virtio: console: fix locking around send_sigio_to_port()

send_sigio_to_port() checks the value of guest_connected, which we
always modify under the inbuf_lock; make sure invocations of
send_sigio_to_port() have take the inbuf_lock around the call.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

1 files changed, 5 insertions, 3 deletions

diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
index 3572c5a92e8e..d5e2c7050291 100644
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -1661,7 +1661,9 @@ static void handle_control_message(struct ports_device *portdev,
                  * If the guest is connected, it'll be interested in
                  * knowing the host connection state changed.
                  */
+                spin_lock_irq(&port->inbuf_lock);
                 send_sigio_to_port(port);
+                spin_unlock_irq(&port->inbuf_lock);
                 break;
         case VIRTIO_CONSOLE_PORT_NAME:
                 /*
@@ -1781,13 +1783,13 @@ static void in_intr(struct virtqueue *vq)
         if (!port->guest_connected && !is_rproc_serial(port->portdev->vdev))
                 discard_port_data(port);
 
+        /* Send a SIGIO indicating new data in case the process asked for it */
+        send_sigio_to_port(port);
+
         spin_unlock_irqrestore(&port->inbuf_lock, flags);
 
         wake_up_interruptible(&port->waitqueue);
 
-        /* Send a SIGIO indicating new data in case the process asked for it */
-        send_sigio_to_port(port);
-
         if (is_console_port(port) && hvc_poll(port->cons.hvc))
                 hvc_kick();
 }