deleting sqlite3 row_factory causes segfault

[lunixbochs]

Crash report

What happened?

import sqlite3
db = sqlite3.connect(":memory:")
del db.row_factory
db.execute("test")

-> zsh: segmentation fault python3

In connection.c, the row_factory is compared against Py_None and incref'd, but deleting it sets it to null, resulting in Py_INCREF(NULL)

CPython versions tested on:

3.14

Operating systems tested on:

macOS

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

No response

Linked PRs

• gh-149738: Fix segmentation fault bug in sqllite3 #149754
• [3.15] gh-149738: Fix segmentation fault bug in sqllite3 (GH-149754) #150768
• [3.14] gh-149738: Fix segmentation fault bug in sqllite3 (GH-149754) #150769
• [3.13] gh-149738: Fix segmentation fault bug in sqllite3 (#149754) #150770

[sepehr-rs]

Hi @lunixbochs, thanks for the clear report!
I can work on a fix for this if nobody is already doing so.
It may also make sense to add the topic-sqlite3 and stdlib labels.

[sharktide]

Hi @lunixbochs, thanks for the clear report!
I can work on a fix for this if nobody is already doing so.
It may also make sense to add the topic-sqlite3 and stdlib labels.

Sure! I don't think anyone is actively working on it, feel free to to correct me if I'm wrong :)

[vstinner]

With the fix, the example now fails with:

Traceback (most recent call last):
  File "/home/vstinner/python/main/x.py", line 3, in <module>
    del db.row_factory
        ^^^^^^^^^^^^^^
AttributeError: cannot delete row_factory attribute

[encukou]

Is there any reasonable user code that gets this error, and without the fix it didn't segfault [edit: or raise] later?

[vstinner]

Is there any reasonable user code that gets this error, and without the fix it didn't segfault later?

I don't think that it's possible to do anything useful without row_factory or text_factory attribute.

After del db.row_factory, any db.execute() call does crash. So it makes the connection unusable.

For text_factory, any request returning a text column does fail with an internal error (SystemError):

import sqlite3
db = sqlite3.connect(":memory:")
del db.text_factory
row = db.execute("SELECT 'a'")
print(row.fetchone())

Output without this fix:

Traceback (most recent call last):
  File "/home/vstinner/python/main/x.py", line 5, in <module>
    print(row.fetchone())
          ~~~~~~~~~~~~^^
SystemError: null argument to internal routine