Fix dangling pointer in internals::registered_types_cpp_fast from #5842 #5867
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
…ind#5842 @oremanj pointed out in a comment on pybind#5842 that I missed part of the nanobind PR I was porting in such a way that we could have dangling pointers in internals::registered_types_cpp_fast. This PR adds a test that reproed the bug and then fixes the test.
oremanj
reviewed
Oct 14, 2025
include/pybind11/detail/internals.h
Outdated
Comment on lines
340
to
341
| // keys (the type_info from each DSO) mapped to the same | ||
| // type_info*. We need to keep track of these aliases so that we clean |
There was a problem hiding this comment.
Suggested change
| // keys (the type_info from each DSO) mapped to the same | |
| // type_info*. We need to keep track of these aliases so that we clean | |
| // keys (the std::type_info from each DSO) mapped to the same | |
| // detail::type_info*. We need to keep track of these aliases so that we clean |
Suggest disambiguating since both the key and value types are something::type_info
include/pybind11/detail/internals.h
Outdated
| // nb_alias_chain` added in | ||
| // https://github.com/wjakob/nanobind/commit/b515b1f7f2f4ecc0357818e6201c94a9f4cbfdc2 | ||
| #if PYBIND11_INTERNALS_VERSION >= 12 | ||
| struct alias_chain_entry { |
There was a problem hiding this comment.
You can use std::forward_list instead of rolling your own singly linked list. nanobind goes to a lot of trouble to avoid anything from the STL, while pybind11 already has other uses of forward_list and it is basically the same thing you wrote here.
There was a problem hiding this comment.
TIL sizeof(std::forward_list) == 8 and it's in C++11, SGTM
| def test_cross_module_use_after_one_module_dealloc(): | ||
| # This is a regression test for a bug that occurred during development of | ||
| # internals::registered_types_cpp_fast (see #5842). registered_types_cpp_fast maps | ||
| # &typeid(T) to a raw non-owning pointer to a Python metaclass. If two DSOs both |
There was a problem hiding this comment.
These are just Python classes (types), not metaclasses (their instances are not types). I might say "type object pointer" to disambiguate from the std::type_info pointer.
oremanj
reviewed
Oct 14, 2025
| struct UnrelatedClass {}; | ||
|
|
||
| TEST_SUBMODULE(class_cross_module_use_after_one_module_dealloc, m) { | ||
| m.def("register_and_instantiate_cross_dso_class", [](py::module_ m) { |
There was a problem hiding this comment.
Suggested change
| m.def("register_and_instantiate_cross_dso_class", [](py::module_ m) { | |
| m.def("register_and_instantiate_cross_dso_class", [](const py::module_ &m) { |
| return CrossDSOClass(); | ||
| }); | ||
| m.def("register_unrelated_class", | ||
| [](py::module_ m) { py::class_<UnrelatedClass>(m, "UnrelatedClass"); }); |
There was a problem hiding this comment.
Suggested change
| [](py::module_ m) { py::class_<UnrelatedClass>(m, "UnrelatedClass"); }); | |
| [](const py::module_ &m) { py::class_<UnrelatedClass>(m, "UnrelatedClass"); }); |
| m.def("missing_header_return", []() { return std::vector<float>(); }); | ||
|
|
||
| // test_class_cross_module_use_after_one_module_dealloc | ||
| m.def("consume_cross_dso_class", [](CrossDSOClass) {}); |
There was a problem hiding this comment.
Suggested change
| m.def("consume_cross_dso_class", [](CrossDSOClass) {}); | |
| m.def("consume_cross_dso_class", [](const CrossDSOClass &) {}); |
oremanj
reviewed
Oct 14, 2025
oremanj
reviewed
Oct 14, 2025
oremanj
reviewed
Oct 14, 2025
|
Thanks for fixing things up @oremanj! Was out today, planned to get to it tomorrow |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
2 participants
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Description
@oremanj pointed out in a comment on #5842 that I missed part of the nanobind PR I was porting in such a way that we could have dangling pointers in internals::registered_types_cpp_fast. This PR adds a test that reproed the bug and then fixes the test.