[3.11] gh-99886: Fix crash when freeing objects with managed dictionaries

[Fidget-Spinner]

• Issue: Segmentation fault when using a subclassed sqlite3.Cursor on 3.11.x #99886

[markshannon]

We should probably remove the reference to the values array, before we clear it.

[erlend-aasland]

I don't know the internal parts good enough to comment on them; I trust you here :) The test looks ok, but perhaps we should add a more general test case; buildbots without SQLite installed won't have the sqlite3 module, so this test won't run.

[Fidget-Spinner]

... perhaps we should add a more general test case; buildbots without SQLite installed won't have the sqlite3 module, so this test won't run.

I agree. However I'm not sure what exactly is causing this. My general idea is that something is causing the tp_traverse function to be called multiple times on the same instance, but I don't know why inheriting from sqlite.Cursor causes this. I will try to create a test case without sqlite but it's possible that I won't be able to find it before the next 3.11 release :(. Sorry.

[erlend-aasland]

I agree. However I'm not sure what exactly is causing this. My general idea is that something is causing the tp_traverse function to be called multiple times on the same instance, but I don't know why inheriting from sqlite.Cursor causes this. I will try to create a test case without sqlite but it's possible that I won't be able to find it before the next 3.11 release :(. Sorry.

No sweat! Thanks so much for the quick fix!

[kumaraditya303]

LGTM

[Fidget-Spinner]

Thanks for the reviews, Erlend and Kumar!