Re: Tuple sort is broken. It crashes on simple test.

Peter Geoghegan <pg@heroku.com>

From: Peter Geoghegan <pg@heroku.com>

To: Michael Paquier <michael.paquier@gmail.com>

Cc: Mithun Cy <mithun.cy@enterprisedb.com>, pgsql-hackers <pgsql-hackers@postgresql.org>, Robert Haas <robertmhaas@gmail.com>, Heikki Linnakangas <hlinnaka@iki.fi>

Date: 2017-01-16T18:24:20Z

Lists: pgsql-hackers

Attachments

0001-Fix-NULL-pointer-dereference-in-tuplesort.c.patch (text/x-patch) patch 0001
(unnamed) (text/plain)

On Mon, Jan 16, 2017 at 3:48 AM, Michael Paquier
<michael.paquier@gmail.com> wrote:
> Indeed. It crashes for me immediately by adding an ORDER BY:
> select count(distinct t) from seq_tab order by 1;

The problem was that one particular call to the macro
RELEASE_SLAB_SLOT() happened to lack a test-for-NULL-argument needed
by pass-by-value datum cases. The other two RELEASE_SLAB_SLOT() calls
already have such a check.

Attached patch fixes the bug.

-- 
Peter Geoghegan

Commits

Fix NULL pointer dereference in tuplesort.c.
- 4e46c97fde42 10.0 landed
Change the way pre-reading in external sort's merge phase works.
- e94568ecc10f 10.0 cited