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GH-111784: Fix segfault by keeping pyexpat module alive for capsule lifetime #112104

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GH-111784: Fix segfault by keeping pyexpat module alive for capsule lifetime #112104

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5afa266
keep pyexpat module alive for capsule
kumaraditya303 Nov 15, 2023
7583609
📜🤖 Added by blurb_it.
blurb-it[bot] Nov 15, 2023
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1 change: 1 addition & 0 deletions Misc/NEWS.d/next/Library/2023-11-15-04-44-28.gh-issue-111784._ZyckQ.rst
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Original file line number Diff line number Diff line change
@@ -0,0 +1 @@
Fix segfault during deallocation of ``_elementtree.XMLParser`` by keeping pyexpat module alive for capsule lifetime. Patch by Kumar Aditya.
11 changes: 9 additions & 2 deletions Modules/_elementtree.c
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Expand Up @@ -98,6 +98,8 @@ typedef struct {
PyTypeObject *TreeBuilder_Type;
PyTypeObject *XMLParser_Type;

/* Strong ref for capsule */
PyObject *expat_capsule;
struct PyExpat_CAPI *expat_capi;
} elementtreestate;

Expand Down Expand Up @@ -155,7 +157,7 @@ elementtree_clear(PyObject *m)
Py_CLEAR(st->ElementIter_Type);
Py_CLEAR(st->TreeBuilder_Type);
Py_CLEAR(st->XMLParser_Type);

Py_CLEAR(st->expat_capsule);
st->expat_capi = NULL;
return 0;
}
Expand All @@ -169,6 +171,7 @@ elementtree_traverse(PyObject *m, visitproc visit, void *arg)
Py_VISIT(st->elementpath_obj);
Py_VISIT(st->comment_factory);
Py_VISIT(st->pi_factory);
Py_VISIT(st->expat_capsule);

// Heap types
Py_VISIT(st->Element_Type);
Expand Down Expand Up @@ -4343,7 +4346,11 @@ module_exec(PyObject *m)
goto error;

/* link against pyexpat */
st->expat_capi = PyCapsule_Import(PyExpat_CAPSULE_NAME, 0);
st->expat_capsule = _PyImport_GetModuleAttrString("pyexpat", "expat_CAPI");
if (st->expat_capsule == NULL) {
goto error;
}
st->expat_capi = PyCapsule_GetPointer(st->expat_capsule, PyExpat_CAPSULE_NAME);
if (st->expat_capi) {
/* check that it's usable */
if (strcmp(st->expat_capi->magic, PyExpat_CAPI_MAGIC) != 0 ||
Expand Down