Philipp Rumpf wrote:
>
> On Mon, Nov 27, 2000 at 10:36:34AM -0800, H. Peter Anvin wrote:
> > Followup to: <[EMAIL PROTECTED]>
> > By author: Philipp Rumpf <[EMAIL PROTECTED]>
> > In newsgroup: linux.dev.kernel
> > >
> > > I hope count isn't provided by userspace here ?
> > >
> > > > 1. What happens if the user space memory is swapped to disk? Will
> > > > verify_area() make sure that the memory is in physical RAM when it returns,
> > > > or will it return -EFAULT, or will something even worse happen?
> > >
> > > On i386, you'll sleep implicitly waiting for the page fault to be handled; in
> > > the generic case, anything could happen.
> > >
> >
> > That doesn't sound right. I would expect it to wait for the page to
> > be brought in on any and all architectures, otherwise it seems rather
> > impossible to write portable Linux kernel code.
>
> The code in question was
> memcpy_fromio(user_space_dst, iobase, count);
>
> Assuming user_space_dst is a userspace pointer, what I said is true; on some
> architectures we will be dereferencing random pointers in kernel space, and
> we won't get -EFAULT right on any architecture.
>
> Or did I miss something ?
>
Yes, the post you responded to was talking about verify_area() [which is,
admittedly, obsolete.]
-hpa
--
<[EMAIL PROTECTED]> at work, <[EMAIL PROTECTED]> in private!
"Unix gives you enough rope to shoot yourself in the foot."
http://www.zytor.com/~hpa/puzzle.txt
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [EMAIL PROTECTED]
Please read the FAQ at http://www.tux.org/lkml/
