Measured in install base on desktop/laptop, Intel is much more popular than NVIDIA.
Shader compiler bugs are pretty serious, but they should have exploit mitigation. It takes GLSL or SPIR-V as input and emits GPU machine code blobs, the compiler doesn't need any special privileges. It's just a big attack surface.
That still gives the attacker the ability to emit arbitrary GPU machine code.
I am not familiar with the details of GPUs, but it would not suprise me if arbitrary code execution on a GPU can lead to root access on the main CPU. Anyone know if there is any protections against this (or if it is architectually impossible)?
GPU shaders are, by design, arbitrary GPU code execution. You don't have to do anything special or create an attack per-se. Shaders can't lead to execution of CPU code on their own, they are blackboxed and only have access to (limited) GPU memory.
I can imagine the potential for a combined CPU-GPU exploit, but it's not likely to hinge on a shader. I wouldn't say absolutely "impossible" but if I was looking for GPU exploits, I'd poke at the compiler and API first.
Shader compiler bugs are pretty serious, but they should have exploit mitigation. It takes GLSL or SPIR-V as input and emits GPU machine code blobs, the compiler doesn't need any special privileges. It's just a big attack surface.