Fix replication delay worker segfault when application_name is an empty string.

The process calls do_query() to obtain the query result against
pg_stat_replication_view.  If user sets application_name to an empty
string, the result data row packet length will be 0. However
do_query() did not consider the length == 0 case, which resulted in
giving NULL pointer to strcmp() which is called from the worker
process. That means the bug is not specific to this case (a new
feature added in Pgpool-II 4.1) but it potentially affects many other
places where do_query() gets called, although it had not been reported
in the field. So this fix should be applied to all supported branches.

Per bug 565.

diff --git a/src/protocol/pool_process_query.c b/src/protocol/pool_process_query.c
index 66dbb0aa19ddccfb594ef117afd9cc12e58bd73a..09a2c28afc3ded3094f7ba9e9a79a24d42bc4221 100644 (file)
--- a/src/protocol/pool_process_query.c
+++ b/src/protocol/pool_process_query.c
@@ -2747,7 +2747,7 @@ void do_query(POOL_CONNECTION *backend, char *query, POOL_SELECT_RESULT **result
 
                                                        res->nullflags[num_data] = len;
 
-                                                       if (len > 0)    /* NOT NULL? */
+                                                       if (len >= 0)   /* NOT NULL? */
                                                        {
                                                                res->data[num_data] = palloc(len + 1);
                                                                memcpy(res->data[num_data], p, len);
@@ -2770,7 +2770,7 @@ void do_query(POOL_CONNECTION *backend, char *query, POOL_SELECT_RESULT **result
 
                                                                res->nullflags[num_data] = len;
 
-                                                               if (len > 0)
+                                                               if (len >= 0)
                                                                {
                                                                        p = pool_read2(backend, len);
                                                                        res->data[num_data] = palloc(len + 1);