e100, e1000, ixgb: Fix an impossible memory overwrite bug

We keep getting requests from people that think that this might be
an exploitable hole where we would overwrite 4 bytes in the netdev
struct if the pci name would exceed 15 characters. In reality this
will never happen but we fix it anyway.
Signed-off-by: Auke Kok <auke-jan.h.kok@intel.com>

drivers/net/e100.c

@@ -2572,7 +2572,7 @@ static int __devinit e100_probe(struct pci_dev *pdev,
 #ifdef CONFIG_NET_POLL_CONTROLLER
 	netdev->poll_controller = e100_netpoll;
 #endif
-	strcpy(netdev->name, pci_name(pdev));
+	strncpy(netdev->name, pci_name(pdev), sizeof(netdev->name) - 1);
 
 	nic = netdev_priv(netdev);
 	nic->netdev = netdev;

drivers/net/e1000/e1000_main.c

@@ -759,7 +759,7 @@ e1000_probe(struct pci_dev *pdev,
 #ifdef CONFIG_NET_POLL_CONTROLLER
 	netdev->poll_controller = e1000_netpoll;
 #endif
-	strcpy(netdev->name, pci_name(pdev));
+	strncpy(netdev->name, pci_name(pdev), sizeof(netdev->name) - 1);
 
 	netdev->mem_start = mmio_start;
 	netdev->mem_end = mmio_start + mmio_len;

drivers/net/ixgb/ixgb_main.c

@@ -437,7 +437,7 @@ ixgb_probe(struct pci_dev *pdev,
 	netdev->poll_controller = ixgb_netpoll;
 #endif
 
-	strcpy(netdev->name, pci_name(pdev));
+	strncpy(netdev->name, pci_name(pdev), sizeof(netdev->name) - 1);
 	netdev->mem_start = mmio_start;
 	netdev->mem_end = mmio_start + mmio_len;
 	netdev->base_addr = adapter->hw.io_base;