net: Fix wrong interpretation of some copy_to_user() results.

net: Fix wrong interpretation of some copy_to_user() results.

[ Upstream commit: 653252c2302cdf2dfbca66a7e177f7db783f9efa ]

I found some places, that erroneously return the value obtained from
the copy_to_user() call: if some amount of bytes were not able to get
to the user (this is what this one returns) the proper behavior is to
return the -EFAULT error, not that number itself.

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>