The MySQL 5.6.42 release contains the following InnoDB changes:
Bug#26876608 MYSQL CRASH:CACHE_POLICY=CACHING INNODB_ONLY & SET GLOBAL INNODB_API_TRX_LEVEL=1: not applicable, because the InnoDB Memcached plugin was never enabled in MariaDB, and the last traces of it were removed in
MDEV-12050 in MariaDB Server 10.2.
Bug #27545888 MYSQLD CRASHES WHEN RENAMING AN INNODB TABLE WITH FOREIGN KEY AND FULLTEXT KEY was filed as
Bug #27753193 ASSERTION `PREBUILT->TRX->ERROR_KEY_NUM < HA_ALTER_INFO->KEY_COUNT' comes with a test case that does not fail in MariaDB. There was a follow-up code fix.
A commit not mentioning any bug number is changing a PERFORMANCE_SCHEMA call for creating temporary files for ALTER TABLE…ALGORITHM=INPLACE. This was filed as