CVE-2021-47356

Description

In the Linux kernel, the following vulnerability has been resolved: mISDN: fix possible use-after-free in HFC_cleanup() This modules remove path calls del_timer(). However, that function does not wait until the timer handler finishes. This means that the timer handler may still be running after the drivers remove function has finished, which would result in a use-after-free. Fix by calling del_timer_sync(), which makes sure the timer handler has finished, and unable to re-schedule itself.