Re: Fix use of variable after pfree

Amit Kapila <amit.kapila16@gmail.com>

From: Amit Kapila <amit.kapila16@gmail.com>
To: Shlok Kyal <shlok.kyal.oss@gmail.com>
Cc: PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2025-09-02T07:42:49Z
Lists: pgsql-hackers
On Tue, Sep 2, 2025 at 1:02 PM Shlok Kyal <shlok.kyal.oss@gmail.com> wrote:
>
> Hi,
>
> While going through the code of the slot sync worker, I found that in
> functions ReplSlotSyncWorkerMain and pg_sync_replication_slots the
> variable app_name.data is being used after it is freed.
>
> We can get logs as following:
> 2025-09-02 12:26:48.520 IST [3908359] ERROR:  synchronization worker
> "" could not connect to the primary server: connection to server at
> "localhost" (127.0.0.1), port 5432 failed: Connection refused
>         Is the server running on that host and accepting TCP/IP connections?
>
> I have moved the pfree(app_data.name) after its usage.
>
> This change was introduced in PG_18.
> The patch applies in the HEAD and REL_18_STABLE branches.
>

Thanks for the patch. It looks good to me. I'll take care of it.

-- 
With Regards,
Amit Kapila.



Commits

  1. Fix use-after-free issue in slot synchronization.