Last year Nvidia told GPU owners worried about Rowhammer to switch on error correction. Four researchers at the University of Toronto have now shown that the same attack, aimed harder, goes straight through it. Their technique, GPUThor, is the first Rowhammer attack to defeat ECC on Nvidia GPUs. It works on four Ampere-generation workstation cards: the RTX A4000, A4500, A5000 and A6000. On each, it turns an ordinary unprivileged CUDA program into a root shell on the host computer, with error correction enabled. Chris S. Lin, Joyce Qu, Aditya Rajeev and Gururaj Saileshwar published the paper on 25 August. They…