That is a line that historically had no one in it. There was much wringing of hands over WebGL, but "access to raw GPU memory" never came up as a concern, and i

That is a line that historically had no one in it. There was much wringing of hands over WebGL, but "access to raw GPU memory" never came up as a concern, and is not even the issue here! This exploit specifically only functions on UMA devices, where GPUs use unified system memory, and thus have no more or less access to it than ArrayBuffers. It turns out CPU memory accesses are too slow (really simplifying here) to rowhammer.