diff options
| author | Paul Durrant <pdurrant@amazon.com> | 2019-12-13 13:20:40 +0000 |
|---|---|---|
| committer | Jakub Kicinski <jakub.kicinski@netronome.com> | 2019-12-15 11:40:15 -0800 |
| commit | fd42bfd1bb31f9a521be6b4f1bd89b85abc08d20 (patch) | |
| tree | 9bdcee15484dd3a8c51acf9a7e52c24335eb82b4 | |
| parent | 858ce8ca62ea1530f2779d0e3f934b0176e663c3 (diff) | |
| download | linux-fd42bfd1bb31f9a521be6b4f1bd89b85abc08d20.tar.bz2 | |
xen-netback: avoid race that can lead to NULL pointer dereference
In function xenvif_disconnect_queue(), the value of queue->rx_irq is
zeroed *before* queue->task is stopped. Unfortunately that task may call
notify_remote_via_irq(queue->rx_irq) and calling that function with a
zero value results in a NULL pointer dereference in evtchn_from_irq().
This patch simply re-orders things, stopping all tasks before zero-ing the
irq values, thereby avoiding the possibility of the race.
Fixes: 2ac061ce97f4 ("xen/netback: cleanup init and deinit code")
Signed-off-by: Paul Durrant <pdurrant@amazon.com>
Acked-by: Wei Liu <wei.liu@kernel.org>
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
| -rw-r--r-- | drivers/net/xen-netback/interface.c | 24 |
1 files changed, 12 insertions, 12 deletions
diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c index 68dd7bb07ca6..f15ba3de6195 100644 --- a/drivers/net/xen-netback/interface.c +++ b/drivers/net/xen-netback/interface.c @@ -628,18 +628,6 @@ err: static void xenvif_disconnect_queue(struct xenvif_queue *queue) { - if (queue->tx_irq) { - unbind_from_irqhandler(queue->tx_irq, queue); - if (queue->tx_irq == queue->rx_irq) - queue->rx_irq = 0; - queue->tx_irq = 0; - } - - if (queue->rx_irq) { - unbind_from_irqhandler(queue->rx_irq, queue); - queue->rx_irq = 0; - } - if (queue->task) { kthread_stop(queue->task); queue->task = NULL; @@ -655,6 +643,18 @@ static void xenvif_disconnect_queue(struct xenvif_queue *queue) queue->napi.poll = NULL; } + if (queue->tx_irq) { + unbind_from_irqhandler(queue->tx_irq, queue); + if (queue->tx_irq == queue->rx_irq) + queue->rx_irq = 0; + queue->tx_irq = 0; + } + + if (queue->rx_irq) { + unbind_from_irqhandler(queue->rx_irq, queue); + queue->rx_irq = 0; + } + xenvif_unmap_frontend_data_rings(queue); } |