Re: [PATCH] Replace debug-only Asserts with runtime checks in logical replication apply worker

On Sun, May 17, 2026 at 02:30:00AM +0400, Varik Matevosyan wrote:
> The attached patch replaces three debug-only Asserts with runtime
> ereport(ERROR, ERRCODE_PROTOCOL_VIOLATION) checks in the logical
> replication apply worker (worker.c). These guard against a mismatch
> between the column count in the RELATION message and the count in a
> subsequent INSERT/UPDATE/DELETE tuple message.
>
> A publisher can send a RELATION claiming N columns and
> an INSERT claiming M < N columns, causing the subscriber
> to index past the end of the tuple's colvalues[]/colstatus[] arrays.
>
> I believe this is more of a correctness fix than a security issue as
> the attacker needs replication privileges, and in my testing I was not
> able to trigger a SIGSEGV, the OOB read landed on heap bytes that
> happened to not cause a crash.
>
> P.S: After a security review from Noah, I'm reporting this as a bug.

Pushed (bf7d19b). Thank you.