[pgpool-committers: 4854] pgpool: Fix accessing already freed data in extended query.

[Tatsuo Ishii]

Fix accessing already freed data in extended query.

When previous_message was set and accessed later on, it looked into
already freed data. This is because read_kind_from_backend() set the
pointer to the previous message in session context, and then released
the memory at the end of the function. No report from fields so far. I
just found this while testing Pgpool-II.

To fix this, store the previous message in the session context, rather
than storing the pointer. Also have a flag in the session context to
indicate whether a previous message is actually stored or not.

All the API for previous message has not been changed.

Branch
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V3_7_STABLE

Details
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https://git.postgresql.org/gitweb?p=pgpool2.git;a=commitdiff;h=341bf8ec0edcc813372246b4886cbb4304f7fa84

Modified Files
--------------
src/context/pool_session_context.c         | 13 +++++++++----
src/include/context/pool_session_context.h |  7 +++++--
2 files changed, 14 insertions(+), 6 deletions(-)