From 9c3442c0938127788fa59e4ceb80ae78b86fad1d Mon Sep 17 00:00:00 2001 From: Dong-hee Na Date: Sun, 23 Apr 2023 11:18:49 -0600 Subject: [PATCH] gh-101408: PyObject_GC_Resize should calculate preheader size. (gh-101741) --- .../2023-02-09-23-09-29.gh-issue-101408._paFIF.rst | 2 ++ Modules/gcmodule.c | 13 +++++++------ 2 files changed, 9 insertions(+), 6 deletions(-) create mode 100644 Misc/NEWS.d/next/C API/2023-02-09-23-09-29.gh-issue-101408._paFIF.rst diff --git a/Misc/NEWS.d/next/C API/2023-02-09-23-09-29.gh-issue-101408._paFIF.rst b/Misc/NEWS.d/next/C API/2023-02-09-23-09-29.gh-issue-101408._paFIF.rst new file mode 100644 index 00000000000..172d66163d4 --- /dev/null +++ b/Misc/NEWS.d/next/C API/2023-02-09-23-09-29.gh-issue-101408._paFIF.rst @@ -0,0 +1,2 @@ +:c:func:`PyObject_GC_Resize` should calculate preheader size if needed. +Patch by Dong-hee Na. diff --git a/Modules/gcmodule.c b/Modules/gcmodule.c index 1d00fc3e717..966c1e61550 100644 --- a/Modules/gcmodule.c +++ b/Modules/gcmodule.c @@ -2361,16 +2361,17 @@ PyVarObject * _PyObject_GC_Resize(PyVarObject *op, Py_ssize_t nitems) { const size_t basicsize = _PyObject_VAR_SIZE(Py_TYPE(op), nitems); + const size_t presize = _PyType_PreHeaderSize(((PyObject *)op)->ob_type); _PyObject_ASSERT((PyObject *)op, !_PyObject_GC_IS_TRACKED(op)); - if (basicsize > (size_t)PY_SSIZE_T_MAX - sizeof(PyGC_Head)) { + if (basicsize > (size_t)PY_SSIZE_T_MAX - presize) { return (PyVarObject *)PyErr_NoMemory(); } - - PyGC_Head *g = AS_GC(op); - g = (PyGC_Head *)PyObject_Realloc(g, sizeof(PyGC_Head) + basicsize); - if (g == NULL) + char *mem = (char *)op - presize; + mem = (char *)PyObject_Realloc(mem, presize + basicsize); + if (mem == NULL) { return (PyVarObject *)PyErr_NoMemory(); - op = (PyVarObject *) FROM_GC(g); + } + op = (PyVarObject *) (mem + presize); Py_SET_SIZE(op, nitems); return op; }