[3.12] gh-118314: Fix padding edge case in binascii.a2b_base64 strict mode (GH-118320) (GH-118691)

gh-118314: Fix padding edge case in binascii.a2b_base64 strict mode (GH-118320)

Fix an edge case in `binascii.a2b_base64` strict mode, where
excessive padding was not detected when no padding is necessary.

(cherry picked from commit fe47d9bee3)

Co-authored-by: Youfu Zhang <1315097+zhangyoufu@users.noreply.github.com>
Co-authored-by: Terry Jan Reedy <tjreedy@udel.edu>
Co-authored-by: Pieter Eendebak <pieter.eendebak@gmail.com>
This commit is contained in:
Miss Islington (bot) 2024-05-07 11:35:49 +02:00 committed by GitHub
parent 7b25d945e0
commit 56c61cc564
No known key found for this signature in database
GPG key ID: B5690EEEBB952194
3 changed files with 23 additions and 0 deletions

View file

@ -424,6 +424,13 @@ binascii_a2b_base64_impl(PyObject *module, Py_buffer *data, int strict_mode)
if (this_ch == BASE64_PAD) {
padding_started = 1;
if (strict_mode && quad_pos == 0) {
state = get_binascii_state(module);
if (state) {
PyErr_SetString(state->Error, "Excess padding not allowed");
}
goto error_end;
}
if (quad_pos >= 2 && quad_pos + ++pads >= 4) {
/* A pad sequence means we should not parse more input.
** We've already interpreted the data from the quad at this point.