s390/decompressor: specify __decompress() buf len to avoid overflow
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 v6.1.13 by commit f1eb22d0ff064ad458b3b1a1eaa84ac3996206c2. For more details please see the references link.