| Message ID | 1395912759-30435-1-git-send-email-mst@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
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 <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 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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))) {
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 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(+)