`sqlite3.Row()` crashes when given a `Cursor` whose `__init__` was not called

Crash report

What happened?

sqlite3.Row() reads cursor->description without checking that the cursor was initialized, so a NULL slot segfaults the interpreter:

❯ python3
Python 3.14.6 (main, Jun 10 2026, 18:54:31) [GCC 15.2.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import sqlite3
... sqlite3.Row(sqlite3.Cursor.__new__(sqlite3.Cursor), ())
...
Segmentation fault         (core dumped) python3

A PR is on the way.

CPython versions tested on:

3.14, CPython main branch

Operating systems tested on:

Linux

Output from running 'python -VV' on the command line:

No response

Linked PRs

• gh-156556

まず sqlite3.Row(sqlite3.Cursor.new(sqlite3.Cursor), ()) を使ってコマンドを再現し、次に初期化されていない Cursor に対する sqlite3.Row の処理を調べます。同じ入力でインタープリターが segfault しなくなり、回帰テストのカバレッジによって安全な動作が実証されれば完了です。