1 files changed, 21 insertions, 6 deletions

diff --git a/drivers/net/usb/usbnet.c b/drivers/net/usb/usbnet.c
index 7b331e613e02..bf94e10a37c8 100644
--- a/drivers/net/usb/usbnet.c
+++ b/drivers/net/usb/usbnet.c
@@ -1241,7 +1241,9 @@ static int build_dma_sg(const struct sk_buff *skb, struct urb *urb)
         if (num_sgs == 1)
                 return 0;
 
-        urb->sg = kmalloc(num_sgs * sizeof(struct scatterlist), GFP_ATOMIC);
+        /* reserve one for zero packet */
+        urb->sg = kmalloc((num_sgs + 1) * sizeof(struct scatterlist),
+                          GFP_ATOMIC);
         if (!urb->sg)
                 return -ENOMEM;
 
@@ -1305,7 +1307,7 @@ netdev_tx_t usbnet_start_xmit (struct sk_buff *skb,
                 if (build_dma_sg(skb, urb) < 0)
                         goto drop;
         }
-        entry->length = length = urb->transfer_buffer_length;
+        length = urb->transfer_buffer_length;
 
         /* don't assume the hardware handles USB_ZERO_PACKET
          * NOTE:  strictly conforming cdc-ether devices should expect
@@ -1317,15 +1319,18 @@ netdev_tx_t usbnet_start_xmit (struct sk_buff *skb,
         if (length % dev->maxpacket == 0) {
                 if (!(info->flags & FLAG_SEND_ZLP)) {
                         if (!(info->flags & FLAG_MULTI_PACKET)) {
-                                urb->transfer_buffer_length++;
-                                if (skb_tailroom(skb)) {
+                                length++;
+                                if (skb_tailroom(skb) && !urb->num_sgs) {
                                         skb->data[skb->len] = 0;
                                         __skb_put(skb, 1);
-                                }
+                                } else if (urb->num_sgs)
+                                        sg_set_buf(&urb->sg[urb->num_sgs++],
+                                                        dev->padding_pkt, 1);
                         }
                 } else
                         urb->transfer_flags |= URB_ZERO_PACKET;
         }
+        entry->length = urb->transfer_buffer_length = length;
 
         spin_lock_irqsave(&dev->txq.lock, flags);
         retval = usb_autopm_get_interface_async(dev->intf);
@@ -1509,6 +1514,7 @@ void usbnet_disconnect (struct usb_interface *intf)
 
         usb_kill_urb(dev->interrupt);
         usb_free_urb(dev->interrupt);
+        kfree(dev->padding_pkt);
 
         free_netdev(net);
 }
@@ -1679,9 +1685,16 @@ usbnet_probe (struct usb_interface *udev, const struct usb_device_id *prod)
         /* initialize max rx_qlen and tx_qlen */
         usbnet_update_max_qlen(dev);
 
+        if (dev->can_dma_sg && !(info->flags & FLAG_SEND_ZLP) &&
+                !(info->flags & FLAG_MULTI_PACKET)) {
+                dev->padding_pkt = kzalloc(1, GFP_KERNEL);
+                if (!dev->padding_pkt)
+                        goto out4;
+        }
+
         status = register_netdev (net);
         if (status)
-                goto out4;
+                goto out5;
         netif_info(dev, probe, dev->net,
                    "register '%s' at usb-%s-%s, %s, %pM\n",
                    udev->dev.driver->name,
@@ -1699,6 +1712,8 @@ usbnet_probe (struct usb_interface *udev, const struct usb_device_id *prod)
 
         return 0;
 
+out5:
+        kfree(dev->padding_pkt);
 out4:
         usb_free_urb(dev->interrupt);
 out3: