Skip site navigation (1) Skip section navigation (2)

pgsql: Add missing buffer lock acquisition in GetTupleForTrigger().

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: pgsql-committers(at)postgresql(dot)org
Subject: pgsql: Add missing buffer lock acquisition in GetTupleForTrigger().
Date: 2012-11-30 18:56:56
Message-ID: E1TeVlg-000334-7K@gemulon.postgresql.org (view raw or flat)
Thread:
Lists: pgsql-committers
Add missing buffer lock acquisition in GetTupleForTrigger().

If we had not been holding buffer pin continuously since the tuple was
initially fetched by the UPDATE or DELETE query, it would be possible for
VACUUM or a page-prune operation to move the tuple while we're trying to
copy it.  This would result in a garbage "old" tuple value being passed to
an AFTER ROW UPDATE or AFTER ROW DELETE trigger.  The preconditions for
this are somewhat improbable, and the timing constraints are very tight;
so it's not so surprising that this hasn't been reported from the field,
even though the bug has been there a long time.

Problem found by Andres Freund.  Back-patch to all active branches.

Branch
------
master

Details
-------
http://git.postgresql.org/pg/commitdiff/da63fec7dbb0c459aa0f8753a3d30a3a6cd3d73f

Modified Files
--------------
src/backend/commands/trigger.c |   12 ++++++++++++
1 files changed, 12 insertions(+), 0 deletions(-)


pgsql-committers by date

Next:From: Bruce MomjianDate: 2012-11-30 19:50:00
Subject: pgsql: Move long_options structures to the top of main() functions,for
Previous:From: Andrew DunstanDate: 2012-11-30 15:55:18
Subject: pgsql: Clean environment for pg_upgrade test.

Privacy Policy | About PostgreSQL
Copyright © 1996-2014 The PostgreSQL Global Development Group