gcc version 4.8.5 20150623 / Meltdown and/or Spectre vulnerabilities

[Vassilena Treneva]

Thank you!

Which the the knowledge base article that you would recommend I read to get
a bit more familiar with this topic?

On Fri, Jun 15, 2018 at 6:47 PM Jeff Law <law@redhat.com> wrote:

> On 06/15/2018 09:34 AM, Vassilena Treneva wrote:
> > Many thanks for your quick answers.
> >
> > Perhaps silly questions but:
> >
> > 1) is there a way to check if the version that I am using really
> > contains those patches?
> > Running on Red Hat Enterprise Linux Server release 7.2 (Maipo) with gcc
> > (GCC) 4.8.5 20150623 (Red Hat 4.8.5-4).
> Use RPM to get the precise version of the package you are using rather
> than "gcc -v".  "rpm -qi gcc"
>
> You'll be looking for a release like 4.el7_2.1
>
> >
> > 2) Does that mean that to avoid Spectre v2 I can add  -mindirect-branch
> > compiler option? Are there other options in place?
> I would suggest you read the knowledge base article on the subject.  In
> general we do not recommend compiling user space code with spectre
> mitigations.  It is unnecessary.
>
> THe kernel and kernel modules provided by Red Hat are already build with
> the proper mitigations.   Out of tree kernel modules that use the kbuild
> system and have been rebuilt since the release of the kernel and
> compiler updates will automatically use appropriate mitigation.  Out of
> kernel module builds which do not use kbuild require special flags.
> This is all covered in the kbase article.
>
> jeff
>