Message-ID: <gh-postgresql-interfaces-psqlodbc-190@github.com>
From: "davecramer (@davecramer)" <noreply+davecramer@github.com>
To: "postgresql-interfaces/psqlodbc" <noreply+postgresql-interfaces-psqlodbc@github.com>
Date: Fri, 22 May 2026 14:06:21 +0000
Subject: [postgresql-interfaces/psqlodbc] PR #190: Fix double-free / heap corruption during SQLDisconnect cleanup (#189)
List-Id: <gh-postgresql-interfaces-psqlodbc.github.com>
X-GitHub-Author-Id: 406518
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X-GitHub-Issue: 190
X-GitHub-Repo: postgresql-interfaces/psqlodbc
X-GitHub-State: merged
X-GitHub-Type: pull_request
X-GitHub-Url: https://github.com/postgresql-interfaces/psqlodbc/pull/190
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CC_cleanup() was freeing statement and descriptor objects via SC_Destructor(), but the ODBC Driver Manager still held handles to them. When the DM later called SQLFreeStmt(SQL_DROP) via SQLFreeHandle(), the driver dereferenced freed memory, causing the double-free detected by Application Verifier with Page Heap enabled.

Fix by detaching statements/descriptors in CC_cleanup() without freeing them. The DM will free them later through the normal SQLFreeHandle path. Also allow SQLFreeStmt(SQL_DROP) to proceed when hdbc is NULL (the expected state after disconnect), and remove misleading error-return logic in SC_Destructor that reported failure after already freeing.