any details on which CPUs that worked on? /cc @lavados @yuvalyarom @anders_fogh @misc0110
On stage today, during the Cyber-ITL talk at ShmooCon, Patrick dropped a little 0day that speculative execution executed data (ignoring non-execute markings). That’s r-x... for those keeping track. (rowhammer for the write anyone?)
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also: "r-x"? don't you mean "rw-"?
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I think he meant that we have a way to do read and execute with those techniques as in r-x. rwx with rowhammer.
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Not too surprising: if the name of the game is speed you throw out all security checks, for privilege level as well as executable bit. I can't think of any other security checks right now but if there are any, they're also likely bypassed in speculative execution.
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On that note, I'm beginning to wonder if one could use speculative execution to make a CPU *actually* divide by zero. Side channel being a sudden creation of a local black hole.
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Ohhh, I'd forgotten about that one... :D
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Pretty sure data can't be written out of the store buffer to memory until an instruction retires. Memory is global, so it would be visible to other threads (and not be speculative) if that occured.
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Should systems allow dynamically-generated code & if so, what’s right mode for data/stack areas where instructions written?
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if you haven't seen it, this seems like something too, lots of notes that need to be organised.
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Do you know if that talk was recorded and will be posted somewhere? I would like to see it despite missing Shmoocon this year.
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I'm failing to see how this is any worse than Spectre already is. At best it seems to give you more Spectre gadgets to work with.
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I suppose this would allow for an end run around OpenBSD's W^X... *sigh*
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Why is it called ShmooCon?
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Aww, man.
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anything more on this?
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Great.
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