Re: [PATCH net] vhost: fix total length when packets are too short
From: "Michael S. Tsirkin" <mst@redhat.com>
Date: 2014-03-27 09:58:38
Also in:
kvm, lkml, virtualization
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.
quoted hunk ↗ jump to hunk
Signed-off-by: Michael S. Tsirkin <mst@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