https://github.com/python/cpython/commit/20c33c1a6603594c296b82379d7296fc1e2697e4
commit: 20c33c1a6603594c296b82379d7296fc1e2697e4
branch: 3.14
author: Jelle Zijlstra <[email protected]>
committer: JelleZijlstra <[email protected]>
date: 2026-10-20T19:28:30Z
summary:
[3.14] gh-159739: Reject the minimum dynamic formatting width (GH-159780)
(#159931)
Adapt the str formatting fix to Objects/unicodeobject.c and use the error
wording already present in the 3.14 formatters.
(cherry picked from commit 95f94d04d8772f926b6a9bc1e38b67218a1dba7a)
files:
A
Misc/NEWS.d/next/Core_and_Builtins/2026-10-19-20-38-17.gh-issue-159739.78e530.rst
M Lib/test/test_format.py
M Objects/bytesobject.c
M Objects/unicodeobject.c
diff --git a/Lib/test/test_format.py b/Lib/test/test_format.py
index 120c719b5eb79e..bc6eac99310a9c 100644
--- a/Lib/test/test_format.py
+++ b/Lib/test/test_format.py
@@ -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
diff --git
a/Misc/NEWS.d/next/Core_and_Builtins/2026-10-19-20-38-17.gh-issue-159739.78e530.rst
b/Misc/NEWS.d/next/Core_and_Builtins/2026-10-19-20-38-17.gh-issue-159739.78e530.rst
new file mode 100644
index 00000000000000..999efdac87f974
--- /dev/null
+++
b/Misc/NEWS.d/next/Core_and_Builtins/2026-10-19-20-38-17.gh-issue-159739.78e530.rst
@@ -0,0 +1,2 @@
+Raise :exc:`OverflowError` when the absolute value of a dynamic printf-style
+formatting width is too large.
diff --git a/Objects/bytesobject.c b/Objects/bytesobject.c
index 63730630e68497..307a015a119b9f 100644
--- a/Objects/bytesobject.c
+++ b/Objects/bytesobject.c
@@ -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;
}
diff --git a/Objects/unicodeobject.c b/Objects/unicodeobject.c
index 8023bed17d3ea9..d62ea36ed70d68 100644
--- a/Objects/unicodeobject.c
+++ b/Objects/unicodeobject.c
@@ -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;
}
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