dm integrity: Fix UAF in dm_integrity_dtr()

Dm_integrity also has the same UAF problem when dm_resume()
and dm_destroy() are concurrent.

Therefore, cancelling timer again in dm_integrity_dtr().

Cc: stable@vger.kernel.org
Fixes: 7eada909 ("dm: add integrity target")
Signed-off-by: Luo Meng <luomeng12@huawei.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>

drivers/md/dm-integrity.c

@@ -4558,6 +4558,8 @@ static void dm_integrity_dtr(struct dm_target *ti)
 	BUG_ON(!RB_EMPTY_ROOT(&ic->in_progress));
 	BUG_ON(!list_empty(&ic->wait_list));
 
+	if (ic->mode == 'B')
+		cancel_delayed_work_sync(&ic->bitmap_flush_work);
 	if (ic->metadata_wq)
 		destroy_workqueue(ic->metadata_wq);
 	if (ic->wait_wq)