proc/vmcore: fix clearing user buffer by properly using clear_user()
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 v4.19.219 by commit 9ef384ed300d1bcfb23d0ab0b487d544444d4b52, it was introduced in version v3.0 by commit 997c136f518c5debd63847e78e2a8694f56dcf90. For more details please see the references link.