ixgbe: cleanup ixgbe_get_drvinfo to be extra careful with buffer boundaries

Make the code in ixgbe_get_drvinfo more protected against buffer overflow
boundaries by using snprintf and sizeof with snprintf.
Signed-off-by: Don Skidmore <donald.c.skidmore@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ixgbe/ixgbe_ethtool.c

@@ -820,16 +820,19 @@ static void ixgbe_get_drvinfo(struct net_device *netdev,
 	struct ixgbe_adapter *adapter = netdev_priv(netdev);
 	char firmware_version[32];
 
-	strncpy(drvinfo->driver, ixgbe_driver_name, 32);
-	strncpy(drvinfo->version, ixgbe_driver_version, 32);
-
-	sprintf(firmware_version, "%d.%d-%d",
-	        (adapter->eeprom_version & 0xF000) >> 12,
-	        (adapter->eeprom_version & 0x0FF0) >> 4,
-	        adapter->eeprom_version & 0x000F);
-
-	strncpy(drvinfo->fw_version, firmware_version, 32);
-	strncpy(drvinfo->bus_info, pci_name(adapter->pdev), 32);
+	strncpy(drvinfo->driver, ixgbe_driver_name, sizeof(drvinfo->driver));
+	strncpy(drvinfo->version, ixgbe_driver_version,
+	        sizeof(drvinfo->version));
+
+	snprintf(firmware_version, sizeof(firmware_version), "%d.%d-%d",
+	         (adapter->eeprom_version & 0xF000) >> 12,
+	         (adapter->eeprom_version & 0x0FF0) >> 4,
+	         adapter->eeprom_version & 0x000F);
+
+	strncpy(drvinfo->fw_version, firmware_version,
+	        sizeof(drvinfo->fw_version));
+	strncpy(drvinfo->bus_info, pci_name(adapter->pdev),
+	        sizeof(drvinfo->bus_info));
 	drvinfo->n_stats = IXGBE_STATS_LEN;
 	drvinfo->testinfo_len = IXGBE_TEST_LEN;
 	drvinfo->regdump_len = ixgbe_get_regs_len(netdev);