Skip to content

bpo-31165: Detect mutated list in list_slice() #3911

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Closed
vstinner wants to merge 1 commit into from
Closed

bpo-31165: Detect mutated list in list_slice() #3911

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
2 changes: 2 additions & 0 deletions Misc/NEWS.d/next/Core and Builtins/2017-10-06-22-08-50.bpo-31165.rH1Z10.rst
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,2 @@
Detect mutated list in list_slice(): check if the list size changed
before/after allocating a new list object to prevent a crash.
16 changes: 11 additions & 5 deletions Objects/listobject.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -436,20 +436,26 @@ list_slice(PyListObject *a, Py_ssize_t ilow, Py_ssize_t ihigh)
{
PyListObject *np;
PyObject **src, **dest;
Py_ssize_t i, len;
Py_ssize_t alen, i, len;
alen = Py_SIZE(a);
if (ilow < 0)
ilow = 0;
else if (ilow > Py_SIZE(a))
ilow = Py_SIZE(a);
else if (ilow > alen)
ilow = alen;
if (ihigh < ilow)
ihigh = ilow;
else if (ihigh > Py_SIZE(a))
ihigh = Py_SIZE(a);
else if (ihigh > alen)
ihigh = alen;
len = ihigh - ilow;
np = (PyListObject *) PyList_New(len);
if (np == NULL)
return NULL;

if (Py_SIZE(a) != alen) {
PyErr_SetString(PyExc_RuntimeError, "list mutated during slicing");
return NULL;
}

src = a->ob_item + ilow;
dest = np->ob_item;
for (i = 0; i < len; i++) {
Expand Down