Fix null pointer dereference in "\c" psql command.

The psql crash happened when no current connection existed.  (The second
new check is optional given today's undocumented NULL argument handling
in PQhost() etc.)  Back-patch to 9.0 (all supported versions).

diff --git a/src/bin/psql/command.c b/src/bin/psql/command.c
index 38253fa09886e9c0950372d02ac5ec12e6dbda23..467e34b1ffcd84a07f3b27a9437cb9b409a02c5c 100644 (file)
--- a/src/bin/psql/command.c
+++ b/src/bin/psql/command.c
@@ -1641,7 +1641,8 @@ do_connect(char *dbname, char *user, char *host, char *port)
     * positional syntax.
     */
    keep_password =
-       ((strcmp(user, PQuser(o_conn)) == 0) &&
+       (o_conn &&
+        (strcmp(user, PQuser(o_conn)) == 0) &&
         (!host || strcmp(host, PQhost(o_conn)) == 0) &&
         (strcmp(port, PQport(o_conn)) == 0) &&
         !has_connection_string);
@@ -1768,7 +1769,8 @@ do_connect(char *dbname, char *user, char *host, char *port)
    /* Tell the user about the new connection */
    if (!pset.quiet)
    {
-       if (param_is_newly_set(PQhost(o_conn), PQhost(pset.db)) ||
+       if (!o_conn ||
+           param_is_newly_set(PQhost(o_conn), PQhost(pset.db)) ||
            param_is_newly_set(PQport(o_conn), PQport(pset.db)))
        {
            char       *host = PQhost(pset.db);