From 600f5ce356b44d8fa5a611ff6b034eb95ecf04e7 Mon Sep 17 00:00:00 2001 From: Stefan Hajnoczi Date: Wed, 16 Nov 2016 20:17:32 +0000 Subject: [PATCH] virtio-crypto: fix virtio_queue_set_notification() race We must check for new virtqueue buffers after re-enabling notifications. This prevents the race condition where the guest added buffers just after we stopped popping the virtqueue but before we re-enabled notifications. I think the virtio-crypto code was based on virtio-net but this crucial detail was missed. virtio-net does not have the race condition because it processes the virtqueue one more time after re-enabling notifications. Cc: Gonglei Signed-off-by: Stefan Hajnoczi Tested-by: Alexey Kardashevskiy Reviewed-by: Michael S. Tsirkin Signed-off-by: Michael S. Tsirkin Reviewed-by: Gonglei --- hw/virtio/virtio-crypto.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) diff --git a/hw/virtio/virtio-crypto.c b/hw/virtio/virtio-crypto.c index 32938433b7..847dc9dafd 100644 --- a/hw/virtio/virtio-crypto.c +++ b/hw/virtio/virtio-crypto.c @@ -692,8 +692,17 @@ static void virtio_crypto_dataq_bh(void *opaque) return; } - virtio_crypto_handle_dataq(vdev, q->dataq); - virtio_queue_set_notification(q->dataq, 1); + for (;;) { + virtio_crypto_handle_dataq(vdev, q->dataq); + virtio_queue_set_notification(q->dataq, 1); + + /* Are we done or did the guest add more buffers? */ + if (virtio_queue_empty(q->dataq)) { + break; + } + + virtio_queue_set_notification(q->dataq, 0); + } } static void -- GitLab