Amit Shah <amit.shah@xxxxxxxxxx> writes: > There's a window between find_port_by_devt() returning a port and us > taking a kref on the port, where the port could get unplugged. Fix it > by taking the reference in find_port_by_devt() itself. > > Problem reported and analyzed by Mateusz Guzik. This fix is clearly correct, but what about the other find_port_by_* functions? Applied, Rusty. > > CC: <stable@xxxxxxxxxxxxxxx> > Reported-by: Mateusz Guzik <mguzik@xxxxxxxxxx> > Signed-off-by: Amit Shah <amit.shah@xxxxxxxxxx> > --- > drivers/char/virtio_console.c | 13 ++++++------- > 1 file changed, 6 insertions(+), 7 deletions(-) > > diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c > index 1b456fe..291f437 100644 > --- a/drivers/char/virtio_console.c > +++ b/drivers/char/virtio_console.c > @@ -272,9 +272,12 @@ static struct port *find_port_by_devt_in_portdev(struct ports_device *portdev, > unsigned long flags; > > spin_lock_irqsave(&portdev->ports_lock, flags); > - list_for_each_entry(port, &portdev->ports, list) > - if (port->cdev->dev == dev) > + list_for_each_entry(port, &portdev->ports, list) { > + if (port->cdev->dev == dev) { > + kref_get(&port->kref); > goto out; > + } > + } > port = NULL; > out: > spin_unlock_irqrestore(&portdev->ports_lock, flags); > @@ -1019,14 +1022,10 @@ static int port_fops_open(struct inode *inode, struct file *filp) > struct port *port; > int ret; > > + /* We get the port with a kref here */ > port = find_port_by_devt(cdev->dev); > filp->private_data = port; > > - /* Prevent against a port getting hot-unplugged at the same time */ > - spin_lock_irq(&port->portdev->ports_lock); > - kref_get(&port->kref); > - spin_unlock_irq(&port->portdev->ports_lock); > - > /* > * Don't allow opening of console port devices -- that's done > * via /dev/hvc > -- > 1.8.1.4 -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html