[PATCH v3 2/3] hw/virtio: Acquire RCU read lock in virtqueue_packed_drop_all()

["Philippe Mathieu-Daudé" <philmd@redhat.com>]

vring_get_region_caches() must be called with the RCU read lock
acquired. virtqueue_packed_drop_all() does not, and uses the
'caches' pointer. Fix that by using the RCU_READ_LOCK_GUARD()
macro.

Reported-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
---
 hw/virtio/virtio.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index 97f60017466..7d3bf9091ee 100644
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -1704,6 +1704,8 @@ static unsigned int virtqueue_packed_drop_all(VirtQueue *vq)
     VirtIODevice *vdev = vq->vdev;
     VRingPackedDesc desc;
 
+    RCU_READ_LOCK_GUARD();
+
     caches = vring_get_region_caches(vq);
     if (!caches) {
         return 0;
-- 
2.31.1