https://github.com/python/cpython/commit/58c44c2bf2e6d251548652a21d9ee27265ee6dea commit: 58c44c2bf2e6d251548652a21d9ee27265ee6dea branch: main author: Kumar Aditya <[email protected]> committer: kumaraditya303 <[email protected]> date: 2025-10-18T16:36:58+05:30 summary:
gh-140067: Fix memory leak in sub-interpreter creation (#140111) (#140261) Fix memory leak in sub-interpreter creation caused by overwriting of the previously used `_malloced` field. Now the pointer is stored in the first word of the memory block to avoid it being overwritten accidentally. Co-authored-by: Kumar Aditya <[email protected]> files: A Misc/NEWS.d/next/Core_and_Builtins/2025-10-14-17-07-37.gh-issue-140067.ID2gOm.rst M Include/internal/pycore_interp_structs.h M Lib/test/test_threading.py M Python/pystate.c diff --git a/Include/internal/pycore_interp_structs.h b/Include/internal/pycore_interp_structs.h index 2124e76514f1af..badc97808c6132 100644 --- a/Include/internal/pycore_interp_structs.h +++ b/Include/internal/pycore_interp_structs.h @@ -769,12 +769,6 @@ struct _is { * and should be placed at the beginning. */ struct _ceval_state ceval; - /* This structure is carefully allocated so that it's correctly aligned - * to avoid undefined behaviors during LOAD and STORE. The '_malloced' - * field stores the allocated pointer address that will later be freed. - */ - void *_malloced; - PyInterpreterState *next; int64_t id; diff --git a/Lib/test/test_threading.py b/Lib/test/test_threading.py index d0f0e8ab2f7724..efd69a1f4fe468 100644 --- a/Lib/test/test_threading.py +++ b/Lib/test/test_threading.py @@ -1776,6 +1776,7 @@ def task(): self.assertEqual(os.read(r_interp, 1), DONE) @cpython_only + @support.skip_if_sanitizer(thread=True, memory=True) def test_daemon_threads_fatal_error(self): import_module("_testcapi") subinterp_code = f"""if 1: diff --git a/Misc/NEWS.d/next/Core_and_Builtins/2025-10-14-17-07-37.gh-issue-140067.ID2gOm.rst b/Misc/NEWS.d/next/Core_and_Builtins/2025-10-14-17-07-37.gh-issue-140067.ID2gOm.rst new file mode 100644 index 00000000000000..3c5a828101d9a8 --- /dev/null +++ b/Misc/NEWS.d/next/Core_and_Builtins/2025-10-14-17-07-37.gh-issue-140067.ID2gOm.rst @@ -0,0 +1 @@ +Fix memory leak in sub-interpreter creation. diff --git a/Python/pystate.c b/Python/pystate.c index c402d89a16145b..af7828d6a030ab 100644 --- a/Python/pystate.c +++ b/Python/pystate.c @@ -457,16 +457,19 @@ _PyInterpreterState_Enable(_PyRuntimeState *runtime) static PyInterpreterState * alloc_interpreter(void) { + // Aligned allocation for PyInterpreterState. + // the first word of the memory block is used to store + // the original pointer to be used later to free the memory. size_t alignment = _Alignof(PyInterpreterState); - size_t allocsize = sizeof(PyInterpreterState) + alignment - 1; + size_t allocsize = sizeof(PyInterpreterState) + sizeof(void *) + alignment - 1; void *mem = PyMem_RawCalloc(1, allocsize); if (mem == NULL) { return NULL; } - PyInterpreterState *interp = _Py_ALIGN_UP(mem, alignment); - assert(_Py_IS_ALIGNED(interp, alignment)); - interp->_malloced = mem; - return interp; + void *ptr = _Py_ALIGN_UP((char *)mem + sizeof(void *), alignment); + ((void **)ptr)[-1] = mem; + assert(_Py_IS_ALIGNED(ptr, alignment)); + return ptr; } static void @@ -481,7 +484,7 @@ free_interpreter(PyInterpreterState *interp) interp->obmalloc = NULL; } assert(_Py_IS_ALIGNED(interp, _Alignof(PyInterpreterState))); - PyMem_RawFree(interp->_malloced); + PyMem_RawFree(((void **)interp)[-1]); } } _______________________________________________ Python-checkins mailing list -- [email protected] To unsubscribe send an email to [email protected] https://mail.python.org/mailman3//lists/python-checkins.python.org Member address: [email protected]
