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gh-161388: [tkinter] Fix crash on raising __str__ method passed to setvar #161397

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gh-161388: [tkinter] Fix crash on raising __str__ method passed to setvar #161397

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gh-161388: [tkinter] Fix crash on raising `__str__` method passed to …
sobolevn Nov 5, 2026
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sobolevn Nov 5, 2026
90eb612
Update Modules/_tkinter.c
sobolevn Nov 5, 2026
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sobolevn Nov 5, 2026
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29 changes: 29 additions & 0 deletions Lib/test/test_tcl.py
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Original file line number Diff line number Diff line change
Expand Up @@ -596,6 +596,35 @@ def test_returning_deeply_nested(self):
% support.exceeds_recursion_limit())
self.assertRaises(RecursionError, interp.getvar, 'x')

def test_setvar_evil(self):
# gh-161388
class StrRaises:
def __str__(self):
raise RuntimeError("setvar evil")

default = StrRaises()

for getvar, setvar, unsetvar in [

@serhiy-storchaka serhiy-storchaka Nov 6, 2026

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Would not the following be easier to read?

for prefix in '', 'global':
    with self.subTest(...):
        getvar = getattr(self.interp.tk.getvar, prefix + 'getvar')
        ...

Or simply repeat these few lines like in other tests (with shortcut tk = self.interp.tk).

(
self.interp.tk.getvar,
self.interp.tk.setvar,
self.interp.tk.unsetvar,
),
(
self.interp.tk.globalgetvar,
self.interp.tk.globalsetvar,
self.interp.tk.globalunsetvar,
)
]:
with self.subTest(getvar=getvar, setvar=setvar, unsetvar=unsetvar):
with self.assertRaisesRegex(RuntimeError, "setvar evil"):
setvar("name1", "name2", default)

self.assertRaises(TclError, getvar, "name1")

@serhiy-storchaka serhiy-storchaka Nov 6, 2026

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It should pass "name1", "name2" if you want to check the value of $name1(name2).

self.assertIsNone(setvar("name1", "name2"))

@serhiy-storchaka serhiy-storchaka Nov 6, 2026

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I meant setvar("name1", default).

BTW, I would rename default to value.

self.assertEqual(getvar("name1"), "name2")
self.assertIsNone(unsetvar("name1"))

def test_user_command(self):
result = None
def testfunc(arg):
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8 changes: 6 additions & 2 deletions Modules/_tkinter.c
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Expand Up @@ -1234,8 +1234,9 @@ AsObjNested(PyObject *value, int depth)

{
PyObject *v = PyObject_Str(value);
if (!v)
return 0;
if (!v) {
return NULL;
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}
result = AsObjNested(v, depth);
Py_DECREF(v);
return result;
Expand Down Expand Up @@ -2101,6 +2102,9 @@ SetVar(TkappObject *self, PyObject *args, int flags)

/* XXX must hold tcl lock already??? */
newval = AsObj(newValue);
if (newval == NULL) {
return NULL;
}
if (self->trace) {
if (flags & TCL_GLOBAL_ONLY) {
TRACE(self, ("((sssNO))", "uplevel", "#0", "set",
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