acpid: denial of service

It was reported that acpid opened the UNIX socket that informs unprivileged processes about acpi evens in blocking mode. If an unprivileged process were to stop reading data from the socket, then after some time the socket queue fills up which would then lead to a hang of the privileged acpid daemon. The daemon will hang until the socket peer process read some portion of the queued data or the peer process exits or is killed.