On 04/09/2014 11:01 AM, Jan Beulich wrote:
On 09.04.14 at 16:41, <andrew.coop...@citrix.com> wrote:
The latter load however can easy fault; The arguments for %ds in
XSA-42/ CVE-2013-0228 applies to %{e,f,g}s as well.
And it was only that latter operation that I pointed at.
We don't seem to reference %fs after the pop so doing the fixup (as
David suggested) should be enough?
-boris
Furthermore, I am a little concerned about the performance impact of
this. I would have thought that in most cases, %fs will already be
correct, at which point reloading it twice is a waste of time.
Why would you expect %fs on the IRET path to commonly point to the
kernel segment rather than whatever user mode wants/needs? Also, I'm
not sure adding conditionals here wouldn't harm performance about as
much as the save/load/restore. If anything I'd look into open coding
GET_THREAD_INFO() without using %fs for this single case.
Jan
_______________________________________________
Xen-devel mailing list
xen-de...@lists.xen.org
http://lists.xen.org/xen-devel
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
