Re: Hyper-Threading Vulnerability

andrea
2005-05-16T07:07:04Z

On Sun, May 15, 2005 at 03:38:22PM +0200, Mikulas Patocka wrote:
> Another possibility to get timing is from direct-io --- i.e. initiate
> direct io read, wait until one cache line contains new data and you can be
> sure that the next will contain new data in certain time. IDE controller
> bus master operation acts here as a timer.

There's no way to do direct-io through seccomp, all the fds are pipes
with twisted userland listening the other side of the pipe. So disabling
the tsc is more than enough to give to CPUShare users a peace of mind
with HT enabled and without having to flush the l2 cache either.
CPUShare is the only case I can imagine where an untrusted and random
bytecode running at 100% system load is the normal behaviour.