From 08f7a230f74759cb8e723db898d1d05bb25a2943 Mon Sep 17 00:00:00 2001 From: Zackery Spytz Date: Tue, 26 May 2020 02:57:09 -0600 Subject: [PATCH] [3.8] bpo-35714: Reject null characters in struct format strings (GH-16928) (GH-20419) struct.error is now raised if there is a null character in a struct format string. (cherry picked from commit 3f59b55316f4c6ab451997902579aa69020b537c) (cherry picked from commit 5ff5edfef63b3dbc1abb004b3fa4b3db87e79ff9) Co-authored-by: Zackery Spytz --- Lib/test/test_struct.py | 7 +++++++ .../next/Library/2019-10-25-23-45-49.bpo-35714.fw3xb7.rst | 2 ++ Modules/_struct.c | 4 ++++ 3 files changed, 13 insertions(+) create mode 100644 Misc/NEWS.d/next/Library/2019-10-25-23-45-49.bpo-35714.fw3xb7.rst diff --git a/Lib/test/test_struct.py b/Lib/test/test_struct.py index 8fd56c91cb7a4d..104f4d30c9e1d7 100644 --- a/Lib/test/test_struct.py +++ b/Lib/test/test_struct.py @@ -626,6 +626,13 @@ def test_format_attr(self): s2 = struct.Struct(s.format.encode()) self.assertEqual(s2.format, s.format) + def test_issue35714(self): + # Embedded null characters should not be allowed in format strings. + for s in '\0', '2\0i', b'\0': + with self.assertRaisesRegex(struct.error, + 'embedded null character'): + struct.calcsize(s) + class UnpackIteratorTest(unittest.TestCase): """ diff --git a/Misc/NEWS.d/next/Library/2019-10-25-23-45-49.bpo-35714.fw3xb7.rst b/Misc/NEWS.d/next/Library/2019-10-25-23-45-49.bpo-35714.fw3xb7.rst new file mode 100644 index 00000000000000..39102065ca7b51 --- /dev/null +++ b/Misc/NEWS.d/next/Library/2019-10-25-23-45-49.bpo-35714.fw3xb7.rst @@ -0,0 +1,2 @@ +:exc:`struct.error` is now raised if there is a null character in a +:mod:`struct` format string. diff --git a/Modules/_struct.c b/Modules/_struct.c index c09951dcb79f31..4bde0ce9f06583 100644 --- a/Modules/_struct.c +++ b/Modules/_struct.c @@ -1285,6 +1285,10 @@ prepare_s(PyStructObject *self) size_t ncodes; fmt = PyBytes_AS_STRING(self->s_format); + if (strlen(fmt) != (size_t)PyBytes_GET_SIZE(self->s_format)) { + PyErr_SetString(StructError, "embedded null character"); + return -1; + } f = whichtable(&fmt);