The asynchronous I/O facility in 4.4 BSD kernel does not check user credentials when setting the recipient of I/O notification, which allow…

The asynchronous I/O facility in 4.4 BSD kernel does not check user credentials when setting the recipient of I/O notification, which allows local users to cause a denial of service by using certain ioctl and fcntl calls to cause the signal to be sent to an arbitrary process ID.