Re:Is Your VirtualBox Reading Your E-Mail? Reconstruction of...
by datenwolf on Sunday March 22, 2015 @02:18PM
(#9247691)
> should they be scrubbing vram as well
Yes, but VRAM is a tricky beast. Modern GPUs actually have MMUs and the VRAM address layout the CPU sees may not cover the whole of the memory of the graphics card.
> What happens if I watch 2 minutes of 1080p video - wouldn't we expect all previous framebuffer data to be flushed at that point ?
No, because the video frames will be queued in a circular buffer and anything outside of that doesn't get touched.
Re:Is Your VirtualBox Reading Your E-Mail? Reconstruction of...
by cesarb on Sunday March 22, 2015 @06:31PM
(#9248537)
The only way I can see to reliably scrub VRAM would be to use the GPU as a "dumb framebuffer" (without video acceleration), like in the good old days. Then to scrub what was used in the session it should be enough to draw a black screen, do a page flip, and draw a black screen again.
First, tails scrubs memory (or something like that) when you shut down - should they be scrubbing vram as well ?
Second, wouldn't it be quick and simple to "scrub" vram by filling it up with intensive usage after working on sensitive information ? What happens if I watch 2 minutes of 1080p video - wouldn't we expect all previous framebuffer data to be flushed at that point ?
Finally, I would be very curious to see how this changes as you work with multiple graphics cards in a multi-monitor setup. I tend to have all of my VMs in windows confined to a particular monitor that is driven by its own graphics card - presumably those guest operating systems are only accessing that framebuffer ?