[Info-vax] Intel junk...Kernel-memory-leaking Intel processor design flaw forces Linux, Windows redesign

[Andy Burns]

Tim Streater wrote:

> Does that involve instructions that operate on the cache. Such as
> "clear cache"?

Yes, for the example I saw

<https://gist.github.com/ErikAugust/724d4a969fb2c6ae1bbd7b2a9e3d4bb6/revisions>

but I think it was only using spectre techniques to read from a chunk of 
memory within the same process, to demonstrate how the timing works.

The x86-64 reference manual

<https://www.intel.com/content/dam/www/public/us/en/documents/manuals/64-ia-32-architectures-software-developer-instruction-set-reference-manual-325383.pdf>

states

"The CLFLUSH instruction can be used at all privilege levels and is 
subject to all permission checking and faults associated with a byte load"

so perhaps the example is too simplistic and a real attack wouldn't be 
able to flush the target area of memory from the cache lines, unless it 
already had permission to access that memory?