hw/virtio: Acquire RCU read lock in virtqueue_packed_drop_all()

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>
Message-Id: <20210906104318.1569967-3-philmd@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>

diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index 240759ff0b7b61c868e6cacf5ed455cabba943fd..dd0ab433b8776094249785b93aa8c1c6d2ba6b51 100644 (file)
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -1703,6 +1703,8 @@ 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;