GSD-2022-1001367 jfs: prevent NULL deref in diFree

jfs: prevent NULL deref in diFree This is an automated ID intended to aid in discovery of potential security vulnerabilities. The actual impact and attack plausibility have not yet been proven. This ID is fixed in Linux Kernel version v5.16.20 by commit ffe1d40aec3f6f8cc620369ba07eb5e9bd449d85. F...