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.
(cherry picked from commit 3f59b55316f4c6ab451997902579aa69020b537c)
Co-authored-by: Zackery Spytz <zspytz@gmail.com>
diff --git a/Lib/test/test_struct.py b/Lib/test/test_struct.py
index 4829fbe..b3f21ea 100644
--- a/Lib/test/test_struct.py
+++ b/Lib/test/test_struct.py
@@ -671,6 +671,14 @@
self.assertIn(b"Exception ignored in:", 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):
"""
Tests for iterative unpacking (struct.Struct.iter_unpack).
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 0000000..3910206
--- /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 13d8072..5984bb6 100644
--- a/Modules/_struct.c
+++ b/Modules/_struct.c
@@ -1296,6 +1296,11 @@
size_t ncodes;
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);