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[3.13] gh-128632: fix segfault on nested __classdict__ type param (GH-128744) (#132085)

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(cherry picked from commit 891c61c1fa)

Co-authored-by: Tomasz Pytel <tompytel@gmail.com>
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Tomasz Pytel 2025-04-04 11:23:40 -04:00 • committed by GitHub
parent d8986b7f5e
commit 900dc2b034
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4 changed files with 53 additions and 13 deletions
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19
Lib/test/test_syntax.py
View file

@ -2470,6 +2470,25 @@ if x:
self.assertRaises(IndentationError, exec, code)
@support.cpython_only
def test_disallowed_type_param_names(self):
# See gh-128632
self._check_error(f"class A[__classdict__]: pass",
f"reserved name '__classdict__' cannot be used for type parameter")
self._check_error(f"def f[__classdict__](): pass",
f"reserved name '__classdict__' cannot be used for type parameter")
self._check_error(f"type T[__classdict__] = tuple[__classdict__]",
f"reserved name '__classdict__' cannot be used for type parameter")
# These compilations are here to make sure __class__, __classcell__ and __classdictcell__
# don't break in the future like __classdict__ did in this case.
for name in ('__class__', '__classcell__', '__classdictcell__'):
compile(f"""
class A:
class B[{name}]: pass
""", "<testcase>", mode="exec")
@support.cpython_only
def test_nested_named_except_blocks(self):
code = ""

2
Misc/NEWS.d/next/Core_and_Builtins/2025-01-11-20-11-28.gh-issue-128632.ryhnKs.rst Normal file
View file

@ -0,0 +1,2 @@
Disallow ``__classdict__`` as the name of a type parameter. Using this
name would previously crash the interpreter in some circumstances.

18
Python/assemble.c
View file

@ -503,7 +503,7 @@ compute_localsplus_info(_PyCompile_CodeUnitMetadata *umd, int nlocalsplus,
int nlocals = (int)PyDict_GET_SIZE(umd->u_varnames);
// This counter mirrors the fix done in fix_cell_offsets().
int numdropped = 0;
int numdropped = 0, cellvar_offset = -1;
pos = 0;
while (PyDict_Next(umd->u_cellvars, &pos, &k, &v)) {
int has_name = PyDict_Contains(umd->u_varnames, k);
@ -514,14 +514,14 @@ compute_localsplus_info(_PyCompile_CodeUnitMetadata *umd, int nlocalsplus,
continue;
}
int offset = PyLong_AsInt(v);
if (offset == -1 && PyErr_Occurred()) {
cellvar_offset = PyLong_AsInt(v);
if (cellvar_offset == -1 && PyErr_Occurred()) {
return ERROR;
}
assert(offset >= 0);
offset += nlocals - numdropped;
assert(offset < nlocalsplus);
_Py_set_localsplus_info(offset, k, CO_FAST_CELL, names, kinds);
assert(cellvar_offset >= 0);
cellvar_offset += nlocals - numdropped;
assert(cellvar_offset < nlocalsplus);
_Py_set_localsplus_info(cellvar_offset, k, CO_FAST_CELL, names, kinds);
}
pos = 0;
@ -533,6 +533,10 @@ compute_localsplus_info(_PyCompile_CodeUnitMetadata *umd, int nlocalsplus,
assert(offset >= 0);
offset += nlocals - numdropped;
assert(offset < nlocalsplus);
/* XXX If the assertion below fails it is most likely because a freevar
was added to u_freevars with the wrong index due to not taking into
account cellvars already present, see gh-128632. */
assert(offset > cellvar_offset);
_Py_set_localsplus_info(offset, k, CO_FAST_FREE, names, kinds);
}
return SUCCESS;

27
Python/symtable.c
View file

@ -2292,12 +2292,27 @@ symtable_visit_expr(struct symtable *st, expr_ty e)
static int
symtable_visit_type_param_bound_or_default(
struct symtable *st, expr_ty e, identifier name,
void *key, const char *ste_scope_info)
type_param_ty tp, const char *ste_scope_info)
{
if (_PyUnicode_Equal(name, &_Py_ID(__classdict__))) {
PyObject *error_msg = PyUnicode_FromFormat("reserved name '%U' cannot be "
"used for type parameter", name);
PyErr_SetObject(PyExc_SyntaxError, error_msg);
Py_DECREF(error_msg);
PyErr_RangedSyntaxLocationObject(st->st_filename,
tp->lineno,
tp->col_offset + 1,
tp->end_lineno,
tp->end_col_offset + 1);
return 0;
}
if (e) {
int is_in_class = st->st_cur->ste_can_see_class_scope;
if (!symtable_enter_block(st, name, TypeVariableBlock, key, LOCATION(e)))
if (!symtable_enter_block(st, name, TypeVariableBlock, (void *)tp, LOCATION(e))) {
return 0;
}
st->st_cur->ste_can_see_class_scope = is_in_class;
if (is_in_class && !symtable_add_def(st, &_Py_ID(__classdict__), USE, LOCATION(e))) {
@ -2341,12 +2356,12 @@ symtable_visit_type_param(struct symtable *st, type_param_ty tp)
// The only requirement for the key is that it is unique and it matches the logic in
// compile.c where the scope is retrieved.
if (!symtable_visit_type_param_bound_or_default(st, tp->v.TypeVar.bound, tp->v.TypeVar.name,
(void *)tp, ste_scope_info)) {
tp, ste_scope_info)) {
VISIT_QUIT(st, 0);
}
if (!symtable_visit_type_param_bound_or_default(st, tp->v.TypeVar.default_value, tp->v.TypeVar.name,
(void *)((uintptr_t)tp + 1), "a TypeVar default")) {
(type_param_ty)((uintptr_t)tp + 1), "a TypeVar default")) {
VISIT_QUIT(st, 0);
}
break;
@ -2356,7 +2371,7 @@ symtable_visit_type_param(struct symtable *st, type_param_ty tp)
}
if (!symtable_visit_type_param_bound_or_default(st, tp->v.TypeVarTuple.default_value, tp->v.TypeVarTuple.name,
(void *)tp, "a TypeVarTuple default")) {
tp, "a TypeVarTuple default")) {
VISIT_QUIT(st, 0);
}
break;
@ -2366,7 +2381,7 @@ symtable_visit_type_param(struct symtable *st, type_param_ty tp)
}
if (!symtable_visit_type_param_bound_or_default(st, tp->v.ParamSpec.default_value, tp->v.ParamSpec.name,
(void *)tp, "a ParamSpec default")) {
tp, "a ParamSpec default")) {
VISIT_QUIT(st, 0);
}
break;