postgres_fdw and dblink should check if backend has MyProcPort

before checking ->has_scram_keys.  MyProcPort is NULL in background
workers.  So this could crash for example if a background worker
accessed a suitable configured foreign table.

Author: Alexander Pyhalov <a.pyhalov@postgrespro.ru>
Reviewed-by: Peter Eisentraut <peter@eisentraut.org>
Reviewed-by: Matheus Alcantara <matheusssilv97@gmail.com>
Discussion: https://www.postgresql.org/message-id/flat/27b29a35-9b96-46a9-bc1a-914140869dac%40gmail.com

contrib/dblink/dblink.c

@@ -2643,7 +2643,7 @@ dblink_connstr_has_required_scram_options(const char *connstr)
 		PQconninfoFree(options);
 	}
 
-	has_scram_keys = has_scram_client_key && has_scram_server_key && MyProcPort->has_scram_keys;
+	has_scram_keys = has_scram_client_key && has_scram_server_key && MyProcPort != NULL && MyProcPort->has_scram_keys;
 
 	return (has_scram_keys && has_require_auth);
 }
@@ -2676,7 +2676,7 @@ dblink_security_check(PGconn *conn, const char *connname, const char *connstr)
 	 * only added if UseScramPassthrough is set, and the user is not allowed
 	 * to add the SCRAM keys on fdw and user mapping options.
 	 */
-	if (MyProcPort->has_scram_keys && dblink_connstr_has_required_scram_options(connstr))
+	if (MyProcPort != NULL && MyProcPort->has_scram_keys && dblink_connstr_has_required_scram_options(connstr))
 		return;
 
 #ifdef ENABLE_GSS
@@ -2749,7 +2749,7 @@ dblink_connstr_check(const char *connstr)
 	if (dblink_connstr_has_pw(connstr))
 		return;
 
-	if (MyProcPort->has_scram_keys && dblink_connstr_has_required_scram_options(connstr))
+	if (MyProcPort != NULL && MyProcPort->has_scram_keys && dblink_connstr_has_required_scram_options(connstr))
 		return;
 
 #ifdef ENABLE_GSS
@@ -2896,7 +2896,7 @@ get_connect_string(const char *servername)
 		 * the user overwrites these options we can ereport on
 		 * dblink_connstr_check and dblink_security_check.
 		 */
-		if (MyProcPort->has_scram_keys && UseScramPassthrough(foreign_server, user_mapping))
+		if (MyProcPort != NULL && MyProcPort->has_scram_keys && UseScramPassthrough(foreign_server, user_mapping))
 			appendSCRAMKeysInfo(&buf);
 
 		foreach(cell, fdw->options)

contrib/postgres_fdw/connection.c

@@ -464,7 +464,7 @@ pgfdw_security_check(const char **keywords, const char **values, UserMapping *us
 	 * assume that UseScramPassthrough is also true since SCRAM options are
 	 * only set when UseScramPassthrough is enabled.
 	 */
-	if (MyProcPort->has_scram_keys && pgfdw_has_required_scram_options(keywords, values))
+	if (MyProcPort != NULL && MyProcPort->has_scram_keys && pgfdw_has_required_scram_options(keywords, values))
 		return;
 
 	ereport(ERROR,
@@ -570,7 +570,7 @@ connect_pg_server(ForeignServer *server, UserMapping *user)
 		n++;
 
 		/* Add required SCRAM pass-through connection options if it's enabled. */
-		if (MyProcPort->has_scram_keys && UseScramPassthrough(server, user))
+		if (MyProcPort != NULL && MyProcPort->has_scram_keys && UseScramPassthrough(server, user))
 		{
 			int			len;
 			int			encoded_len;
@@ -748,7 +748,7 @@ check_conn_params(const char **keywords, const char **values, UserMapping *user)
 	 * assume that UseScramPassthrough is also true since SCRAM options are
 	 * only set when UseScramPassthrough is enabled.
 	 */
-	if (MyProcPort->has_scram_keys && pgfdw_has_required_scram_options(keywords, values))
+	if (MyProcPort != NULL && MyProcPort->has_scram_keys && pgfdw_has_required_scram_options(keywords, values))
 		return;
 
 	ereport(ERROR,
@@ -2559,7 +2559,7 @@ pgfdw_has_required_scram_options(const char **keywords, const char **values)
 		}
 	}
 
-	has_scram_keys = has_scram_client_key && has_scram_server_key && MyProcPort->has_scram_keys;
+	has_scram_keys = has_scram_client_key && has_scram_server_key && MyProcPort != NULL && MyProcPort->has_scram_keys;
 
 	return (has_scram_keys && has_require_auth);
 }