[pgpool-committers: 6158] pgpool: Fix segfault in certain case.

[Tatsuo Ishii]

Fix segfault in certain case.

The scenario is something like:

1) a named statement is created.
2) DEALLOCATE removes it.
3) an erroneous query is executed.

In #2, "sent message" for the named statement is removed but
"uncompleted_message" is left. Then after #3, in ReadyForQuery()
uncompleted_message is added and removed. However, storage for the
uncompleted_message has been already freed in #2, and it causes a
segfault.

Fix is, in SimpleQuery() set NULL to uncompleted_message if it's not
PREPARE command so that ReadyForQuery() does not try to remove the
already removed message.

Per bug 546.

Here is a minimum test case.

'P'     "_plan0x7f2d465db530"   "SELECT 1"      0
'S'
'Y'
'Q'     "DEALLOCATE _plan0x7f2d465db530"
'Y'
'Q'     "CREATE INDEX users_auth_id_index ON non_existing_table ( auth_id )"
'Y'
'X'

Branch
------
V3_6_STABLE

Details
-------
https://git.postgresql.org/gitweb?p=pgpool2.git;a=commitdiff;h=1a9c291b6871a440d769033ff66f9ed6cd7ca189

Modified Files
--------------
src/protocol/pool_proto_modules.c | 2 ++
1 file changed, 2 insertions(+)