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bpo-44707: Fix an undefined behavior of the null pointer arithmetic (GH-27292) (GH-27443)

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(cherry picked from commit e5c8ddb171)

Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>
This commit is contained in:
Miss Islington (bot) 2021-07-29 05:05:43 -07:00 • committed by GitHub
parent 7922546859
commit 12fc0d28fc
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GPG key ID: 4AEE18F83AFDEB23
1 changed files with 9 additions and 2 deletions
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11
Objects/listobject.c
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@ -165,9 +165,10 @@ PyList_New(Py_ssize_t size)
static PyObject * static PyObject *
list_new_prealloc(Py_ssize_t size) list_new_prealloc(Py_ssize_t size)
{ {
assert(size > 0);
PyListObject *op = (PyListObject *) PyList_New(0); PyListObject *op = (PyListObject *) PyList_New(0);
if (size == 0 || op == NULL) { if (op == NULL) {
return (PyObject *) op; return NULL;
} }
assert(op->ob_item == NULL); assert(op->ob_item == NULL);
op->ob_item = PyMem_New(PyObject *, size); op->ob_item = PyMem_New(PyObject *, size);
@ -446,6 +447,9 @@ list_slice(PyListObject *a, Py_ssize_t ilow, Py_ssize_t ihigh)
PyObject **src, **dest; PyObject **src, **dest;
Py_ssize_t i, len; Py_ssize_t i, len;
len = ihigh - ilow; len = ihigh - ilow;
if (len <= 0) {
return PyList_New(0);
}
np = (PyListObject *) list_new_prealloc(len); np = (PyListObject *) list_new_prealloc(len);
if (np == NULL) if (np == NULL)
return NULL; return NULL;
@ -500,6 +504,9 @@ list_concat(PyListObject *a, PyObject *bb)
if (Py_SIZE(a) > PY_SSIZE_T_MAX - Py_SIZE(b)) if (Py_SIZE(a) > PY_SSIZE_T_MAX - Py_SIZE(b))
return PyErr_NoMemory(); return PyErr_NoMemory();
size = Py_SIZE(a) + Py_SIZE(b); size = Py_SIZE(a) + Py_SIZE(b);
if (size == 0) {
return PyList_New(0);
}
np = (PyListObject *) list_new_prealloc(size); np = (PyListObject *) list_new_prealloc(size);
if (np == NULL) { if (np == NULL) {
return NULL; return NULL;