Service hang via blocking FIFO report read

Improper input validation in Canonical Apport allows local users to hang crash processing by substituting a FIFO for a report file. The data/apport handler opens an attacker-controlled .crash report path with a blocking read and waits indefinitely when the path is a FIFO without a writer. Local low-privileged access and control of a report pathname are required; alone the flaw interrupts crash handling, while a public exploit chains the stall with separate flaws for privilege escalation.