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> To clarify though, that requires an external attacker-controlled process to monitor the GPU, yes? Yes, they do it with high-speed probing of the amount alloc
by kangz 8y ago
> To clarify though, that requires an external attacker-controlled process to monitor the GPU, yes?
Yes, they do it with high-speed probing of the amount allocated GPU memory. This requires access to native APIs (specific OpenGL extensions in this case). Like you said there seems there would be simpler ways to achieve this, but the demonstration of this side-channel is still very interesting.
Varying the size of the textboxes might not help because the rendering engine of browsers can have a memory allocation per letter for example.
- monocasa 8y agoLast time I checked on Vulkan, you took a lot of GPU memory allocation into your own hands. You allocate large chunks that you then write your own allocator for to carve up (sort of like the distinction between sbrk/mmap and malloc). Is that still the case, and would that unintentionally avoid this side channel since the global GPU perf stats wouldn't necessarily see a difference on small allocations?
- DiabloD3 8y agoThat's not entirely true, and that's basically what all modern games do: switching buffers is an expensive context switch, so texture atlasses became the norm over a decade ago, as did stuffed vertex buffers.