Messages in this thread | | | Date | Tue, 17 Jun 2008 23:30:44 +0200 | From | Andi Kleen <> | Subject | Re: BUG: mmapfile/writev spurious zero bytes (x86_64/not i386, bisected, reproducable) |
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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 copy_from_user)
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?
-Andi
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