Bugzilla: 1081503
Upstream-status: Sent to netdev

From patchwork Thu Mar 27 10:53:37 2014
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Subject: [net] vhost: validate vhost_get_vq_desc return value
From: "Michael S. Tsirkin" <mst@redhat.com>
X-Patchwork-Id: 334291
Message-Id: <1395917517-30937-1-git-send-email-mst@redhat.com>
To: linux-kernel@vger.kernel.org
Cc: kvm@vger.kernel.org, virtio-dev@lists.oasis-open.org,
 virtualization@lists.linux-foundation.org, netdev@vger.kernel.org,
 David Miller <davem@davemloft.net>, Jason Wang <jasowang@redhat.com>
Date: Thu, 27 Mar 2014 12:53:37 +0200

vhost fails to validate negative error code
from vhost_get_vq_desc causing
a crash: we are using -EFAULT which is 0xfffffff2
as vector size, which exceeds the allocated size.

The code in question was introduced in commit
8dd014adfea6f173c1ef6378f7e5e7924866c923
    vhost-net: mergeable buffers support

CVE-2014-0055

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

---
This is needed in -stable.

 drivers/vhost/net.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index 026be58..e1e22e0 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -505,9 +505,13 @@ static int get_rx_bufs(struct vhost_virtqueue *vq,
 			r = -ENOBUFS;
 			goto err;
 		}
-		d = vhost_get_vq_desc(vq->dev, vq, vq->iov + seg,
+		r = vhost_get_vq_desc(vq->dev, vq, vq->iov + seg,
 				      ARRAY_SIZE(vq->iov) - seg, &out,
 				      &in, log, log_num);
+		if (unlikely(r < 0))
+			goto err;
+
+		d = r;
 		if (d == vq->num) {
 			r = 0;
 			goto err;