Re: BUG #18830: ExecInitMerge Segfault on MERGE

From: Amit Langote <amitlangote09(at)gmail(dot)com>
To: Tender Wang <tndrwang(at)gmail(dot)com>
Cc: tharakan(at)gmail(dot)com, pgsql-bugs(at)lists(dot)postgresql(dot)org
Subject: Re: BUG #18830: ExecInitMerge Segfault on MERGE
Date: 2025-03-04 11:51:25
Message-ID: CA+HiwqH98Fvpw-OQYz86aDhznhTaxtVq-Etdnq3eFts+pXcFBw@mail.gmail.com
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On Mon, Mar 3, 2025 at 9:16 PM Tender Wang <tndrwang(at)gmail(dot)com> wrote:
> nrels = list_length(resultRelations);
> ...
> mtstate->resultRelInfo = (ResultRelInfo *)
> palloc(nrels * sizeof(ResultRelInfo));
>
> The memory of mtstate->resultRelInfo point to is undefined. When we access its memory in ExecInitMerge(),

This needs to be fixed saparately.

> relationDesc = RelationGetDescr(resultRelInfo->ri_RelationDesc);
>
> crash happened.

Do you have a case where this access to undefined
ModifyTableState.resultRelInfo occurs? I would have thought that it
should not happen.

--
Thanks, Amit Langote

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