On Thu, Jan 10, 2013 at 12:23:19PM +0200, Michael S. Tsirkin wrote: > On Thu, Jan 10, 2013 at 08:59:48AM +0100, Stefan Hajnoczi wrote: > > Multiqueue tun devices support detaching a tun_file from its tun_struct > > and re-attaching at a later point in time. This allows users to disable > > a specific queue temporarily. > > > > ioctl(TUNSETIFF) allows the user to specify the network interface to > > attach by name. This means the user can attempt to attach to interface > > "B" after detaching from interface "A". > > > > The driver is not designed to support this so check we are re-attaching > > to the right tun_struct. Failure to do so may lead to oops. > > > > Signed-off-by: Stefan Hajnoczi <stefa...@redhat.com> > > --- > > This fix is for 3.8-rc. > > > > drivers/net/tun.c | 2 ++ > > 1 file changed, 2 insertions(+) > > > > diff --git a/drivers/net/tun.c b/drivers/net/tun.c > > index fbd106e..cf6da6e 100644 > > --- a/drivers/net/tun.c > > +++ b/drivers/net/tun.c > > @@ -491,6 +491,8 @@ static int tun_attach(struct tun_struct *tun, struct > > file *file) > > err = -EINVAL; > > if (rcu_dereference_protected(tfile->tun, lockdep_rtnl_is_held())) > > goto out; > > + if (tfile->detached && tun != tfile->detached) > > + goto out; > > > > err = -EBUSY; > > if (!(tun->flags & TUN_TAP_MQ) && tun->numqueues == 1) > > -- > > 1.8.0.2 > > > I agree this is a bug but even with this patch, we still allow: > > SETIFF > SETQUEUE (DISABLED) > SETIFF > > Originally the rule always was that repeated setiff calls fail with > EINVAL. We broke that when we set tun to NULL. It's probably worth > preserving that, even if queue is disabled. Applying something like the below > instead will address this concern, won't it?
Sounds good. Stefan -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
