[CentOS-devel] RSB filling is enabled for CentOS 7 Kernel?

Tue Oct 30 23:07:23 UTC 2018
Akemi Yagi <amyagi at gmail.com>

On Tue, Oct 30, 2018 at 5:06 AM Veetil, Vyshnav
<Vyshnav.Veetil at harman.com> wrote:

> We ran the spectre meltdown checker tool provided by: https://github.com/speed47/spectre-meltdown-checker.
> And it says that we are still vulnerable to variant #2 since RSB filling is not enabled in our kernel
> When we googled, the following bugzilla from RH suggests that it is enabled by default:
> https://bugzilla.redhat.com/show_bug.cg ... 2018-15572
> When I was checking the  source code of the latest CentOS kernel ,i don't see this feature flag set anywhere - X86_FEATURE_RSB_CTXSW.
> Could you please tell us ,If the Latest CentOS kernel supports RSB filling or not ?!

According to https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2018-15572
(see comment 4),

"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."

And comment 8 explains why.