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bpo-35714: Reject null characters in struct format strings (GH-16928) 

struct.error is now raised if there is a null character in a struct
format string.
This commit is contained in:
Zackery Spytz 2020-05-25 01:55:09 -06:00 committed by GitHub
parent 372ee27d49
commit 3f59b55316
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GPG Key ID: 4AEE18F83AFDEB23
3 changed files with 15 additions and 0 deletions
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8
Lib/test/test_struct.py
View File

@ -671,6 +671,14 @@ class StructTest(unittest.TestCase):
self.assertIn(b"Exception ignored in:", stderr) self.assertIn(b"Exception ignored in:", stderr)
self.assertIn(b"C.__del__", stderr) self.assertIn(b"C.__del__", stderr)
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): class UnpackIteratorTest(unittest.TestCase):
""" """
Tests for iterative unpacking (struct.Struct.iter_unpack). Tests for iterative unpacking (struct.Struct.iter_unpack).

2
Misc/NEWS.d/next/Library/2019-10-25-23-45-49.bpo-35714.fw3xb7.rst Normal file
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@ -0,0 +1,2 @@
:exc:`struct.error` is now raised if there is a null character in a
:mod:`struct` format string.

5
Modules/_struct.c
View File

@ -1296,6 +1296,11 @@ prepare_s(PyStructObject *self)
size_t ncodes; size_t ncodes;
fmt = PyBytes_AS_STRING(self->s_format); fmt = PyBytes_AS_STRING(self->s_format);
if (strlen(fmt) != (size_t)PyBytes_GET_SIZE(self->s_format)) {
PyErr_SetString(_structmodulestate_global->StructError,
"embedded null character");
return -1;
}
f = whichtable(&fmt); f = whichtable(&fmt);