An issue was found in the way Linux kernel implemented software flush of the Count Cache (indirect branch cache) and Link (Return Address) Stack on 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.
Created kernel tracking bugs for this issue:
Affects: fedora-all [bug 1777826]
This issue has been addressed in the following products:
Red Hat Enterprise Linux 7
Via RHSA-2020:0174 https://access.redhat.com/errata/RHSA-2020:0174
This bug is now closed. Further updates for individual products will be reflected on the CVE page(s):
This issue affects versions of the kernel package as shipped with Red Hat Enterprise Linux 6, 7 and 8. Future kernel updates for Red Hat Enterprise Linux 6, 7 and 8 may address this issue.
This issue does not affect the version of the kernel package as shipped with Red Hat Enterprise MRG 2.