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gh-99537: Use Py_SETREF() function in C code (#99657) 

Fix potential race condition in code patterns:

* Replace "Py_DECREF(var); var = new;" with "Py_SETREF(var, new);"
* Replace "Py_XDECREF(var); var = new;" with "Py_XSETREF(var, new);"
* Replace "Py_CLEAR(var); var = new;" with "Py_XSETREF(var, new);"

Other changes:

* Replace "old = var; var = new; Py_DECREF(var)"
  with "Py_SETREF(var, new);"
* Replace "old = var; var = new; Py_XDECREF(var)"
  with "Py_XSETREF(var, new);"
* And remove the "old" variable.
This commit is contained in:
Victor Stinner 2022-11-22 13:39:11 +01:00 committed by GitHub
parent 3db0a21f73
commit 135ec7cefb
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
19 changed files with 34 additions and 76 deletions
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4
Objects/bytesobject.c
View File

@ -2109,9 +2109,7 @@ bytes_translate_impl(PyBytesObject *self, PyObject *table,
changed = 1;
}
if (!changed && PyBytes_CheckExact(input_obj)) {
Py_INCREF(input_obj);
Py_DECREF(result);
result = input_obj;
Py_SETREF(result, Py_NewRef(input_obj));
}
PyBuffer_Release(&del_table_view);
PyBuffer_Release(&table_view);

3
Objects/capsule.c
View File

@ -220,8 +220,7 @@ PyCapsule_Import(const char *name, int no_block)
}
} else {
PyObject *object2 = PyObject_GetAttrString(object, trace);
Py_DECREF(object);
object = object2;
Py_SETREF(object, object2);
}
if (!object) {
goto EXIT;

6
Objects/fileobject.c
View File

@ -88,8 +88,7 @@ PyFile_GetLine(PyObject *f, int n)
else {
PyObject *v;
v = PyBytes_FromStringAndSize(s, len-1);
Py_DECREF(result);
result = v;
Py_SETREF(result, v);
}
}
}
@ -104,8 +103,7 @@ PyFile_GetLine(PyObject *f, int n)
else if (PyUnicode_READ_CHAR(result, len-1) == '\n') {
PyObject *v;
v = PyUnicode_Substring(result, 0, len-1);
Py_DECREF(result);
result = v;
Py_SETREF(result, v);
}
}
return result;

9
Objects/floatobject.c
View File

@ -531,20 +531,17 @@ float_richcompare(PyObject *v, PyObject *w, int op)
temp = _PyLong_Lshift(ww, 1);
if (temp == NULL)
goto Error;
Py_DECREF(ww);
ww = temp;
Py_SETREF(ww, temp);
temp = _PyLong_Lshift(vv, 1);
if (temp == NULL)
goto Error;
Py_DECREF(vv);
vv = temp;
Py_SETREF(vv, temp);
temp = PyNumber_Or(vv, _PyLong_GetOne());
if (temp == NULL)
goto Error;
Py_DECREF(vv);
vv = temp;
Py_SETREF(vv, temp);
}
r = PyObject_RichCompareBool(vv, ww, op);

3
Objects/genobject.c
View File

@ -491,8 +491,7 @@ throw_here:
}
else {
/* Normalize to raise <class>, <instance> */
Py_XDECREF(val);
val = typ;
Py_XSETREF(val, typ);
typ = Py_NewRef(PyExceptionInstance_Class(typ));
if (tb == NULL)

3
Objects/setobject.c
View File

@ -1270,8 +1270,7 @@ set_intersection_multi(PySetObject *so, PyObject *args)
Py_DECREF(result);
return NULL;
}
Py_DECREF(result);
result = newresult;
Py_SETREF(result, newresult);
}
return result;
}

22
Objects/sliceobject.c
View File

@ -448,8 +448,7 @@ _PySlice_GetLongIndices(PySliceObject *self, PyObject *length,
if (_PyLong_Sign(start) < 0) {
/* start += length */
PyObject *tmp = PyNumber_Add(start, length);
Py_DECREF(start);
start = tmp;
Py_SETREF(start, tmp);
if (start == NULL)
goto error;
@ -457,9 +456,7 @@ _PySlice_GetLongIndices(PySliceObject *self, PyObject *length,
if (cmp_result < 0)
goto error;
if (cmp_result) {
Py_INCREF(lower);
Py_DECREF(start);
start = lower;
Py_SETREF(start, Py_NewRef(lower));
}
}
else {
@ -467,9 +464,7 @@ _PySlice_GetLongIndices(PySliceObject *self, PyObject *length,
if (cmp_result < 0)
goto error;
if (cmp_result) {
Py_INCREF(upper);
Py_DECREF(start);
start = upper;
Py_SETREF(start, Py_NewRef(upper));
}
}
}
@ -486,8 +481,7 @@ _PySlice_GetLongIndices(PySliceObject *self, PyObject *length,
if (_PyLong_Sign(stop) < 0) {
/* stop += length */
PyObject *tmp = PyNumber_Add(stop, length);
Py_DECREF(stop);
stop = tmp;
Py_SETREF(stop, tmp);
if (stop == NULL)
goto error;
@ -495,9 +489,7 @@ _PySlice_GetLongIndices(PySliceObject *self, PyObject *length,
if (cmp_result < 0)
goto error;
if (cmp_result) {
Py_INCREF(lower);
Py_DECREF(stop);
stop = lower;
Py_SETREF(stop, Py_NewRef(lower));
}
}
else {
@ -505,9 +497,7 @@ _PySlice_GetLongIndices(PySliceObject *self, PyObject *length,
if (cmp_result < 0)
goto error;
if (cmp_result) {
Py_INCREF(upper);
Py_DECREF(stop);
stop = upper;
Py_SETREF(stop, Py_NewRef(upper));
}
}
}

6
Objects/stringlib/unicode_format.h
View File

@ -473,8 +473,7 @@ get_field_object(SubString *input, PyObject *args, PyObject *kwargs,
goto error;
/* assign to obj */
Py_DECREF(obj);
obj = tmp;
Py_SETREF(obj, tmp);
}
/* end of iterator, this is the non-error case */
if (ok == 1)
@ -825,8 +824,7 @@ output_markup(SubString *field_name, SubString *format_spec,
goto done;
/* do the assignment, transferring ownership: fieldobj = tmp */
Py_DECREF(fieldobj);
fieldobj = tmp;
Py_SETREF(fieldobj, tmp);
tmp = NULL;
}

6
Objects/typeobject.c
View File

@ -5968,8 +5968,7 @@ object___dir___impl(PyObject *self)
else {
/* Copy __dict__ to avoid mutating it. */
PyObject *temp = PyDict_Copy(dict);
Py_DECREF(dict);
dict = temp;
Py_SETREF(dict, temp);
}
if (dict == NULL)
@ -9377,8 +9376,7 @@ super_getattro(PyObject *self, PyObject *name)
(See SF ID #743627) */
(su->obj == (PyObject *)starttype) ? NULL : su->obj,
(PyObject *)starttype);
Py_DECREF(res);
res = res2;
Py_SETREF(res, res2);
}
Py_DECREF(mro);

6
Objects/unicodeobject.c
View File

@ -13572,8 +13572,7 @@ _PyUnicode_FormatLong(PyObject *val, int alt, int prec, int type)
for (i = 0; i < numdigits; i++)
*b1++ = *buf++;
*b1 = '\0';
Py_DECREF(result);
result = r1;
Py_SETREF(result, r1);
buf = PyBytes_AS_STRING(result);
len = numnondigits + prec;
}
@ -13590,8 +13589,7 @@ _PyUnicode_FormatLong(PyObject *val, int alt, int prec, int type)
|| buf != PyUnicode_DATA(result)) {
PyObject *unicode;
unicode = _PyUnicode_FromASCII(buf, len);
Py_DECREF(result);
result = unicode;
Py_SETREF(result, unicode);
}
else if (len != PyUnicode_GET_LENGTH(result)) {
if (PyUnicode_Resize(&result, len) < 0)

6
Objects/weakrefobject.c
View File

@ -824,8 +824,7 @@ PyWeakref_NewRef(PyObject *ob, PyObject *callback)
during GC. Return that one instead of this one
to avoid violating the invariants of the list
of weakrefs for ob. */
Py_DECREF(result);
result = (PyWeakReference*)Py_NewRef(ref);
Py_SETREF(result, (PyWeakReference*)Py_NewRef(ref));
}
}
else {
@ -888,8 +887,7 @@ PyWeakref_NewProxy(PyObject *ob, PyObject *callback)
during GC. Return that one instead of this one
to avoid violating the invariants of the list
of weakrefs for ob. */
Py_DECREF(result);
result = (PyWeakReference*)Py_NewRef(proxy);
Py_SETREF(result, (PyWeakReference*)Py_NewRef(proxy));
goto skip_insert;
}
prev = ref;

6
Python/_warnings.c
View File

@ -801,8 +801,7 @@ next_external_frame(PyFrameObject *frame)
{
do {
PyFrameObject *back = PyFrame_GetBack(frame);
Py_DECREF(frame);
frame = back;
Py_SETREF(frame, back);
} while (frame != NULL && is_internal_frame(frame));
return frame;
@ -828,8 +827,7 @@ setup_context(Py_ssize_t stack_level, PyObject **filename, int *lineno,
if (stack_level <= 0 || is_internal_frame(f)) {
while (--stack_level > 0 && f != NULL) {
PyFrameObject *back = PyFrame_GetBack(f);
Py_DECREF(f);
f = back;
Py_SETREF(f, back);
}
}
else {

3
Python/bltinmodule.c
View File

@ -168,8 +168,7 @@ builtin___build_class__(PyObject *self, PyObject *const *args, Py_ssize_t nargs,
goto error;
}
if (winner != meta) {
Py_DECREF(meta);
meta = Py_NewRef(winner);
Py_SETREF(meta, Py_NewRef(winner));
}
}
/* else: meta is not a class, so we cannot do the metaclass

4
Python/compile.c
View File

@ -8280,9 +8280,7 @@ merge_const_one(PyObject *const_cache, PyObject **obj)
t = PyTuple_GET_ITEM(t, 1);
}
Py_INCREF(t);
Py_DECREF(*obj);
*obj = t;
Py_SETREF(*obj, Py_NewRef(t));
return 1;
}

7
Python/errors.c
View File

@ -353,16 +353,13 @@ _PyErr_NormalizeException(PyThreadState *tstate, PyObject **exc,
if (fixed_value == NULL) {
goto error;
}
Py_DECREF(value);
value = fixed_value;
Py_SETREF(value, fixed_value);
}
/* If the class of the instance doesn't exactly match the
class of the type, believe the instance.
*/
else if (inclass != type) {
Py_INCREF(inclass);
Py_DECREF(type);
type = inclass;
Py_SETREF(type, Py_NewRef(inclass));
}
}
*exc = type;

3
Python/hamt.c
View File

@ -1354,8 +1354,7 @@ hamt_node_collision_assoc(PyHamtNode_Collision *self,
}
/* Replace the old value with the new value for the our key. */
Py_DECREF(new_node->c_array[val_idx]);
new_node->c_array[val_idx] = Py_NewRef(val);
Py_SETREF(new_node->c_array[val_idx], Py_NewRef(val));
return (PyHamtNode *)new_node;

3
Python/pythonrun.c
View File

@ -718,8 +718,7 @@ _Py_HandleSystemExit(int *exitcode_p)
/* The error code should be in the `code' attribute. */
PyObject *code = PyObject_GetAttr(value, &_Py_ID(code));
if (code) {
Py_DECREF(value);
value = code;
Py_SETREF(value, code);
if (value == Py_None)
goto done;
}

3
Python/sysmodule.c
View File

@ -198,8 +198,7 @@ sys_audit_tstate(PyThreadState *ts, const char *event,
eventArgs = _Py_VaBuildValue_SizeT(argFormat, vargs);
if (eventArgs && !PyTuple_Check(eventArgs)) {
PyObject *argTuple = PyTuple_Pack(1, eventArgs);
Py_DECREF(eventArgs);
eventArgs = argTuple;
Py_SETREF(eventArgs, argTuple);
}
}
else {

7
Python/traceback.c
View File

@ -136,9 +136,7 @@ tb_next_set(PyTracebackObject *self, PyObject *new_next, void *Py_UNUSED(_))
cursor = cursor->tb_next;
}
PyObject *old_next = (PyObject*)self->tb_next;
self->tb_next = (PyTracebackObject *)Py_XNewRef(new_next);
Py_XDECREF(old_next);
Py_XSETREF(self->tb_next, (PyTracebackObject *)Py_XNewRef(new_next));
return 0;
}
@ -533,8 +531,7 @@ display_source_line_with_margin(PyObject *f, PyObject *filename, int lineno, int
PyObject *truncated;
truncated = PyUnicode_Substring(lineobj, i, PyUnicode_GET_LENGTH(lineobj));
if (truncated) {
Py_DECREF(lineobj);
lineobj = truncated;
Py_SETREF(lineobj, truncated);
} else {
PyErr_Clear();
}