Re: Hyper-Threading Vulnerability

Mikulas Patocka
2005-05-15T14:21:39Z

On Sun, 15 May 2005, Andi Kleen wrote:

> On Sun, May 15, 2005 at 03:51:05PM +0200, Mikulas Patocka wrote:
> >
> >
> > On Sun, 15 May 2005, Andi Kleen wrote:
> >
> > > On Fri, May 13, 2005 at 09:16:09PM +0200, Diego Calleja wrote:
> > > > El Fri, 13 May 2005 20:03:58 +0200,
> > > > Andi Kleen <ak@muc.de> escribi?:
> > > >
> > > >
> > > > > This is not a kernel problem, but a user space problem. The fix
> > > > > is to change the user space crypto code to need the same number of cache line
> > > > > accesses on all keys.
> > > >
> > > >
> > > > However they've patched the FreeBSD kernel to "workaround?" it:
> > > > ftp://ftp.freebsd.org/pub/FreeBSD/CERT/patches/SA-05:09/htt5.patch
> > >
> > > That's a similar stupid idea as they did with the disk write
> > > cache (lowering the MTBFs of their disks by considerable factors,
> > > which is much worse than the power off data loss problem)
> > > Let's not go down this path please.
> >
> > What wrong did they do with disk write cache?
>
> They turned it off by default, which according to disk vendors
> lowers the MTBF of your disk to a fraction of the original value.
>
> I bet the total amount of valuable data lost for FreeBSD users because
> of broken disks is much much bigger than what they gained from not losing
> in the rather hard to hit power off cases.
>
> -Andi

BTW. Is there any blacklist of disks with broken FLUSH CACHE command? Or a
list of companies that cheat in implementation of it?

Mikulas