In the Linux kernel, the following vulnerability has been resolved: ax25: fix use-after-free bugs caused by ax25dsdeltimer When the ax25 device is detaching, the ax25devdevicedown() calls ax25dsdeltimer() to cleanup the slavetimer. When the timer handler is running, the ax25dsdeltimer() that calls deltimer() in it will return directly. As a result, the use-after-free bugs could happen, one of the scenarios is shown below: (Thread 1) | (Thread 2) | ax25dstimeout() ax25devdevicedown() | ax25dsdeltimer() | deltimer() | ax25devput() //FREE | | ax25dev-> //USE In order to mitigate bugs, when the device is detaching, use timershutdownsync() to stop the timer.