An issue was found in the way modern x86 microprocessor designs have implemented speculative execution of instructions (a commonly used performance optimisation) and prediction of return addresses via Return Stack Buffer(RSB). RSB is a small on chip structure that holds list of return addresses, used to predict function return addresses.
An unprivileged attacker could use this flaw to cross the syscall or process boundary and read privileged memory by conducting targeted cache side-channel attacks.
Name: Giorgi Maisuradze (Saarland University), Christian Rossow (Saarland University), Nael Abu-Ghazaleh (University of California), Esmaiel Mohammadian Koruyeh (University of California), Khaled Khasawneh (University of California), Chengyu Song (University of California)
Created kernel tracking bugs for this issue:
Affects: fedora-all [bug 1616246]
This is fixed for Fedora with the 4.17.14-202 stable update kernels.
*** Bug 1619446 has been marked as a duplicate of this bug. ***
@Prasad: Could you please explain why this issue does not affect the RHEL 5, 6, 7 kernels?
(In reply to Karsten Weiss from comment #7)
> @Prasad: Could you please explain why this issue does not affect the RHEL 5,
> 6, 7 kernels?
SpectreRSB attack requires that kernel does not fill Return Stack Buffer (RSB) upon context switch and/or VM entry/exit. And SMEP is disabled.
RHEL-5 fills RSB when SMEP is enabled. Whereas RHEL 6, 7 kernels do it unconditionally whether SMEP is on or off. Upstream patch above does the same.
This issue affects the version of the kernel package as shipped with Red Hat Enterprise Linux 5.
This issue does not affect the versions of the kernel package as shipped with Red Hat Enterprise Linux 6, 7, and Red Hat Enterprise MRG 2.
Red Hat Enterprise Linux 5 is now in Production 3 Phase of the support and maintenance life cycle. This has been rated as having Moderate security impact and is not currently planned to be addressed in future updates. For additional information, refer to the Red Hat Enterprise Linux Life Cycle: https://access.redhat.com/support/policy/updates/errata/.
This bug is now closed. Further updates for individual products will be reflected on the CVE page(s):