del sqlite3.Connection.autocommit crashes

[serhiy-storchaka]

Crash report

import sqlite3
cx = sqlite3.connect(":memory:")
del cx.autocommit

set_autocommit() in Modules/_sqlite/connection.c passes the value to autocommit_converter(), which dereferences it in Py_IsTrue().
Deleting row_factory and text_factory of a connection is already rejected with an AttributeError (gh-149738); autocommit should be rejected too.

The same code is in 3.13, 3.14 and 3.15.

Linked PRs

• gh-156100: Fix crashes in the sqlite3 Connection.autocommit setter #156104

[serhiy-storchaka]

The same converter has a second bug: autocommit_converter() compares the result of PyLong_AsLong() with LEGACY_TRANSACTION_CONTROL, which is -1, the value returned on error.

cx.autocommit = 2**1000

is therefore accepted as LEGACY_TRANSACTION_CONTROL with OverflowError set, and the interpreter continues with a pending exception.
GH-156104 fixes both.