From: Tatsuo Ishii <ishii@postgresql.org>
Date: Tue, 23 Jan 2018 23:01:22 +0000 (+0900)
Subject: Fix segfault when %a is in log_line_prefix and debug message is on.
X-Git-Tag: V4_0_0_ALPHA1~149
X-Git-Url: http://git.postgresql.org/gitweb/static/gitweb.js?a=commitdiff_plain;h=e6b4a1ec58ee3d0ca19957f19d643e9a867c26b9;p=pgpool2.git

Fix segfault when %a is in log_line_prefix and debug message is on.

log_line_prefix() gets called to create a log line prefix string. If
"%a" is specified in "log_line_prefix" parameter, log_line_prefix()
calls MASTER_CONNECTION macro, which calls
pool_virtual_master_db_node_id(), which calls ereport(), which calls
log_line_prefix() if debug message is on. This leads to an infinite
recursion and a segfault. Fix is, calling MASTER_NODE_ID macro instead
of MASTER_CONNECTION macro.

Per bug 376.
---

diff --git a/src/utils/error/elog.c b/src/utils/error/elog.c
index cb3b403af..114083612 100644
--- a/src/utils/error/elog.c
+++ b/src/utils/error/elog.c
@@ -43,7 +43,7 @@
  * overflow.)
  *
  *
- * Portions Copyright (c) 2003-2015, PgPool Global Development Group
+ * Portions Copyright (c) 2003-2018, PgPool Global Development Group
  * Portions Copyright (c) 1996-2015, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
@@ -1997,7 +1997,13 @@ log_line_prefix(StringInfo buf, const char *line_prefix, ErrorData *edata)
 		{
 			case 'a':	/* application name */
 			{
-				StartupPacket *sp = session? MASTER_CONNECTION(session->backend)->sp : NULL ;
+
+				/*
+				 * Do not use MASTER_CONNECTION macro here since it calls
+				 * pool_virtual_master_db_node_id() which eventually calls
+				 * ereport() if operated in DEBUG mode.
+				 */
+				StartupPacket *sp = session? (session->backend->slots[REAL_MASTER_NODE_ID])->sp : NULL ;
 				const char *appname = sp? sp->application_name : "[No Connection]";
 				if (appname == NULL || *appname == '\0')
 					appname = "[unknown]";