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gh-127945: fix thread safety and add lock held assertions to paramfunc in ctypes (#132473)

This commit is contained in:
Kumar Aditya 2025-04-14 14:05:06 +05:30 committed by GitHub
parent 522766aa23
commit be763e550e
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GPG Key ID: B5690EEEBB952194
3 changed files with 23 additions and 40 deletions
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50
Modules/_ctypes/_ctypes.c
View File

@ -595,8 +595,14 @@ PyType_Spec pyctype_type_spec = {
.slots = ctype_type_slots,
};
/*
PyCStructType_Type - a meta type/class. Creating a new class using this one as
__metaclass__ will call the constructor StructUnionType_new.
It initializes the C accessible fields somehow.
*/
static PyCArgObject *
StructUnionType_paramfunc_lock_held(ctypes_state *st, CDataObject *self)
StructUnionType_paramfunc(ctypes_state *st, CDataObject *self)
{
_Py_CRITICAL_SECTION_ASSERT_OBJECT_LOCKED(self);
PyCArgObject *parg;
@ -649,20 +655,6 @@ StructUnionType_paramfunc_lock_held(ctypes_state *st, CDataObject *self)
return parg;
}
/*
PyCStructType_Type - a meta type/class. Creating a new class using this one as
__metaclass__ will call the constructor StructUnionType_new.
It initializes the C accessible fields somehow.
*/
static PyCArgObject *
StructUnionType_paramfunc(ctypes_state *st, CDataObject *self)
{
PyCArgObject *res;
Py_BEGIN_CRITICAL_SECTION(self);
res = StructUnionType_paramfunc_lock_held(st, self);
Py_END_CRITICAL_SECTION();
return res;
}
static int
StructUnionType_init(PyObject *self, PyObject *args, PyObject *kwds, int isStruct)
@ -1213,6 +1205,7 @@ PyCPointerType_SetProto(ctypes_state *st, StgInfo *stginfo, PyObject *proto)
static PyCArgObject *
PyCPointerType_paramfunc(ctypes_state *st, CDataObject *self)
{
_Py_CRITICAL_SECTION_ASSERT_OBJECT_LOCKED(self);
PyCArgObject *parg;
parg = PyCArgObject_new(st);
@ -1222,7 +1215,7 @@ PyCPointerType_paramfunc(ctypes_state *st, CDataObject *self)
parg->tag = 'P';
parg->pffi_type = &ffi_type_pointer;
parg->obj = Py_NewRef(self);
parg->value.p = locked_deref(self);
parg->value.p = *(void **)self->b_ptr;
return parg;
}
@ -1665,6 +1658,7 @@ add_getset(PyTypeObject *type, PyGetSetDef *gsp)
static PyCArgObject *
PyCArrayType_paramfunc(ctypes_state *st, CDataObject *self)
{
_Py_CRITICAL_SECTION_ASSERT_OBJECT_LOCKED(self);
PyCArgObject *p = PyCArgObject_new(st);
if (p == NULL)
return NULL;
@ -2159,7 +2153,9 @@ c_void_p_from_param_impl(PyObject *type, PyTypeObject *cls, PyObject *value)
parg->tag = 'Z';
parg->obj = Py_NewRef(value);
/* Remember: b_ptr points to where the pointer is stored! */
parg->value.p = locked_deref((CDataObject *)value);
Py_BEGIN_CRITICAL_SECTION(value);
parg->value.p = *(void **)_CDataObject_CAST(value)->b_ptr;
Py_END_CRITICAL_SECTION();
return (PyObject *)parg;
}
}
@ -2241,7 +2237,7 @@ static PyObject *CreateSwappedType(ctypes_state *st, PyTypeObject *type,
}
static PyCArgObject *
PyCSimpleType_paramfunc_lock_held(ctypes_state *st, CDataObject *self)
PyCSimpleType_paramfunc(ctypes_state *st, CDataObject *self)
{
_Py_CRITICAL_SECTION_ASSERT_OBJECT_LOCKED(self);
const char *fmt;
@ -2270,15 +2266,6 @@ PyCSimpleType_paramfunc_lock_held(ctypes_state *st, CDataObject *self)
return parg;
}
static PyCArgObject *
PyCSimpleType_paramfunc(ctypes_state *st, CDataObject *self)
{
PyCArgObject *res;
Py_BEGIN_CRITICAL_SECTION(self);
res = PyCSimpleType_paramfunc_lock_held(st, self);
Py_END_CRITICAL_SECTION();
return res;
}
static int
PyCSimpleType_init(PyObject *self, PyObject *args, PyObject *kwds)
@ -2766,6 +2753,7 @@ make_funcptrtype_dict(ctypes_state *st, PyObject *attrdict, StgInfo *stginfo)
static PyCArgObject *
PyCFuncPtrType_paramfunc(ctypes_state *st, CDataObject *self)
{
_Py_CRITICAL_SECTION_ASSERT_OBJECT_LOCKED(self);
PyCArgObject *parg;
parg = PyCArgObject_new(st);
@ -2775,7 +2763,7 @@ PyCFuncPtrType_paramfunc(ctypes_state *st, CDataObject *self)
parg->tag = 'P';
parg->pffi_type = &ffi_type_pointer;
parg->obj = Py_NewRef(self);
parg->value.p = locked_deref(self);
parg->value.p = *(void **)self->b_ptr;
return parg;
}
@ -5827,7 +5815,11 @@ Pointer_subscript(PyObject *myself, PyObject *item)
static int
Pointer_bool(PyObject *self)
{
return locked_deref(_CDataObject_CAST(self)) != NULL;
int res;
Py_BEGIN_CRITICAL_SECTION(self);
res = *(void **)_CDataObject_CAST(self)->b_ptr != NULL;
Py_END_CRITICAL_SECTION();
return res;
}
static PyType_Slot pycpointer_slots[] = {

2
Modules/_ctypes/callproc.c
View File

@ -683,7 +683,9 @@ static int ConvParam(ctypes_state *st,
PyCArgObject *carg;
assert(info->paramfunc);
/* If it has an stginfo, it is a CDataObject */
Py_BEGIN_CRITICAL_SECTION(obj);
carg = info->paramfunc(st, (CDataObject *)obj);
Py_END_CRITICAL_SECTION();
if (carg == NULL)
return -1;
pa->ffi_type = carg->pffi_type;

11
Modules/_ctypes/ctypes.h
View File

@ -643,14 +643,3 @@ PyStgInfo_Init(ctypes_state *state, PyTypeObject *type)
info->initialized = 1;
return info;
}
/* Equivalent to *self->b_ptr with a lock. */
static inline void *
locked_deref(CDataObject *self)
{
void *ptr;
Py_BEGIN_CRITICAL_SECTION(self);
ptr = *(void **)self->b_ptr;
Py_END_CRITICAL_SECTION();
return ptr;
}