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    SubjectRe: BUG: mmapfile/writev spurious zero bytes (x86_64/not i386, bisected, reproducable)
    Linus Torvalds wrote:
    > On Tue, 17 Jun 2008, Andi Kleen wrote:
    >> If that fixes anything:
    >> - The caller is broken because it shouldn't pass a faulting source to copy_to_user()
    >> - And you broken copy_from_user error reporting which shares the same code
    > Andi, I'm sorry I cc'd you. You are the author of that crap, but the bug
    > seems to be that you never even understood what copy_from_user() is
    > supposed to do.
    > The whole *and*only* reason for copy_to/from_user() existing AT ALL is
    > exactly the fact that the source or destination access can fault.

    yes, but only one of them (destination for copy_to_user and source for

    Or are you're describing copy_in_user()?

    > I don't really see why you continually start arguing about things that are
    > OBVIOUSLY BUGGY, as if they weren't buggy. Once somebody has debugged a
    > buggy routine, you shouldn't argue against it.
    > So here's a hint: next time I claim some code of yours is buggy, either
    > just acknowledge the bug, or stay silent. You'll look smarter that way.

    Ok if I'm really wrong on this (but frankly I don't see the mistake, sorry)
    for my person edification: what's a legitimate case for copy_to_user()
    where the source can fault?


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      Last update: 2008-06-17 23:33    [W:0.020 / U:46.476 seconds]
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