Re: Use of uninitialized variables in ExecFindPartition() for parent partition without leaves (HEAD only)

From: Amit Langote <Langote_Amit_f8(at)lab(dot)ntt(dot)co(dot)jp>
To: Michael Paquier <michael(dot)paquier(at)gmail(dot)com>, PostgreSQL mailing lists <pgsql-hackers(at)postgresql(dot)org>
Cc: Amit Langote <amitlangote09(at)gmail(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>
Subject: Re: Use of uninitialized variables in ExecFindPartition() for parent partition without leaves (HEAD only)
Date: 2017-11-30 01:11:09
Message-ID: e0c4420d-5f7b-16fa-6b58-0a2e4a14d1e0@lab.ntt.co.jp
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Hi Michael.

On 2017/11/30 9:07, Michael Paquier wrote:
> Hi all,
>
> Since commit 4e5fe9ad (committer Robert Haas and author Amit Langote),
> coverity has been complaining that the new code of ExecFindPartition()
> may use a set of values and isnull values which never get initialized.
> This is a state which can be easily reached with the following SQLs of
> a parent partition with no children:
> create table parent_tab (a int) partition by list ((a+0));
> insert into parent_tab values (1);
>
> The mistake is visibly that FormPartitionKeyDatum() should be called
> even for a root partition, initializing the fields of isnull and
> values on the way. That's actually what happens in execMain.c's
> ExecFindPartition() if you look at REL_10_STABLE. So the answer would
> be to move a bit down the quick exit code. Attached is a patch.
>
> Amit, that's your code. What do you think?

Thanks for the report. That's clearly a bug. :-(

Your patch seems enough to fix it. I added a test and expanded the
comment a bit in the attached updated version.

Thanks,
Amit

Attachment Content-Type Size
exec-partition-quickexit-v2.patch text/plain 2.7 KB

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