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Commit d8316f39 authored by Michael S. Tsirkin's avatar Michael S. Tsirkin Committed by David S. Miller
Browse files

vhost: fix total length when packets are too short 



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-2014-0077

Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 05efa8c9

drivers/vhost/net.c

+14 −0
Original line number Original line Diff line number Diff line
@@ -532,6 +532,12 @@ static int get_rx_bufs(struct vhost_virtqueue *vq, 
	*iovcount = seg;

	*iovcount = seg;

	if (unlikely(log))

	if (unlikely(log))

		*log_num = nlogs;

		*log_num = nlogs;



	/* Detect overrun */

	if (unlikely(datalen > 0)) {

		r = UIO_MAXIOV + 1;

		goto err;

	}

	return headcount;

	return headcount;

err:

err:

	vhost_discard_vq_desc(vq, headcount);

	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. */

		/* On error, stop handling until the next kick. */

		if (unlikely(headcount < 0))

		if (unlikely(headcount < 0))

			break;

			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. */

		/* OK, now we need to know about added descriptors. */

		if (!headcount) {

		if (!headcount) {

			if (unlikely(vhost_enable_notify(&net->dev, vq))) {

			if (unlikely(vhost_enable_notify(&net->dev, vq))) {