Re: [PATCH v3 2/2] vhost: improve error handling in desc_to_mbuf

[Maxime Coquelin]

On 8/2/22 02:49, Claudio Fontana wrote:

check when increasing vec_idx that it is still valid
in the (buf_len < dev->vhost_hlen) case too.

Tested-by: Claudio Fontana <cfont...@suse.de>
Signed-off-by: Claudio Fontana <cfont...@suse.de>
---
  lib/vhost/virtio_net.c | 5 ++++-
  1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/lib/vhost/virtio_net.c b/lib/vhost/virtio_net.c
index eb19e54c2b..20ed951979 100644
--- a/lib/vhost/virtio_net.c
+++ b/lib/vhost/virtio_net.c
@@ -2704,12 +2704,15 @@ desc_to_mbuf(struct virtio_net *dev, struct 
vhost_virtqueue *vq,
        if (unlikely(buf_len < dev->vhost_hlen)) {
                buf_offset = dev->vhost_hlen - buf_len;
                vec_idx++;
+               if (unlikely(vec_idx >= nr_vec))
+                       goto error;
                buf_addr = buf_vec[vec_idx].buf_addr;
                buf_iova = buf_vec[vec_idx].buf_iova;
                buf_len = buf_vec[vec_idx].buf_len;
                buf_avail  = buf_len - buf_offset;
        } else if (buf_len == dev->vhost_hlen) {
-               if (unlikely(++vec_idx >= nr_vec))
+               vec_idx++;
+               if (unlikely(vec_idx >= nr_vec))
                        goto error;
                buf_addr = buf_vec[vec_idx].buf_addr;
                buf_iova = buf_vec[vec_idx].buf_iova;

This patch is no more required since fixes for CVE-2022-2132 takes care
of this:
dc1516e260a0 ("vhost: fix header spanned across more than two descriptors")
71bd0cc536ad ("vhost: discard too small descriptor chains")

Maxime