[PATCH 4.4 30/57] mqueue: fix a use-after-free in sys_mq_notify()

4.4-stable review patch. If anyone has any objections, please let me know. -- From: Cong Wang commit f991af3daabaecff34684fd51fac80319d1baad1 upstream. The retry logic for netlink_attachskb() inside sys_mq_notify() is nasty and vulnerable: 1) The

[PATCH 4.4 30/57] mqueue: fix a use-after-free in sys_mq_notify()

4.4-stable review patch. If anyone has any objections, please let me know. -- From: Cong Wang commit f991af3daabaecff34684fd51fac80319d1baad1 upstream. The retry logic for netlink_attachskb() inside sys_mq_notify() is nasty and vulnerable: 1) The sock refcnt is already