On Thu, Mar 27, 2014 at 11:38:41AM +0200, Michael S. Tsirkin wrote:
> When mergeable buffers are disabled, and the
> incoming packet is too large for the rx buffer,
> get_rx_bufs returns success.
>
> This was intentional in order for make recvmsg
> truncate the packet and then handle_rx would
> detect err != sock_len and drop it.
>
> Unfortunately we pass the original sock_len to
> recvmsg - which means we use parts of iov not fully
> validated.
>
> Fix this up by detecting this overrun and doing packet drop
> immediately.
>
> CVE-2014-0055
Ouch wrong CVE#. It's CVE-2014-0077 actually.
Will resend V2 with the corrected commit log now.
> Signed-off-by: Michael S. Tsirkin <m...@redhat.com>
> ---
>
> Note: this is needed for -stable.
>
> I wonder if this can still make the release.
>
> drivers/vhost/net.c | 14 ++++++++++++++
> 1 file changed, 14 insertions(+)
>
> diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
> index a0fa5de..026be58 100644
> --- a/drivers/vhost/net.c
> +++ b/drivers/vhost/net.c
> @@ -532,6 +532,12 @@ static int get_rx_bufs(struct vhost_virtqueue *vq,
> *iovcount = seg;
> if (unlikely(log))
> *log_num = nlogs;
> +
> + /* Detect overrun */
> + if (unlikely(datalen > 0)) {
> + r = UIO_MAXIOV + 1;
> + goto err;
> + }
> return headcount;
> err:
> vhost_discard_vq_desc(vq, headcount);
> @@ -587,6 +593,14 @@ static void handle_rx(struct vhost_net *net)
> /* On error, stop handling until the next kick. */
> if (unlikely(headcount < 0))
> break;
> + /* On overrun, truncate and discard */
> + if (unlikely(headcount > UIO_MAXIOV)) {
> + msg.msg_iovlen = 1;
> + err = sock->ops->recvmsg(NULL, sock, &msg,
> + 1, MSG_DONTWAIT | MSG_TRUNC);
> + pr_debug("Discarded rx packet: len %zd\n", sock_len);
> + continue;
> + }
> /* OK, now we need to know about added descriptors. */
> if (!headcount) {
> if (unlikely(vhost_enable_notify(&net->dev, vq))) {
> --
> MST
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