vhost: validate vhost_get_vq_desc return value

vhost fails to validate negative error code
from vhost_get_vq_desc causing
a crash: we are using -EFAULT which is 0xfffffff2
as vector size, which exceeds the allocated size.

The code in question was introduced in commit
8dd014adfea6f173c1ef6378f7e5e7924866c923
    vhost-net: mergeable buffers support

CVE-2014-0055

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index 026be58..e1e22e0 100644 (file)
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -505,9 +505,13 @@ static int get_rx_bufs(struct vhost_virtqueue *vq,
                        r = -ENOBUFS;
                        goto err;
                }
-               d = vhost_get_vq_desc(vq->dev, vq, vq->iov + seg,
+               r = vhost_get_vq_desc(vq->dev, vq, vq->iov + seg,
                                      ARRAY_SIZE(vq->iov) - seg, &out,
                                      &in, log, log_num);
+               if (unlikely(r < 0))
+                       goto err;
+
+               d = r;
                if (d == vq->num) {
                        r = 0;
                        goto err;