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Bugzilla: 1081504
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Upstream-status: Sent to netdev list
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From patchwork Thu Mar 27 10:00:26 2014
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Content-Type: text/plain; charset="utf-8"
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MIME-Version: 1.0
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Content-Transfer-Encoding: 7bit
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Subject: [PATCHv2,net] vhost: fix total length when packets are too short
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From: "Michael S. Tsirkin" <mst@redhat.com>
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X-Patchwork-Id: 334283
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Message-Id: <20140327100026.GA30715@redhat.com>
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To: linux-kernel@vger.kernel.org
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Cc: kvm@vger.kernel.org, virtio-dev@lists.oasis-open.org,
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virtualization@lists.linux-foundation.org, netdev@vger.kernel.org,
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Jason Wang <jasowang@redhat.com>, David Miller <davem@davemloft.net>
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Date: Thu, 27 Mar 2014 12:00:26 +0200
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When mergeable buffers are disabled, and the
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incoming packet is too large for the rx buffer,
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get_rx_bufs returns success.
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This was intentional in order for make recvmsg
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truncate the packet and then handle_rx would
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detect err != sock_len and drop it.
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Unfortunately we pass the original sock_len to
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recvmsg - which means we use parts of iov not fully
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validated.
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Fix this up by detecting this overrun and doing packet drop
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immediately.
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CVE-2014-0077
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Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
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---
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Changes from v1:
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Fix CVE# in the commit log.
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Patch is unchanged.
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Note: this is needed for -stable.
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I wonder if this can still make the release.
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drivers/vhost/net.c | 14 ++++++++++++++
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1 file changed, 14 insertions(+)
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diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
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index a0fa5de..026be58 100644
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--- a/drivers/vhost/net.c
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+++ b/drivers/vhost/net.c
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@@ -532,6 +532,12 @@ static int get_rx_bufs(struct vhost_virtqueue *vq,
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*iovcount = seg;
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if (unlikely(log))
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*log_num = nlogs;
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+
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+ /* Detect overrun */
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+ if (unlikely(datalen > 0)) {
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+ r = UIO_MAXIOV + 1;
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+ goto err;
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+ }
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return headcount;
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err:
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vhost_discard_vq_desc(vq, headcount);
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@@ -587,6 +593,14 @@ static void handle_rx(struct vhost_net *net)
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/* On error, stop handling until the next kick. */
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if (unlikely(headcount < 0))
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break;
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+ /* On overrun, truncate and discard */
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+ if (unlikely(headcount > UIO_MAXIOV)) {
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+ msg.msg_iovlen = 1;
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+ err = sock->ops->recvmsg(NULL, sock, &msg,
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+ 1, MSG_DONTWAIT | MSG_TRUNC);
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+ pr_debug("Discarded rx packet: len %zd\n", sock_len);
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+ continue;
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+ }
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/* OK, now we need to know about added descriptors. */
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if (!headcount) {
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if (unlikely(vhost_enable_notify(&net->dev, vq))) {
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