rt2x00: Properly reserve room for descriptors in skbs.

Instead of fiddling with the skb->data pointer and thereby risking
out of bounds accesses, properly reserve the space needed in an
skb for descriptors.

Signed-off-by: Gertjan van Wingerde <gwingerde@gmail.com>
Acked-by: Ivo van Doorn <IvDoorn@gmail.com>
Signed-off-by: Ivo van Doorn <IvDoorn@gmail.com>

1 files changed, 8 insertions, 6 deletions

diff --git a/drivers/net/wireless/rt2x00/rt73usb.c b/drivers/net/wireless/rt2x00/rt73usb.c
index bd9a53e5fd9..4ab38c3641c 100644
--- a/drivers/net/wireless/rt2x00/rt73usb.c
+++ b/drivers/net/wireless/rt2x00/rt73usb.c
@@ -1442,7 +1442,7 @@ static void rt73usb_write_tx_desc(struct rt2x00_dev *rt2x00dev,
                                   struct txentry_desc *txdesc)
 {
         struct skb_frame_desc *skbdesc = get_skb_frame_desc(skb);
-        __le32 *txd = (__le32 *)(skb->data - TXD_DESC_SIZE);
+        __le32 *txd = (__le32 *) skb->data;
         u32 word;
 
         /*
@@ -1505,6 +1505,7 @@ static void rt73usb_write_tx_desc(struct rt2x00_dev *rt2x00dev,
         /*
          * Register descriptor details in skb frame descriptor.
          */
+        skbdesc->flags |= SKBDESC_DESC_IN_SKB;
         skbdesc->desc = txd;
         skbdesc->desc_len = TXD_DESC_SIZE;
 }
@@ -1528,6 +1529,12 @@ static void rt73usb_write_beacon(struct queue_entry *entry,
         rt2x00usb_register_write(rt2x00dev, TXRX_CSR9, reg);
 
         /*
+         * Add space for the descriptor in front of the skb.
+         */
+        skb_push(entry->skb, TXD_DESC_SIZE);
+        memset(entry->skb->data, 0, TXD_DESC_SIZE);
+
+        /*
          * Write the TX descriptor for the beacon.
          */
         rt73usb_write_tx_desc(rt2x00dev, entry->skb, txdesc);
@@ -1538,11 +1545,6 @@ static void rt73usb_write_beacon(struct queue_entry *entry,
         rt2x00debug_dump_frame(rt2x00dev, DUMP_FRAME_BEACON, entry->skb);
 
         /*
-         * Take the descriptor in front of the skb into account.
-         */
-        skb_push(entry->skb, TXD_DESC_SIZE);
-
-        /*
          * Write entire beacon with descriptor to register.
          */
         beacon_base = HW_BEACON_OFFSET(entry->entry_idx);