Skip to content

[3.14] gh-159739: Reject the minimum dynamic formatting width (GH-159780) #159931

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

Merged
JelleZijlstra merged 1 commit into from
Oct 20, 2026
Merged

[3.14] gh-159739: Reject the minimum dynamic formatting width (GH-159780) #159931

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 Lib/test/test_format.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -287,6 +287,8 @@ def test_common_format(self):
"%i format: a real number is required, not str")
test_exc_common('%i', b'1', TypeError,
"%i format: a real number is required, not bytes")
test_exc_common('%*r', (-maxsize - 1, 1), OverflowError,
"width too big")

def test_str_format(self):
testformat("%r", "\u0378", "'\\u0378'") # non printable
Expand Down
2 changes: 2 additions & 0 deletions Misc/NEWS.d/next/Core_and_Builtins/2026-10-19-20-38-17.gh-issue-159739.78e530.rst
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,2 @@
Raise :exc:`OverflowError` when the absolute value of a dynamic printf-style
formatting width is too large.
4 changes: 4 additions & 0 deletions Objects/bytesobject.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -752,6 +752,10 @@ _PyBytes_FormatEx(const char *format, Py_ssize_t format_len,
if (width == -1 && PyErr_Occurred())
goto error;
if (width < 0) {
if (width == PY_SSIZE_T_MIN) {
PyErr_SetString(PyExc_OverflowError, "width too big");
goto error;
}
flags |= F_LJUST;
width = -width;
}
Expand Down
4 changes: 4 additions & 0 deletions Objects/unicodeobject.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -15150,6 +15150,10 @@ unicode_format_arg_parse(struct unicode_formatter_t *ctx,
if (arg->width == -1 && PyErr_Occurred())
return -1;
if (arg->width < 0) {
if (arg->width == PY_SSIZE_T_MIN) {
PyErr_SetString(PyExc_OverflowError, "width too big");
return -1;
}
arg->flags |= F_LJUST;
arg->width = -arg->width;
}
Expand Down
Loading