From: Paolo Galtieri <[EMAIL PROTECTED]>

Fix the dma_map/dma_unmap relationships and a NULL pointer dereference.
If you do a dma_map_single you must do dma_unmap_single and if you do
a dma_map_page you must do a dma_unmap_page.  The NULL pointer
dereference was caused because the buf_ptr and byte_cnt fields of the
pkt_info structure were not filled in by eth_tx_return_desc().

Signed-off-by: Paolo Galtieri <[EMAIL PROTECTED]>
Signed-off-by: Dale Farnsworth <[EMAIL PROTECTED]>

Index: linux-2.6-mv643xx_enet/drivers/net/mv643xx_eth.c
===================================================================
--- linux-2.6-mv643xx_enet.orig/drivers/net/mv643xx_eth.c
+++ linux-2.6-mv643xx_enet/drivers/net/mv643xx_eth.c
@@ -351,27 +351,19 @@ static int mv643xx_eth_free_tx_queue(str
                        stats->tx_errors++;
                }
 
-               /*
-                * If return_info is different than 0, release the skb.
-                * The case where return_info is not 0 is only in case
-                * when transmitted a scatter/gather packet, where only
-                * last skb releases the whole chain.
-                */
-               if (pkt_info.return_info) {
-                       if (skb_shinfo(pkt_info.return_info)->nr_frags)
-                               dma_unmap_page(NULL, pkt_info.buf_ptr,
-                                               pkt_info.byte_cnt,
-                                               DMA_TO_DEVICE);
-                       else
-                               dma_unmap_single(NULL, pkt_info.buf_ptr,
-                                               pkt_info.byte_cnt,
-                                               DMA_TO_DEVICE);
+               if (pkt_info.cmd_sts & ETH_TX_FIRST_DESC)
+                       dma_unmap_single(NULL, pkt_info.buf_ptr,
+                                       pkt_info.byte_cnt,
+                                       DMA_TO_DEVICE);
+               else
+                       dma_unmap_page(NULL, pkt_info.buf_ptr,
+                                       pkt_info.byte_cnt,
+                                       DMA_TO_DEVICE);
 
+               if (pkt_info.return_info) {
                        dev_kfree_skb_irq(pkt_info.return_info);
                        released = 0;
-               } else
-                       dma_unmap_page(NULL, pkt_info.buf_ptr,
-                                       pkt_info.byte_cnt, DMA_TO_DEVICE);
+               }
        }
 
        spin_unlock(&mp->lock);
@@ -1022,20 +1014,17 @@ static void mv643xx_tx(struct net_device
        struct pkt_info pkt_info;
 
        while (eth_tx_return_desc(mp, &pkt_info) == ETH_OK) {
-               if (pkt_info.return_info) {
-                       if (skb_shinfo(pkt_info.return_info)->nr_frags)
-                               dma_unmap_page(NULL, pkt_info.buf_ptr,
-                                               pkt_info.byte_cnt,
-                                               DMA_TO_DEVICE);
-                       else
-                               dma_unmap_single(NULL, pkt_info.buf_ptr,
-                                               pkt_info.byte_cnt,
-                                               DMA_TO_DEVICE);
+               if (pkt_info.cmd_sts & ETH_TX_FIRST_DESC)
+                       dma_unmap_single(NULL, pkt_info.buf_ptr,
+                                       pkt_info.byte_cnt,
+                                       DMA_TO_DEVICE);
+               else
+                       dma_unmap_page(NULL, pkt_info.buf_ptr,
+                                       pkt_info.byte_cnt,
+                                       DMA_TO_DEVICE);
 
+               if (pkt_info.return_info)
                        dev_kfree_skb_irq(pkt_info.return_info);
-               } else
-                       dma_unmap_page(NULL, pkt_info.buf_ptr,
-                                       pkt_info.byte_cnt, DMA_TO_DEVICE);
        }
 
        if (netif_queue_stopped(dev) &&
@@ -2669,6 +2658,8 @@ static ETH_FUNC_RET_STATUS eth_tx_return
        /* Pass the packet information to the caller */
        p_pkt_info->cmd_sts = command_status;
        p_pkt_info->return_info = mp->tx_skb[tx_desc_used];
+       p_pkt_info->buf_ptr = p_tx_desc_used->buf_ptr;
+       p_pkt_info->byte_cnt = p_tx_desc_used->byte_cnt;
        mp->tx_skb[tx_desc_used] = NULL;
 
        /* Update the next descriptor to release. */
-
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