Remove test_max_str_len

hexagonrecursion · hexagonrecursion · commit 8feb8dc63e05 · 2021-02-26T16:06:27.000+03:00
It appears this test was verifying a quirk of the DoS protection.
When the input is supplied via feed() BufferFull is raised to prevent
excessive memory allocation. When the input is supplied via a file
ValueError is raised when the length of the bin, str or ext is too big.

The fallback implementation had a quirk: it would raise ValueError when
the length of the is too big even when the input is supplied via feed().
As far as I can tell removing this quirk does not introduce a
vulnerability. I have fixed the quirk making this test obsolete.
This also allowed me to remove the code from the extension the appears
to serve only one purpose: make this test pass.
diff --git a/msgpack/unpack.h b/msgpack/unpack.h
@@ -231,11 +231,6 @@ static inline int unpack_callback_map_end(unpack_user* u, msgpack_unpack_object*
 
 static inline int unpack_callback_raw(unpack_user* u, const char* b, const char* p, unsigned int l, msgpack_unpack_object* o)
 {
-    if (l > u->max_str_len) {
-        PyErr_Format(PyExc_ValueError, "%u exceeds max_str_len(%zd)", l, u->max_str_len);
-        return -1;
-    }
-
     PyObject *py;
 
     if (u->raw) {
diff --git a/test/test_limits.py b/test/test_limits.py
@@ -41,20 +41,6 @@ def test_map_header():
         packer.pack_array_header(2 ** 32)
 
 
-def test_max_str_len():
-    d = "x" * 3
-    packed = packb(d)
-
-    unpacker = Unpacker(max_str_len=3, raw=False)
-    unpacker.feed(packed)
-    assert unpacker.unpack() == d
-
-    unpacker = Unpacker(max_str_len=2, raw=False)
-    with pytest.raises(UnpackValueError):
-        unpacker.feed(packed)
-        unpacker.unpack()
-
-
 def test_max_array_len():
     d = [1, 2, 3]
     packed = packb(d)
