From: Amit Langote <amitlan@postgresql.org>
To: pgsql-committers@lists.postgresql.org
Subject: pgsql: Fix expression list handling in ATExecAttachPartition()
Date: Thu, 03 Oct 2024 03:01:45 +0000
Message-ID: <E1swC64-001wRs-P0@gemulon.postgresql.org> (raw)
Fix expression list handling in ATExecAttachPartition()
This commit addresses two issues related to the manipulation of the
partition constraint expression list in ATExecAttachPartition().
First, the current use of list_concat() to combine the partition's
constraint (retrieved via get_qual_from_partbound()) with the parent
table’s partition constraint can lead to memory safety issues. After
calling list_concat(), the original constraint (partBoundConstraint)
might no longer be safe to access, as list_concat() may free or modify
it.
Second, there's a logical error in constructing the constraint for
validating against the default partition. The current approach
incorrectly includes a negated version of the parent table's partition
constraint, which is redundant, as it always evaluates to false for
rows in the default partition.
To resolve these issues, list_concat() is replaced with
list_concat_copy(), ensuring that partBoundConstraint remains unchanged
and can be safely reused when constructing the validation constraint
for the default partition.
This fix is not applied to back-branches, as there is no live bug and
the issue has not caused any reported problems in practice.
Nitin Jadhav posted a patch to address the memory safety issue, but I
decided to follow Alvaro Herrera's suggestion from the initial
discussion, as it allows us to fix both the memory safety and logical
issues.
Reported-by: Andres Freund <andres@anarazel.de>
Reported-by: Nitin Jadhav <nitinjadhavpostgres@gmail.com>
Reviewed-by: Junwang Zhao <zhjwpku@gmail.com>
Discussion: https://postgr.es/m/20231115165737.zeulb575cgrbqo74@awork3.anarazel.de
Discussion: https://postgr.es/m/CAMm1aWbmYHM3bqtjyMQ-a+4Ub=dgsb_2E3_up2cn=UGdHNrGTg@mail.gmail.com
Branch
------
master
Details
-------
https://git.postgresql.org/pg/commitdiff/babb3993dbe9c805c1d29fa275a5e8f4c2b40922
Modified Files
--------------
src/backend/commands/tablecmds.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)
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To: pgsql-committers@postgresql.org
Cc: amitlan@postgresql.org, pgsql-committers@lists.postgresql.org
Subject: Re: pgsql: Fix expression list handling in ATExecAttachPartition()
In-Reply-To: <E1swC64-001wRs-P0@gemulon.postgresql.org>
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