[PATCH 3.16 018/233] staging: rtl8192e: rtl92e_fill_tx_desc fix write to mapped out memory.

[Ben Hutchings]

3.16.48-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Malcolm Priestley <tvbox...@gmail.com>

commit baabd567f87be05330faa5140f72a91960e7405a upstream.

The driver attempts to alter memory that is mapped to PCI device.

This is because tx_fwinfo_8190pci points to skb->data

Move the pci_map_single to when completed buffer is ready to be mapped with
psdec is empty to drop on mapping error.

Signed-off-by: Malcolm Priestley <tvbox...@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <b...@decadent.org.uk>
---
 drivers/staging/rtl8192e/rtl8192e/r8192E_dev.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

--- a/drivers/staging/rtl8192e/rtl8192e/r8192E_dev.c
+++ b/drivers/staging/rtl8192e/rtl8192e/r8192E_dev.c
@@ -1172,8 +1172,7 @@ void  rtl8192_tx_fill_desc(struct net_de
                           struct cb_desc *cb_desc, struct sk_buff *skb)
 {
        struct r8192_priv *priv = rtllib_priv(dev);
-       dma_addr_t mapping = pci_map_single(priv->pdev, skb->data, skb->len,
-                        PCI_DMA_TODEVICE);
+       dma_addr_t mapping;
        struct tx_fwinfo_8190pci *pTxFwInfo = NULL;
        pTxFwInfo = (struct tx_fwinfo_8190pci *)skb->data;
        memset(pTxFwInfo, 0, sizeof(struct tx_fwinfo_8190pci));
@@ -1184,8 +1183,6 @@ void  rtl8192_tx_fill_desc(struct net_de
                                                pTxFwInfo->TxRate,
                                                cb_desc);
 
-       if (pci_dma_mapping_error(priv->pdev, mapping))
-               RT_TRACE(COMP_ERR, "DMA Mapping error\n");
        if (cb_desc->bAMPDUEnable) {
                pTxFwInfo->AllowAggregation = 1;
                pTxFwInfo->RxMF = cb_desc->ampdu_factor;
@@ -1220,6 +1217,14 @@ void  rtl8192_tx_fill_desc(struct net_de
        }
 
        memset((u8 *)pdesc, 0, 12);
+
+       mapping = pci_map_single(priv->pdev, skb->data, skb->len,
+                                PCI_DMA_TODEVICE);
+       if (pci_dma_mapping_error(priv->pdev, mapping)) {
+               RT_TRACE(COMP_ERR, "DMA Mapping error\n");
+               return;
+       }
+
        pdesc->LINIP = 0;
        pdesc->CmdInit = 1;
        pdesc->Offset = sizeof(struct tx_fwinfo_8190pci) + 8;