e1000e: Validate hwtstamp_config completely before applying it

e1000e_hwtstamp_ioctl() should validate all fields of hwtstamp_config
before making any changes.  Currently it copies the configuration to
the e1000_adapter structure before validating it at all.

Change e1000e_config_hwtstamp() to take a pointer to the
hwstamp_config and to copy the config after validating it.

Compile-tested only.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Acked-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/intel/e1000e/netdev.c

@@ -3482,10 +3482,10 @@ s32 e1000e_get_base_timinca(struct e1000_adapter *adapter, u32 *timinca)
  * specified. Matching the kind of event packet is not supported, with the
  * exception of "all V2 events regardless of level 2 or 4".
  **/
-static int e1000e_config_hwtstamp(struct e1000_adapter *adapter)
+static int e1000e_config_hwtstamp(struct e1000_adapter *adapter,
+				  struct hwtstamp_config *config)
 {
 	struct e1000_hw *hw = &adapter->hw;
-	struct hwtstamp_config *config = &adapter->hwtstamp_config;
 	u32 tsync_tx_ctl = E1000_TSYNCTXCTL_ENABLED;
 	u32 tsync_rx_ctl = E1000_TSYNCRXCTL_ENABLED;
 	u32 rxmtrl = 0;
@@ -3586,6 +3586,8 @@ static int e1000e_config_hwtstamp(struct e1000_adapter *adapter)
 		return -ERANGE;
 	}
 
+	adapter->hwtstamp_config = *config;
+
 	/* enable/disable Tx h/w time stamping */
 	regval = er32(TSYNCTXCTL);
 	regval &= ~E1000_TSYNCTXCTL_ENABLED;
@@ -3874,7 +3876,7 @@ void e1000e_reset(struct e1000_adapter *adapter)
 	e1000e_reset_adaptive(hw);
 
 	/* initialize systim and reset the ns time counter */
-	e1000e_config_hwtstamp(adapter);
+	e1000e_config_hwtstamp(adapter, &adapter->hwtstamp_config);
 
 	/* Set EEE advertisement as appropriate */
 	if (adapter->flags2 & FLAG2_HAS_EEE) {
@@ -5797,14 +5799,10 @@ static int e1000e_hwtstamp_ioctl(struct net_device *netdev, struct ifreq *ifr)
 	if (copy_from_user(&config, ifr->ifr_data, sizeof(config)))
 		return -EFAULT;
 
-	adapter->hwtstamp_config = config;
-
-	ret_val = e1000e_config_hwtstamp(adapter);
+	ret_val = e1000e_config_hwtstamp(adapter, &config);
 	if (ret_val)
 		return ret_val;
 
-	config = adapter->hwtstamp_config;
-
 	switch (config.rx_filter) {
 	case HWTSTAMP_FILTER_PTP_V2_L4_SYNC:
 	case HWTSTAMP_FILTER_PTP_V2_L2_SYNC: