On Thu, Mar 30, 2017 at 11:59:16AM -0700, Linus Torvalds wrote: > But regardless of that, I think you're being silly to even look at the > iovec code. That code simply *isn't* critical enough that one or two > extra instructions matter. > > Show me profiles to the contrary. I dare you. > > Those things shouldn't be using *anything* odd at all. They should be > using "copy_from_user()". Nothing else. That they very definitely should not. And not because of access_ok() or might_fault() - this is one place where zero-padding is absolutely wrong. So unless you are going to take it out of copy_from_user() and pray that random shit ioctls in random shit drivers check the return value properly, copy_from_user() is no-go here.
