Re: [PATCH 5.10 191/717] memstick: fix a double-free bug in memstick_check

Hi!

From: Qinglang Miao miaoqinglang@huawei.com

[ Upstream commit e3e9ced5c93803d5b2ea1942c4bf0192622531d6 ]

kfree(host->card) has been called in put_device so that another kfree would raise cause a double-free bug.

+++ b/drivers/memstick/core/memstick.c @@ -468,7 +468,6 @@ static void memstick_check(struct work_struct *work) host->card = card; if (device_register(&card->dev)) { put_device(&card->dev);

• 		kfree(host->card);
  	host->card = NULL;
  }
  

Does the host->card = NULL need to be removed, too (and following code refactored)? put_device() needs that pointer to be able to free it and it can do so asynchronously.

This will cause crashes; they should be easy to reproduce with CONFIG_DEBUG_KOBJECT_RELEASE due to delay in kobject_release() AFAICT.

Best regards, Pavel