/protobuf/map.h:1222 #6 info_t::constructTI() src/info.cpp:62 #7 info_t::info_t(int) src/info.cpp:23 #8 __static_initialization_and_destruction_0 store.cpp:37 This sigsegv happens if "kGlobalEmptyTable" in protobuf/map.cc was not yet initialized and an invalid pointer is dereferenced in UntypedMapBase::TableEntryIsNonEmptyList(). I'd like to submit a patch that move the global variable definition inside a function, i.e.a a block-scope variable with static storage duration. I'd also use an std::array to define "kGlobalEmptyTable". Are there any concerns with doing this? Regards, Knut Stolze -- You received this message because you are subscribed to the Google Groups "Protocol Buffers" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/protobuf/b63ec52c-059d-442b-9b17-061f3da469a1n%40googlegroups.com.
