exfat: check if cluster num is valid
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 v5.15.45 by commit c504167adc3248095a905fa0700a9693897cb5ed, it was introduced in version v5.7 by commit 1e49a94cf707204b66a3fb242f2814712c941f52. For more details please see the references link.