net: fddi: fix a possible null-ptr-deref

bp->SharedMemAddr is set to NULL while bp->SharedMemSize lesser-or-equal 0,
then memset will trigger null-ptr-deref.

fix it by replacing pci_alloc_consistent with dma_zalloc_coherent.
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/fddi/skfp/skfddi.c

@@ -297,10 +297,10 @@ static int skfp_init_one(struct pci_dev *pdev,
 	return 0;
 err_out5:
 	if (smc->os.SharedMemAddr) 
-		pci_free_consistent(pdev, smc->os.SharedMemSize,
+		dma_free_coherent(&pdev->dev, smc->os.SharedMemSize,
 				  smc->os.SharedMemAddr,
 				  smc->os.SharedMemDMA);
-	pci_free_consistent(pdev, MAX_FRAME_SIZE,
+	dma_free_coherent(&pdev->dev, MAX_FRAME_SIZE,
 			  smc->os.LocalRxBuffer, smc->os.LocalRxBufferDMA);
 err_out4:
 	free_netdev(dev);
@@ -328,14 +328,14 @@ static void skfp_remove_one(struct pci_dev *pdev)
 	unregister_netdev(p);
 
 	if (lp->os.SharedMemAddr) {
-		pci_free_consistent(&lp->os.pdev,
+		dma_free_coherent(&pdev->dev,
 				  lp->os.SharedMemSize,
 				  lp->os.SharedMemAddr,
 				  lp->os.SharedMemDMA);
 		lp->os.SharedMemAddr = NULL;
 	}
 	if (lp->os.LocalRxBuffer) {
-		pci_free_consistent(&lp->os.pdev,
+		dma_free_coherent(&pdev->dev,
 				  MAX_FRAME_SIZE,
 				  lp->os.LocalRxBuffer,
 				  lp->os.LocalRxBufferDMA);
@@ -394,7 +394,9 @@ static  int skfp_driver_init(struct net_device *dev)
 	spin_lock_init(&bp->DriverLock);
 	
 	// Allocate invalid frame
-	bp->LocalRxBuffer = pci_alloc_consistent(&bp->pdev, MAX_FRAME_SIZE, &bp->LocalRxBufferDMA);
+	bp->LocalRxBuffer = dma_alloc_coherent(&bp->pdev.dev, MAX_FRAME_SIZE,
+					       &bp->LocalRxBufferDMA,
+					       GFP_ATOMIC);
 	if (!bp->LocalRxBuffer) {
 		printk("could not allocate mem for ");
 		printk("LocalRxBuffer: %d byte\n", MAX_FRAME_SIZE);
@@ -407,23 +409,22 @@ static  int skfp_driver_init(struct net_device *dev)
 	if (bp->SharedMemSize > 0) {
 		bp->SharedMemSize += 16;	// for descriptor alignment
 
-		bp->SharedMemAddr = pci_alloc_consistent(&bp->pdev,
+		bp->SharedMemAddr = dma_zalloc_coherent(&bp->pdev.dev,
 							bp->SharedMemSize,
-							 &bp->SharedMemDMA);
+							&bp->SharedMemDMA,
+							GFP_ATOMIC);
 		if (!bp->SharedMemAddr) {
 			printk("could not allocate mem for ");
 			printk("hardware module: %ld byte\n",
 			       bp->SharedMemSize);
 			goto fail;
 		}
-		bp->SharedMemHeap = 0;	// Nothing used yet.
 
 	} else {
 		bp->SharedMemAddr = NULL;
-		bp->SharedMemHeap = 0;
-	}			// SharedMemSize > 0
+	}
 
-	memset(bp->SharedMemAddr, 0, bp->SharedMemSize);
+	bp->SharedMemHeap = 0;
 
 	card_stop(smc);		// Reset adapter.
 
@@ -442,14 +443,14 @@ static  int skfp_driver_init(struct net_device *dev)
 
 fail:
 	if (bp->SharedMemAddr) {
-		pci_free_consistent(&bp->pdev,
+		dma_free_coherent(&bp->pdev.dev,
 				  bp->SharedMemSize,
 				  bp->SharedMemAddr,
 				  bp->SharedMemDMA);
 		bp->SharedMemAddr = NULL;
 	}
 	if (bp->LocalRxBuffer) {
-		pci_free_consistent(&bp->pdev, MAX_FRAME_SIZE,
+		dma_free_coherent(&bp->pdev.dev, MAX_FRAME_SIZE,
 				  bp->LocalRxBuffer, bp->LocalRxBufferDMA);
 		bp->LocalRxBuffer = NULL;
 	}