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SubjectRe: goldfish driver: Missing get_user_pages in goldfish_pipe_read_write()
* Greg Kroah-Hartman (gregkh@linuxfoundation.org) wrote:
> On Thu, Jun 27, 2013 at 01:35:32PM -0400, Mathieu Desnoyers wrote:
> > The following code snippet:
> >
> > drivers/platform/goldfish/goldfish_pipe.c:
> > goldfish_pipe_read_write()
> >
> > /* Ensure that the corresponding page is properly mapped */
> > /* FIXME: this isn't safe or sufficient - use get_user_pages */
> > if (is_write) {
> > char c;
> > /* Ensure that the page is mapped and readable */
> > if (__get_user(c, (char __user *)address)) {
> > if (!ret)
> > ret = -EFAULT;
> > break;
> > }
> > } else {
> > /* Ensure that the page is mapped and writable */
> > if (__put_user(0, (char __user *)address)) {
> > if (!ret)
> > ret = -EFAULT;
> > break;
> > }
> > }
> >
> > Seems to lack the kind of validation required to make it fail properly
> > if the memory range is not fully populated.
>
> This is an emulated platform only, so it's probably not a big deal,
> right?

You're probably right. As long as it is not configured and somehow still
accessible on a production device.

>
> > I see that this feature has been merged in Linux kernel 3.9, but the
> > FIXME is still there in 3.10-rc7. Any plans on fixing this ?
>
> It would be good to get fixed, but probably way down on the priority
> list.

Agreed,

Thanks,

Mathieu

>
> thanks,
>
> greg k-h

--
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com


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