1 files changed, 24 insertions, 4 deletions

diff --git a/drivers/net/wireless/rt2x00/rt2x00usb.c b/drivers/net/wireless/rt2x00/rt2x00usb.c
index 1f5675dd329f..568d73847dca 100644
--- a/drivers/net/wireless/rt2x00/rt2x00usb.c
+++ b/drivers/net/wireless/rt2x00/rt2x00usb.c
@@ -221,7 +221,9 @@ static void rt2x00usb_interrupt_rxdone(struct urb *urb)
         struct data_ring *ring = entry->ring;
         struct rt2x00_dev *rt2x00dev = ring->rt2x00dev;
         struct sk_buff *skb;
+        struct ieee80211_hdr *hdr;
         struct rxdata_entry_desc desc;
+        int header_size;
         int frame_size;
 
         if (!test_bit(DEVICE_ENABLED_RADIO, &rt2x00dev->flags) ||
@@ -243,19 +245,37 @@ static void rt2x00usb_interrupt_rxdone(struct urb *urb)
          * Allocate a new sk buffer to replace the current one.
          * If allocation fails, we should drop the current frame
          * so we can recycle the existing sk buffer for the new frame.
+         * As alignment we use 2 and not NET_IP_ALIGN because we need
+         * to be sure we have 2 bytes room in the head. (NET_IP_ALIGN
+         * can be 0 on some hardware). We use these 2 bytes for frame
+         * alignment later, we assume that the chance that
+         * header_size % 4 == 2 is bigger then header_size % 2 == 0
+         * and thus optimize alignment by reserving the 2 bytes in
+         * advance.
          */
         frame_size = entry->ring->data_size + entry->ring->desc_size;
-        skb = dev_alloc_skb(frame_size + NET_IP_ALIGN);
+        skb = dev_alloc_skb(frame_size + 2);
         if (!skb)
                 goto skip_entry;
 
-        skb_reserve(skb, NET_IP_ALIGN);
+        skb_reserve(skb, 2);
         skb_put(skb, frame_size);
 
         /*
-         * Trim the skb_buffer to only contain the valid
-         * frame data (so ignore the device's descriptor).
+         * The data behind the ieee80211 header must be
+         * aligned on a 4 byte boundary.
+         * After that trim the entire buffer down to only
+         * contain the valid frame data excluding the device
+         * descriptor.
          */
+        hdr = (struct ieee80211_hdr *)entry->skb->data;
+        header_size =
+            ieee80211_get_hdrlen(le16_to_cpu(hdr->frame_control));
+
+        if (header_size % 4 == 0) {
+                skb_push(entry->skb, 2);
+                memmove(entry->skb->data, entry->skb->data + 2, skb->len - 2);
+        }
         skb_trim(entry->skb, desc.size);
 
         /*