[Qemu-devel] [2.2 PATCH] virtio-net: fix unmap leak

[Jason Wang <jasowang@redhat.com>]

virtio_net_handle_ctrl() and other functions that process control vq
request call iov_discard_front() which will shorten the iov. This will
lead unmapping in virtqueue_push() leaks mapping.

Fixes this by keeping the original iov untouched and using a temp variable
in those functions.

Cc: Wen Congyang <wency@cn.fujitsu.com>
Cc: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Cc: qemu-stable@nongnu.org
Signed-off-by: Jason Wang <jasowang@redhat.com>
---
 hw/net/virtio-net.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
index 9b88775..fdb4edd 100644
--- a/hw/net/virtio-net.c
+++ b/hw/net/virtio-net.c
@@ -798,7 +798,7 @@ static void virtio_net_handle_ctrl(VirtIODevice *vdev, VirtQueue *vq)
     virtio_net_ctrl_ack status = VIRTIO_NET_ERR;
     VirtQueueElement elem;
     size_t s;
-    struct iovec *iov;
+    struct iovec *iov, *iov2;
     unsigned int iov_cnt;
 
     while (virtqueue_pop(vq, &elem)) {
@@ -808,8 +808,12 @@ static void virtio_net_handle_ctrl(VirtIODevice *vdev, VirtQueue *vq)
             exit(1);
         }
 
-        iov = elem.out_sg;
         iov_cnt = elem.out_num;
+        s = sizeof(struct iovec) * elem.out_num;
+        iov = g_malloc(s);
+        memcpy(iov, elem.out_sg, s);
+        iov2 = iov;
+
         s = iov_to_buf(iov, iov_cnt, 0, &ctrl, sizeof(ctrl));
         iov_discard_front(&iov, &iov_cnt, sizeof(ctrl));
         if (s != sizeof(ctrl)) {
@@ -833,6 +837,7 @@ static void virtio_net_handle_ctrl(VirtIODevice *vdev, VirtQueue *vq)
 
         virtqueue_push(vq, &elem, sizeof(status));
         virtio_notify(vdev, vq);
+        g_free(iov2);
     }
 }
 
-- 
1.9.1