[PATCH 4.4 17/20] xen-netfront: Delete rx_refill_timer in xennet_disconnect_backend()

From: Greg Kroah-Hartman
Date: Mon Feb 13 2017 - 08:10:29 EST


4.4-stable review patch. If anyone has any objections, please let me know.

------------------

From: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>

commit 74470954857c264168d2b5a113904cf0cfd27d18 upstream.

rx_refill_timer should be deleted as soon as we disconnect from the
backend since otherwise it is possible for the timer to go off before
we get to xennet_destroy_queues(). If this happens we may dereference
queue->rx.sring which is set to NULL in xennet_disconnect_backend().

Signed-off-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
Reviewed-by: Juergen Gross <jgross@xxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
drivers/net/xen-netfront.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/net/xen-netfront.c
+++ b/drivers/net/xen-netfront.c
@@ -1391,6 +1391,8 @@ static void xennet_disconnect_backend(st
for (i = 0; i < num_queues && info->queues; ++i) {
struct netfront_queue *queue = &info->queues[i];

+ del_timer_sync(&queue->rx_refill_timer);
+
if (queue->tx_irq && (queue->tx_irq == queue->rx_irq))
unbind_from_irqhandler(queue->tx_irq, queue);
if (queue->tx_irq && (queue->tx_irq != queue->rx_irq)) {
@@ -1745,7 +1747,6 @@ static void xennet_destroy_queues(struct

if (netif_running(info->netdev))
napi_disable(&queue->napi);
- del_timer_sync(&queue->rx_refill_timer);
netif_napi_del(&queue->napi);
}