CVE-2019-18660

A flaw was found in the way the Linux kernel implemented a software flush of the Count Cache (indirect branch cache) and Link (Return Address) Stack on the PowerPC platform. The flushing of these structures helps to prevent SpectreRSB like attacks which may leak information from one user process to another. An unprivileged user could use this flaw to cross the syscall or process boundary and read privileged memory by conducting targeted cache side-channel attacks.