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GeezerVison is showing github.com — Guard iAttachment.detach() against an already-released interface (1.x backport of #69) by aminghadersohi · Pull Request #78 · FirebirdSQL/python3-driver

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aminghadersohi commented Sep 26, 2026

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Backport of the #69 fix (#72, merged to master on 2026-05-21) to release-1.x. Fixes #77.

On 1.x, the v5 iAttachment.detach() override calls the native detach without the if self._refcnt: guard that iAttachment_v4.detach() has. When the garbage collector finalizes a connection that was never closed, the interface can already be released, and Connection.__del__ then detaches freed memory, which segfaults the process.

The change restores the guard, the same code as on master.

Verification against Firebird 5.0.3, CPython 3.11.15, Linux x86_64, with firebird-base 1.8.0, using the reproduction script in #77 (100 abandoned connections, each followed by gc.collect()):

release-1.x (1.10.11): segfault in interfaces.py detach in 3 of 3 runs (exit 139)
with this change: completed in 3 of 3 runs (exit 0)

The master regression test (tests/test_issues.py::test_issue_69_gc_of_abandoned_connection) relies on the pytest layout, which release-1.x does not have, so it is not ported here. The standalone script in #77 reproduces the crash on this branch.

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          Guard iAttachment.detach() against an already-released interface (1.x)

375055e

Backport of the FirebirdSQL#69 fix (FirebirdSQL#72) to release-1.x. During cyclic garbage
collection the iAttachment's own iReferenceCounted.__del__ may run release()
before Connection.__del__ calls detach(); the v5 detach() override then
dereferenced freed memory and segfaulted. Restore the if self._refcnt guard
that iAttachment_v4.detach() already has.

Fixes FirebirdSQL#77.

aminghadersohi mentioned this pull request

Sep 26, 2026

1.10.x: segfault when garbage-collecting an unclosed connection (#69 not fixed on release-1.x) #77

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pcisar merged commit e091764 into FirebirdSQL:release-1.x

Oct 7, 2026

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