vhost: Fix element in vhost_svq_add failure

Coverity rightly reports that is not free in that case.

Fixes: Coverity CID 1487559
Fixes: 100890f7ca ("vhost: Shadow virtqueue buffers forwarding")

Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Message-Id: <20220512175747.142058-7-eperezma@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

1 files changed, 8 insertions, 0 deletions

diff --git a/hw/virtio/vhost-shadow-virtqueue.c b/hw/virtio/vhost-shadow-virtqueue.c
index a8376ef82b..56c96ebd13 100644
--- a/hw/virtio/vhost-shadow-virtqueue.c
+++ b/hw/virtio/vhost-shadow-virtqueue.c
@@ -199,11 +199,19 @@ static bool vhost_svq_add_split(VhostShadowVirtqueue *svq,
     return true;
 }
 
+/**
+ * Add an element to a SVQ.
+ *
+ * The caller must check that there is enough slots for the new element. It
+ * takes ownership of the element: In case of failure, it is free and the SVQ
+ * is considered broken.
+ */
 static bool vhost_svq_add(VhostShadowVirtqueue *svq, VirtQueueElement *elem)
 {
     unsigned qemu_head;
     bool ok = vhost_svq_add_split(svq, elem, &qemu_head);
     if (unlikely(!ok)) {
+        g_free(elem);
         return false;
     }