[059/150] vhost/net: fix heads usage of ubuf_info

Submitted by Luis Henriques on March 26, 2013, 3:19 p.m.


Message ID 1364311249-14454-60-git-send-email-luis.henriques@canonical.com
State New
Headers show

Commit Message

Luis Henriques March 26, 2013, 3:19 p.m. -stable review patch.  If anyone has any objections, please let me know.


From: "Michael S. Tsirkin" <mst@redhat.com>

commit 46aa92d1ba162b4b3d6b7102440e459d4e4ee255 upstream.

ubuf info allocator uses guest controlled head as an index,
so a malicious guest could put the same head entry in the ring twice,
and we will get two callbacks on the same value.
To fix use upend_idx which is guaranteed to be unique.

Reported-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
 drivers/vhost/net.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

Patch hide | download patch | download mbox

diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index 3c4dcc3d9..f2e8236 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -235,7 +235,8 @@  static void handle_tx(struct vhost_net *net)
 				msg.msg_controllen = 0;
 				ubufs = NULL;
 			} else {
-				struct ubuf_info *ubuf = &vq->ubuf_info[head];
+				struct ubuf_info *ubuf;
+				ubuf = vq->ubuf_info + vq->upend_idx;
 				vq->heads[vq->upend_idx].len = len;
 				ubuf->callback = vhost_zerocopy_callback;