sunvnet: free pending tx buffers before clearing ring data

This patch moves the clearing of ring data in vnet_port_free_tx_bufs to after
 the freeing of pending buffers in the ring. Otherwise, this can result in
 dereferencing a NULL pointer.

Reported-by: Sowmini Varadhan <sowmini.varadhan@oracle.com>
Signed-off-by: David L Stevens <david.stevens@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 11 insertions, 10 deletions

diff --git a/drivers/net/ethernet/sun/sunvnet.c b/drivers/net/ethernet/sun/sunvnet.c
index b5a1d3d7b0bf..fe044f31708e 100644
--- a/drivers/net/ethernet/sun/sunvnet.c
+++ b/drivers/net/ethernet/sun/sunvnet.c
@@ -1637,16 +1637,9 @@ static void vnet_port_free_tx_bufs(struct vnet_port *port)
         int i;
 
         dr = &port->vio.drings[VIO_DRIVER_TX_RING];
-        if (dr->base) {
-                ldc_free_exp_dring(port->vio.lp, dr->base,
-                                   (dr->entry_size * dr->num_entries),
-                                   dr->cookies, dr->ncookies);
-                dr->base = NULL;
-                dr->entry_size = 0;
-                dr->num_entries = 0;
-                dr->pending = 0;
-                dr->ncookies = 0;
-        }
+
+        if (dr->base == NULL)
+                return;
 
         for (i = 0; i < VNET_TX_RING_SIZE; i++) {
                 struct vio_net_desc *d;
@@ -1666,6 +1659,14 @@ static void vnet_port_free_tx_bufs(struct vnet_port *port)
                 port->tx_bufs[i].skb = NULL;
                 d->hdr.state = VIO_DESC_FREE;
         }
+        ldc_free_exp_dring(port->vio.lp, dr->base,
+                           (dr->entry_size * dr->num_entries),
+                           dr->cookies, dr->ncookies);
+        dr->base = NULL;
+        dr->entry_size = 0;
+        dr->num_entries = 0;
+        dr->pending = 0;
+        dr->ncookies = 0;
 }
 
 static int vnet_port_alloc_tx_ring(struct vnet_port *port)