Description
Colin Percival discovered an information disclosure in the "Hyper
Threading Technology" architecture in processors which are capable of
simultaneous multithreading (in particular Intel Pentium 4, Intel
Mobile Pentium 4, and Intel Xeon processors). This allows a malicious
thread to monitor the execution of another thread on the same CPU.
This could be exploited to steal cryptographic keys, passwords, or
other arbitrary data from unrelated processes. Since it is not
possible to provide a safe patch in a short time, HyperThreading has
been disabled in the updated kernel packages for now. You can manually
enable HyperThreading again by passing the kernel parameter "ht=on" at
boot. (CAN-2005-0109)